Poliomielitis atau polio, adalah penyakit paralisis atau lumpuh yang disebabkan oleh virus. Agen pembawa penyakit ini, sebuah virus yang dinamakan poliovirus (PV), masuk ke tubuh melalui mulut, mengifeksi saluran usus. Virus ini dapat memasuki aliran darah dan mengalir ke sistem saraf pusat menyebabkan melemahnya otot dan kadang kelumpuhan (paralisis).

Daftar isi

 [sembunyikan] 

1 Etimologi 2 Sejarah 3 Virus polio 4 Jenis Polio

o 4.1 Polio non-paralisis o 4.2 Polio paralisis spinal o 4.3 Polio bulbar

5 Anak-anak dan polio 6 Vaksin efektif pertama 7 Usaha pemberantasan polio 8 Pranala luar

[sunting] Etimologi

Kata polio berasal dari [bahasa Yunani] atau bentuknya yang lebih mutakhir, dari "abu-abu" dan "bercak".

[sunting] Sejarah

Polio sudah dikenal sejak zaman pra-sejarah. Lukisan dinding di kuil-kuil Mesir kuno menggambarkan orang-orang sehat dengan kaki layu yang berjalan dengan tongkat. Kaisar Romawi Claudius terserang polio ketika masih kanak-kanak dan menjadi pincang seumur hidupnya.

Virus polio menyerang tanpa peringatan, merusak sistem saraf menimbulkan kelumpuhan permanen, biasanya pada kaki. Sejumlah besar penderita meninggal karena tidak dapat menggerakkan otot pernapasan. Ketika polio menyerang Amerika selama dasawarsa seusai Perang Dunia II, penyakit itu disebut ‘momok semua orang tua’, karena menjangkiti anak-anak terutama yang berumur di bawah lima tahun. Di sana para orang tua tidak membiarkan anak mereka keluar rumah, gedung-gedung bioskop dikunci, kolam renang, sekolah dan bahkan gereja tutup.

[sunting] Virus polio

Poliovirus adalah virus RNA kecil yang terdiri atas tiga strain berbeda dan amat menular. Virus akan menyerang sistem saraf dan kelumpuhan dapat terjadi dalam hitungan jam. Polio menyerang tanpa mengenal usia, lima puluh persen kasus terjadi pada anak berusia antara 3 hingga 5 tahun. Masa inkubasi polio dari gejala pertama berkisar dari 3 hingga 35 hari.

Polio adalah penyakit menular yang dikategorikan sebagai penyakit peradaban. Polio menular melalui kontak antarmanusia. Polio dapat menyebar luas diam-diam karena sebagian besar penderita yang terinfeksi poliovirus tidak memiliki gejala sehingga tidak tahu kalau mereka sendiri sedang terjangkit. Virus masuk ke dalam tubuh melalui mulut ketika seseorang memakan makanan atau minuman yang terkontaminasi feses. Setelah seseorang terkena infeksi, virus akan keluar melalui feses selama beberapa minggu dan saat itulah dapat terjadi penularan virus.

[sunting] Jenis Polio

[sunting] Polio non-paralisis

Polio non-paralisis menyebabkan demam, muntah, sakit perut, lesu, dan sensitif. Terjadi kram otot pada leher dan punggung, otot terasa lembek jika disentuh.

[sunting] Polio paralisis spinal

Strain poliovirus ini menyerang saraf tulang belakang, menghancurkan sel tanduk anterior yang mengontrol pergerakan pada batang tubuh dan otot tungkai. Meskipun strain ini dapat menyebabkan kelumpuhan permanen, kurang dari satu penderita dari 200 penderita akan mengalami kelumpuhan. Kelumpuhan paling sering ditemukan terjadi pada kaki. Setelah virus polio menyerang usus, virus ini akan diserap oleh pembulu darah kapiler pada dinding usus dan diangkut seluruh tubuh. Virus Polio menyerang saraf tulang belakang dan syaraf motorik -- yang mengontrol gerakan fisik. Pada periode inilah muncul gejala seperti flu. Namun, pada penderita yang tidak memiliki kekebalan atau belum divaksinasi, virus ini biasanya akan menyerang seluruh bagian batang saraf tulang belakang dan batang otak. Infeksi ini akan memengaruhi sistem saraf pusat -- menyebar sepanjang serabut saraf. Seiring dengan berkembang biaknya virus dalam sistem saraf pusat, virus akan menghancurkan syaraf motorik. Syaraf motorik tidak memiliki kemampuan regenerasi dan otot yang berhubungan dengannya tidak akan bereaksi terhadap perintah dari sistem saraf pusat. Kelumpuhan pada kaki menyebabkan tungkai menjadi lemas -- kondisi ini disebut acute flaccid paralysis (AFP). Infeksi parah pada sistem saraf pusat dapat menyebabkan kelumpuhan pada batang tubuh dan otot pada toraks (dada) dan abdomen (perut), disebut quadriplegia.

[sunting] Polio bulbar

Polio jenis ini disebabkan oleh tidak adanya kekebalan alami sehingga batang otak ikut terserang. Batang otak mengandung syaraf motorik yang mengatur pernapasan dan saraf kranial, yang mengirim sinyal ke berbagai syaraf yang mengontrol pergerakan bola mata; saraf trigeminal dan saraf muka yang berhubungan dengan pipi, kelenjar air mata, gusi, dan otot muka; saraf auditori yang mengatur pendengaran; saraf glossofaringeal yang membantu proses menelan

dan berbagai fungsi di kerongkongan; pergerakan lidah dan rasa; dan saraf yang mengirim sinyal ke jantung, usus, paru-paru, dan saraf tambahan yang mengatur pergerakan leher.

Tanpa alat bantu pernapasan, polio bulbar dapat menyebabkan kematian. Lima hingga sepuluh persen penderita yang menderita polio bulbar akan meninggal ketika otot pernapasan mereka tidak dapat bekerja. Kematian biasanya terjadi setelah terjadi kerusakan pada saraf kranial yang bertugas mengirim 'perintah bernapas' ke paru-paru. Penderita juga dapat meninggal karena kerusakan pada fungsi penelanan; korban dapat 'tenggelam' dalam sekresinya sendiri kecuali dilakukan penyedotan atau diberi perlakuan trakeostomi untuk menyedot cairan yang disekresikan sebelum masuk ke dalam paru-paru. Namun trakesotomi juga sulit dilakukan apabila penderita telah menggunakan 'paru-paru besi' (iron lung). Alat ini membantu paru-paru yang lemah dengan cara menambah dan mengurangi tekanan udara di dalam tabung. Kalau tekanan udara ditambah, paru-paru akan mengempis, kalau tekanan udara dikurangi, paru-paru akan mengembang. Dengan demikian udara terpompa keluar masuk paru-paru. Infeksi yang jauh lebih parah pada otak dapat menyebabkan koma dan kematian.

Tingkat kematian karena polio bulbar berkisar 25-75% tergantung usia penderita. Hingga saat ini, mereka yang bertahan hidup dari polio jenis ini harus hidup dengan paru-paru besi atau alat bantu pernapasan. Polio bulbar dan spinal sering menyerang bersamaan dan merupakan sub kelas dari polio paralisis. Polio paralisis tidak bersifat permanen. Penderita yang sembuh dapat memiliki fungsi tubuh yang mendekati normal.

[sunting] Anak-anak dan polio

Anak-anak kecil yang terkena polio seringkali hanya mengalami gejala ringan dan menjadi kebal terhadap polio. Karenanya, penduduk di daerah yang memiliki sanitasi baik justru menjadi lebih rentan terhadap polio karena tidak menderita polio ketika masih kecil. Vaksinasi pada saat balita akan sangat membantu pencegahan polio pada masa depan karena polio menjadi lebih berbahaya jika diderita oleh orang dewasa. Orang yang telah menderita polio bukan tidak mungkin akan mengalami gejala tambahan pada masa depan seperti layu otot; gejala ini disebut sindrom post-polio.

[sunting] Vaksin efektif pertama

Vaksin efektif pertama dikembangkan oleh Jonas Salk. Salk menolak untuk mematenkan vaksin ini karena menurutnya vaksin ini milik semua orang seperti halnya sinar matahari. Namun vaksin yang digunakan untuk inokulasi masal adalah vaksin yang dikembangkan oleh Albert Sabin. Inokulasi pencegahan polio anak untuk pertama kalinya diselenggarakan di Pittsburgh, Pennsylvania pada 23 Februari 1954. Polio hilang di Amerika pada tahun 1979.

[sunting] Usaha pemberantasan polio

Pada tahun 1938, Presiden Roosevelt mendirikan Yayasan Nasional Bagi Kelumpuhan Anak-Anak, yang bertujuan menemukan pencegah polio, dan merawat mereka yang sudah terjangkit. Yayasan itu membentuk March of Dimes. Ibu-ibu melakukan kunjungan dari rumah ke rumah,

anak-anak membantu melakukan sesuatu untuk orang lain, bioskop memasang iklan, semuanya bertujuan minta bantuan satu dime, atau sepuluh sen. Dana yang masuk waktu itu digunakan untuk membiayai penelitian Dokter Jonas Salk yang menghasilkan vaksin efektif pertama. Tahun 1952, di Amerika terdapat 58 ribu kasus polio. Tahun 1955 vaksin Salk mulai digunakan. Tahun 1963, setelah puluhan juta anak divaksin, di Amerika hanya ada 396 kasus polio.

Pada tahun 1955, Presiden Dwight Eisenhower mengumumkan bahwa Amerika akan mengajarkan kepada negara-negara lain cara membuat vaksin polio. Informasi ini diberikan secara gratis, kepada 75 negara, termasuk Uni Soviet.

Tahun 1988, Organisasi Kesehatan Dunia atau WHO mensahkan resolusi untuk menghapus polio sebelum tahun 2000. Pada saat itu masih terdapat sekitar 350 ribu kasus polio di seluruh dunia. Meskipun pada tahun 2000, polio belum terbasmi, tetapi jumlah kasusnya telah berkurang hingga di bawah 500. Polio tidak ada lagi di Asia Timur, Amerika Latin, Timur Tengah atau Eropa, tetapi masih terdapat di Nigeria, dan sejumlah kecil di India dan Pakistan. India telah melakukan usaha pemberantasan polio yang cukup sukses. Sedangkan di Nigeria, penyakit ini masih terus berjangkit karena pemerintah yang berkuasa mencurigai vaksin polio yang diberikan dapat mengurangi fertilitas dan menyebarkan HIV. Tahun 2004, pemerintah Nigeria meminta WHO untuk melakukan vaksinasi lagi setelah penyakit polio kembali menyebar ke seluruh Nigeria dan 10 negara tetangganya. Konflik internal dan perang saudara di Sudan dan Pantai Gading juga mempersulit pemberian vaksin polio.

Meskipun banyak usaha telah dilakukan, pada tahun 2004 angka infeksi polio meningkat menjadi 1.185 di 17 negara dari 784 di 15 negara pada tahun 2003. Sebagian penderita berada di Asia dan 1.037 ada di Afrika. Nigeria memiliki 763 penderita, India 129, dan Sudan 112.

Pada 5 Mei 2005, dilaporkan terjadi ledakan infeksi polio di Sukabumi akibat strain virus yang menyebabkan wabah di Nigeria. Virus ini diperkirakan terbawa dari Nigeria ke Arab dan sampai ke Indonesia melalui tenaga kerja Indonesia yang bekerja di Arab atau orang yang bepergian ke Arab untuk haji atau hal lainnya.

[sunting] Pranala luar

(Indonesia) Infografis TEMPO tentang polio (bagian 1) (Indonesia) Infografis TEMPO tentang polio (bagian 2)

Etimologi

Kata polio berasal dari [bahasa Yunani] atau bentuknya yang lebih mutakhir, dari "abu-abu" dan "bercak".

[sunting] Sejarah

Polio sudah dikenal sejak zaman pra-sejarah. Lukisan dinding di kuil-kuil Mesir kuno menggambarkan orang-orang sehat dengan kaki layu yang berjalan dengan tongkat. Kaisar

Romawi Claudius terserang polio ketika masih kanak-kanak dan menjadi pincang seumur hidupnya.

Virus polio menyerang tanpa peringatan, merusak sistem saraf menimbulkan kelumpuhan permanen, biasanya pada kaki. Sejumlah besar penderita meninggal karena tidak dapat menggerakkan otot pernapasan. Ketika polio menyerang Amerika selama dasawarsa seusai Perang Dunia II, penyakit itu disebut ‘momok semua orang tua’, karena menjangkiti anak-anak terutama yang berumur di bawah lima tahun. Di sana para orang tua tidak membiarkan anak mereka keluar rumah, gedung-gedung bioskop dikunci, kolam renang, sekolah dan bahkan gereja tutup.

[sunting] Virus polio

Poliovirus adalah virus RNA kecil yang terdiri atas tiga strain berbeda dan amat menular. Virus akan menyerang sistem saraf dan kelumpuhan dapat terjadi dalam hitungan jam. Polio menyerang tanpa mengenal usia, lima puluh persen kasus terjadi pada anak berusia antara 3 hingga 5 tahun. Masa inkubasi polio dari gejala pertama berkisar dari 3 hingga 35 hari.

Polio adalah penyakit menular yang dikategorikan sebagai penyakit peradaban. Polio menular melalui kontak antarmanusia. Polio dapat menyebar luas diam-diam karena sebagian besar penderita yang terinfeksi poliovirus tidak memiliki gejala sehingga tidak tahu kalau mereka sendiri sedang terjangkit. Virus masuk ke dalam tubuh melalui mulut ketika seseorang memakan makanan atau minuman yang terkontaminasi feses. Setelah seseorang terkena infeksi, virus akan keluar melalui feses selama beberapa minggu dan saat itulah dapat terjadi penularan virus.

[sunting] Jenis Polio

[sunting] Polio non-paralisis

Polio non-paralisis menyebabkan demam, muntah, sakit perut, lesu, dan sensitif. Terjadi kram otot pada leher dan punggung, otot terasa lembek jika disentuh.

[sunting] Polio paralisis spinal

Strain poliovirus ini menyerang saraf tulang belakang, menghancurkan sel tanduk anterior yang mengontrol pergerakan pada batang tubuh dan otot tungkai. Meskipun strain ini dapat menyebabkan kelumpuhan permanen, kurang dari satu penderita dari 200 penderita akan mengalami kelumpuhan. Kelumpuhan paling sering ditemukan terjadi pada kaki. Setelah virus polio menyerang usus, virus ini akan diserap oleh pembulu darah kapiler pada dinding usus dan diangkut seluruh tubuh. Virus Polio menyerang saraf tulang belakang dan syaraf motorik -- yang mengontrol gerakan fisik. Pada periode inilah muncul gejala seperti flu. Namun, pada penderita yang tidak memiliki kekebalan atau belum divaksinasi, virus ini biasanya akan menyerang seluruh bagian batang saraf tulang belakang dan batang otak. Infeksi ini akan memengaruhi sistem saraf pusat -- menyebar sepanjang serabut saraf. Seiring dengan berkembang biaknya virus dalam sistem saraf pusat, virus akan menghancurkan syaraf motorik. Syaraf motorik tidak

memiliki kemampuan regenerasi dan otot yang berhubungan dengannya tidak akan bereaksi terhadap perintah dari sistem saraf pusat. Kelumpuhan pada kaki menyebabkan tungkai menjadi lemas -- kondisi ini disebut acute flaccid paralysis (AFP). Infeksi parah pada sistem saraf pusat dapat menyebabkan kelumpuhan pada batang tubuh dan otot pada toraks (dada) dan abdomen (perut), disebut quadriplegia.

[sunting] Polio bulbar

Polio jenis ini disebabkan oleh tidak adanya kekebalan alami sehingga batang otak ikut terserang. Batang otak mengandung syaraf motorik yang mengatur pernapasan dan saraf kranial, yang mengirim sinyal ke berbagai syaraf yang mengontrol pergerakan bola mata; saraf trigeminal dan saraf muka yang berhubungan dengan pipi, kelenjar air mata, gusi, dan otot muka; saraf auditori yang mengatur pendengaran; saraf glossofaringeal yang membantu proses menelan dan berbagai fungsi di kerongkongan; pergerakan lidah dan rasa; dan saraf yang mengirim sinyal ke jantung, usus, paru-paru, dan saraf tambahan yang mengatur pergerakan leher.

Tanpa alat bantu pernapasan, polio bulbar dapat menyebabkan kematian. Lima hingga sepuluh persen penderita yang menderita polio bulbar akan meninggal ketika otot pernapasan mereka tidak dapat bekerja. Kematian biasanya terjadi setelah terjadi kerusakan pada saraf kranial yang bertugas mengirim 'perintah bernapas' ke paru-paru. Penderita juga dapat meninggal karena kerusakan pada fungsi penelanan; korban dapat 'tenggelam' dalam sekresinya sendiri kecuali dilakukan penyedotan atau diberi perlakuan trakeostomi untuk menyedot cairan yang disekresikan sebelum masuk ke dalam paru-paru. Namun trakesotomi juga sulit dilakukan apabila penderita telah menggunakan 'paru-paru besi' (iron lung). Alat ini membantu paru-paru yang lemah dengan cara menambah dan mengurangi tekanan udara di dalam tabung. Kalau tekanan udara ditambah, paru-paru akan mengempis, kalau tekanan udara dikurangi, paru-paru akan mengembang. Dengan demikian udara terpompa keluar masuk paru-paru. Infeksi yang jauh lebih parah pada otak dapat menyebabkan koma dan kematian.

Tingkat kematian karena polio bulbar berkisar 25-75% tergantung usia penderita. Hingga saat ini, mereka yang bertahan hidup dari polio jenis ini harus hidup dengan paru-paru besi atau alat bantu pernapasan. Polio bulbar dan spinal sering menyerang bersamaan dan merupakan sub kelas dari polio paralisis. Polio paralisis tidak bersifat permanen. Penderita yang sembuh dapat memiliki fungsi tubuh yang mendekati normal.

[sunting] Anak-anak dan polio

Anak-anak kecil yang terkena polio seringkali hanya mengalami gejala ringan dan menjadi kebal terhadap polio. Karenanya, penduduk di daerah yang memiliki sanitasi baik justru menjadi lebih rentan terhadap polio karena tidak menderita polio ketika masih kecil. Vaksinasi pada saat balita akan sangat membantu pencegahan polio pada masa depan karena polio menjadi lebih berbahaya jika diderita oleh orang dewasa. Orang yang telah menderita polio bukan tidak mungkin akan mengalami gejala tambahan pada masa depan seperti layu otot; gejala ini disebut sindrom post-polio.

[sunting] Vaksin efektif pertama

Vaksin efektif pertama dikembangkan oleh Jonas Salk. Salk menolak untuk mematenkan vaksin ini karena menurutnya vaksin ini milik semua orang seperti halnya sinar matahari. Namun vaksin yang digunakan untuk inokulasi masal adalah vaksin yang dikembangkan oleh Albert Sabin. Inokulasi pencegahan polio anak untuk pertama kalinya diselenggarakan di Pittsburgh, Pennsylvania pada 23 Februari 1954. Polio hilang di Amerika pada tahun 1979.

[sunting] Usaha pemberantasan polio

Pada tahun 1938, Presiden Roosevelt mendirikan Yayasan Nasional Bagi Kelumpuhan Anak-Anak, yang bertujuan menemukan pencegah polio, dan merawat mereka yang sudah terjangkit. Yayasan itu membentuk March of Dimes. Ibu-ibu melakukan kunjungan dari rumah ke rumah, anak-anak membantu melakukan sesuatu untuk orang lain, bioskop memasang iklan, semuanya bertujuan minta bantuan satu dime, atau sepuluh sen. Dana yang masuk waktu itu digunakan untuk membiayai penelitian Dokter Jonas Salk yang menghasilkan vaksin efektif pertama. Tahun 1952, di Amerika terdapat 58 ribu kasus polio. Tahun 1955 vaksin Salk mulai digunakan. Tahun 1963, setelah puluhan juta anak divaksin, di Amerika hanya ada 396 kasus polio.

Pada tahun 1955, Presiden Dwight Eisenhower mengumumkan bahwa Amerika akan mengajarkan kepada negara-negara lain cara membuat vaksin polio. Informasi ini diberikan secara gratis, kepada 75 negara, termasuk Uni Soviet.

Tahun 1988, Organisasi Kesehatan Dunia atau WHO mensahkan resolusi untuk menghapus polio sebelum tahun 2000. Pada saat itu masih terdapat sekitar 350 ribu kasus polio di seluruh dunia. Meskipun pada tahun 2000, polio belum terbasmi, tetapi jumlah kasusnya telah berkurang hingga di bawah 500. Polio tidak ada lagi di Asia Timur, Amerika Latin, Timur Tengah atau Eropa, tetapi masih terdapat di Nigeria, dan sejumlah kecil di India dan Pakistan. India telah melakukan usaha pemberantasan polio yang cukup sukses. Sedangkan di Nigeria, penyakit ini masih terus berjangkit karena pemerintah yang berkuasa mencurigai vaksin polio yang diberikan dapat mengurangi fertilitas dan menyebarkan HIV. Tahun 2004, pemerintah Nigeria meminta WHO untuk melakukan vaksinasi lagi setelah penyakit polio kembali menyebar ke seluruh Nigeria dan 10 negara tetangganya. Konflik internal dan perang saudara di Sudan dan Pantai Gading juga mempersulit pemberian vaksin polio.

Meskipun banyak usaha telah dilakukan, pada tahun 2004 angka infeksi polio meningkat menjadi 1.185 di 17 negara dari 784 di 15 negara pada tahun 2003. Sebagian penderita berada di Asia dan 1.037 ada di Afrika. Nigeria memiliki 763 penderita, India 129, dan Sudan 112.

Pada 5 Mei 2005, dilaporkan terjadi ledakan infeksi polio di Sukabumi akibat strain virus yang menyebabkan wabah di Nigeria. Virus ini diperkirakan terbawa dari Nigeria ke Arab dan sampai ke Indonesia melalui tenaga kerja Indonesia yang bekerja di Arab atau orang yang bepergian ke Arab untuk haji atau hal lainnya.

Poliomyelitis From Wikipedia, the free encyclopedia

Jump to: navigation, search

"Polio" redirects here. For the virus, see Poliovirus.

Not to be confused with poliosis, a condition of the hair being or becoming white or grey.

Poliomyelitis

Classification and external resources

A man with an atrophied right leg due to poliomyelitis

ICD-10 A 80 , B 91

ICD-9 045, 138

DiseasesDB 10209

MedlinePlus 001402

eMedicine ped/1843 pmr/6

MeSH C02.182.600.700

Poliomyelitis (pōlee ō mī ə lītiss), often called polio or infantile paralysis, is an acute, viral, infectious disease spread from person to person, primarily via the fecal-oral route.[1] The term derives from the Greek poliós (πολιός), meaning "grey", myelós (µυελός), referring to the "spinal cord", and the suffix -itis, which denotes inflammation.[2]

Although approximately 90% of polio infections cause no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream.[3] In about 1% of cases, the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved. Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs. Bulbar polio leads to weakness of muscles innervated by cranial nerves. Bulbospinal polio is a combination of bulbar and spinal paralysis.[4]

Poliomyelitis was first recognized as a distinct condition by Jakob Heine in 1840.[5] Its causative agent, poliovirus, was identified in 1908 by Karl Landsteiner.[5] Although major polio epidemics were unknown before the late 19th century, polio was one of the most dreaded childhood diseases of the 20th century. Polio epidemics have crippled thousands of people, mostly young children; the disease has caused paralysis and death for much of human history. Polio had existed for thousands of years quietly as an endemic pathogen until the 1880s, when major epidemics began to occur in Europe; soon after, widespread epidemics appeared in the United States.[6]

By 1910, much of the world experienced a dramatic increase in polio cases and epidemics became regular events, primarily in cities during the summer months. These epidemics—which left thousands of children and adults paralyzed—provided the impetus for a "Great Race" towards the development of a vaccine. Developed in the 1950s, polio vaccines are credited with reducing the global number of polio cases per year from many hundreds of thousands to around a thousand.[7] Enhanced vaccination efforts led by the World Health Organization, UNICEF, and Rotary International could result in global eradication of the disease.[8][9]

Contents

[hide]

1 Classification 2 Cause 3 Transmission 4 Pathophysiology

o 4.1 Paralytic polio 5 Diagnosis 6 Prevention

o 6.1 Passive immunization o 6.2 Vaccine

7 Treatment 8 Prognosis

o 8.1 Recovery

o 8.2 Complications o 8.3 Post-polio syndrome

9 Eradication 10 History 11 See also 12 Notes and references 13 Further reading 14 External links

[edit] Classification

Outcomes of poliovirus infection

Outcome Proportion of cases[4]

Asymptomatic 90–95%

Minor illness 4–8%

Nonparalytic asepticmeningitis

1–2%

Paralytic poliomyelitis 0.1–0.5%

— Spinal polio 79% of paralytic cases

— Bulbospinal polio 19% of paralytic cases

— Bulbar polio 2% of paralytic cases

The term "poliomyelitis" is used to identify the disease caused by any of the three serotypes of poliovirus. Two basic patterns of polio infection are described: a minor illness which does not involve the central nervous system (CNS), sometimes called abortive poliomyelitis, and a major illness involving the CNS, which may be paralytic or nonparalytic.[10] In most people with a normal immune system, a poliovirus infection is asymptomatic. Rarely, the infection produces minor symptoms; these may include upper respiratory tract infection (sore throat and fever), gastrointestinal disturbances (nausea, vomiting, abdominal pain, constipation or, rarely, diarrhea), and influenza-like illness.[4]

The virus enters the central nervous system in about 3% of infections. Most patients with CNS involvement develop nonparalytic aseptic meningitis, with symptoms of headache, neck, back, abdominal and extremity pain, fever, vomiting, lethargy and irritability.[2][11] About one to five in 1000 cases progress to paralytic disease, in which the muscles become weak, floppy and poorly controlled, and finally completely paralyzed; this condition is known as acute flaccid paralysis.

[12] Depending on the site of paralysis, paralytic poliomyelitis is classified as spinal, bulbar, or bulbospinal. Encephalitis, an infection of the brain tissue itself, can occur in rare cases, and is usually restricted to infants. It is characterized by confusion, changes in mental status, headaches, fever, and less commonly, seizures and spastic paralysis.[13]

[edit] Cause

Main article: Poliovirus

A TEM micrograph of poliovirus

Poliomyelitis is caused by infection with a member of the genus Enterovirus known as poliovirus (PV). This group of RNA viruses colonize the gastrointestinal tract [1] — specifically the oropharynx and the intestine. The incubation time (to the first signs and symptoms) ranges from three to 35 days, with a more common span of six to 20 days.[4] PV infects and causes disease in humans alone.[3] Its structure is very simple, composed of a single (+) sense RNA genome enclosed in a protein shell called a capsid.[3] In addition to protecting the virus’s genetic material, the capsid proteins enable poliovirus to infect certain types of cells. Three serotypes of poliovirus have been identified—poliovirus type 1 (PV1), type 2 (PV2), and type 3 (PV3)—each with a slightly different capsid protein.[14] All three are extremely virulent and produce the same disease symptoms.[3] PV1 is the most commonly encountered form, and the one most closely associated with paralysis.[15]

Individuals who are exposed to the virus, either through infection or by immunization with polio vaccine, develop immunity. In immune individuals, IgA antibodies against poliovirus are present in the tonsils and gastrointestinal tract, and are able to block virus replication; IgG and IgM antibodies against PV can prevent the spread of the virus to motor neurons of the central nervous

system.[16] Infection or vaccination with one serotype of poliovirus does not provide immunity against the other serotypes, and full immunity requires exposure to each serotype.[16]

A rare condition with a similar presentation, nonpoliovirus poliomyelitis, may result from infections with nonpoliovirus enteroviruses.[17]

[edit] Transmission

Poliomyelitis is highly contagious via the oral-oral (oropharyngeal source) and fecal-oral (intestinal source) routes.[16] In endemic areas, wild polioviruses can infect virtually the entire human population.[18] It is seasonal in temperate climates, with peak transmission occurring in summer and autumn.[16] These seasonal differences are far less pronounced in tropical areas.[18] The time between first exposure and first symptoms, known as the incubation period, is usually six to 20 days, with a maximum range of three to 35 days.[19] Virus particles are excreted in the feces for several weeks following initial infection.[19] The disease is transmitted primarily via the fecal-oral route, by ingesting contaminated food or water. It is occasionally transmitted via the oral-oral route,[15] a mode especially visible in areas with good sanitation and hygiene.[16] Polio is most infectious between seven and 10 days before and after the appearance of symptoms, but transmission is possible as long as the virus remains in the saliva or feces.[15]

Factors that increase the risk of polio infection or affect the severity of the disease include immune deficiency,[20] malnutrition,[21] tonsillectomy,[22] physical activity immediately following the onset of paralysis,[23] skeletal muscle injury due to injection of vaccines or therapeutic agents,[24] and pregnancy.[25] Although the virus can cross the placenta during pregnancy, the fetus does not appear to be affected by either maternal infection or polio vaccination.[26] Maternal antibodies also cross the placenta, providing passive immunity that protects the infant from polio infection during the first few months of life.[27]

As a precaution against infection, public swimming pools were often closed in affected areas during poliomyelitis epidemics.

[edit] Pathophysiology

A blockage of the lumbar anterior spinal cord artery due to polio (PV3)

Poliovirus enters the body through the mouth, infecting the first cells with which it comes in contact—the pharynx and intestinal mucosa. It gains entry by binding to an immunoglobulin-like receptor, known as the poliovirus receptor or CD155, on the cell membrane.[28] The virus then hijacks the host cell's own machinery, and begins to replicate. Poliovirus divides within gastrointestinal cells for about a week, from where it spreads to the tonsils (specifically the follicular dendritic cells residing within the tonsilar germinal centers), the intestinal lymphoid tissue including the M cells of Peyer's patches, and the deep cervical and mesenteric lymph nodes, where it multiplies abundantly. The virus is subsequently absorbed into the bloodstream.[29]

Known as viremia, the presence of virus in the bloodstream enables it to be widely distributed throughout the body. Poliovirus can survive and multiply within the blood and lymphatics for long periods of time, sometimes as long as 17 weeks.[30] In a small percentage of cases, it can spread and replicate in other sites, such as brown fat, the reticuloendothelial tissues, and muscle.[31] This sustained replication causes a major viremia, and leads to the development of minor influenza-like symptoms. Rarely, this may progress and the virus may invade the central nervous system, provoking a local inflammatory response. In most cases, this causes a self-limiting inflammation of the meninges, the layers of tissue surrounding the brain, which is known as nonparalytic aseptic meningitis.[2] Penetration of the CNS provides no known benefit to the virus, and is quite possibly an incidental deviation of a normal gastrointestinal infection.[32] The mechanisms by which poliovirus spreads to the CNS are poorly understood, but it appears to be primarily a chance event—largely independent of the age, gender, or socioeconomic position of the individual.[32]

[edit] Paralytic polio

Denervation of skeletal muscle tissue secondary to poliovirus infection can lead to paralysis.

In around 1% of infections, poliovirus spreads along certain nerve fiber pathways, preferentially replicating in and destroying motor neurons within the spinal cord, brain stem, or motor cortex. This leads to the development of paralytic poliomyelitis, the various forms of which (spinal, bulbar, and bulbospinal) vary only with the amount of neuronal damage and inflammation that occurs, and the region of the CNS affected.

The destruction of neuronal cells produces lesions within the spinal ganglia; these may also occur in the reticular formation, vestibular nuclei, cerebellar vermis, and deep cerebellar nuclei.[32] Inflammation associated with nerve cell destruction often alters the color and appearance of the gray matter in the spinal column, causing it to appear reddish and swollen.[2] Other destructive changes associated with paralytic disease occur in the forebrain region, specifically the hypothalamus and thalamus.[32] The molecular mechanisms by which poliovirus causes paralytic disease are poorly understood.

Early symptoms of paralytic polio include high fever, headache, stiffness in the back and neck, asymmetrical weakness of various muscles, sensitivity to touch, difficulty swallowing, muscle pain, loss of superficial and deep reflexes, paresthesia (pins and needles), irritability, constipation, or difficulty urinating. Paralysis generally develops one to ten days after early symptoms begin, progresses for two to three days, and is usually complete by the time the fever breaks.[33]

The likelihood of developing paralytic polio increases with age, as does the extent of paralysis. In children, nonparalytic meningitis is the most likely consequence of CNS involvement, and paralysis occurs in only one in 1000 cases. In adults, paralysis occurs in one in 75 cases.[34] In children under five years of age, paralysis of one leg is most common; in adults, extensive paralysis of the chest and abdomen also affecting all four limbs—quadriplegia—is more likely.[35] Paralysis rates also vary depending on the serotype of the infecting poliovirus; the highest rates of paralysis (one in 200) are associated with poliovirus type 1, the lowest rates (one in 2,000) are associated with type 2.[36]

[edit] Spinal polio

The location of motor neurons in the anterior horn cells of the spinal column

Spinal polio, the most common form of paralytic poliomyelitis, results from viral invasion of the motor neurons of the anterior horn cells, or the ventral (front) gray matter section in the spinal column, which are responsible for movement of the muscles, including those of the trunk, limbs and the intercostal muscles.[12] Virus invasion causes inflammation of the nerve cells, leading to damage or destruction of motor neuron ganglia. When spinal neurons die, Wallerian degeneration takes place, leading to weakness of those muscles formerly innervated by the now-dead neurons.[37] With the destruction of nerve cells, the muscles no longer receive signals from

the brain or spinal cord; without nerve stimulation, the muscles atrophy, becoming weak, floppy and poorly controlled, and finally completely paralyzed.[12] Progression to maximum paralysis is rapid (two to four days), and is usually associated with fever and muscle pain.[37] Deep tendon reflexes are also affected, and are usually absent or diminished; sensation (the ability to feel) in the paralyzed limbs, however, is not affected.[37]

The extent of spinal paralysis depends on the region of the cord affected, which may be cervical, thoracic, or lumbar.[38] The virus may affect muscles on both sides of the body, but more often the paralysis is asymmetrical.[29] Any limb or combination of limbs may be affected—one leg, one arm, or both legs and both arms. Paralysis is often more severe proximally (where the limb joins the body) than distally (the fingertips and toes).[29]

[edit] Bulbar polio

The location and anatomy of the bulbar region (in orange)

Making up about 2% of cases of paralytic polio, bulbar polio occurs when poliovirus invades and destroys nerves within the bulbar region of the brain stem.[4] The bulbar region is a white matter pathway that connects the cerebral cortex to the brain stem. The destruction of these nerves weakens the muscles supplied by the cranial nerves, producing symptoms of encephalitis, and causes difficulty breathing, speaking and swallowing.[11] Critical nerves affected are the glossopharyngeal nerve, which partially controls swallowing and functions in the throat, tongue movement and taste; the vagus nerve, which sends signals to the heart, intestines, and lungs; and the accessory nerve, which controls upper neck movement. Due to the effect on swallowing, secretions of mucus may build up in the airway, causing suffocation.[33] Other signs and symptoms include facial weakness, caused by destruction of the trigeminal nerve and facial nerve, which innervate the cheeks, tear ducts, gums, and muscles of the face, among other structures; double vision; difficulty in chewing; and abnormal respiratory rate, depth, and rhythm, which may lead to respiratory arrest. Pulmonary edema and shock are also possible, and may be fatal.[38]

[edit] Bulbospinal polio

Approximately 19% of all paralytic polio cases have both bulbar and spinal symptoms; this subtype is called respiratory or bulbospinal polio.[4] Here, the virus affects the upper part of the cervical spinal cord (cervical vertebrae C3 through C5), and paralysis of the diaphragm occurs. The critical nerves affected are the phrenic nerve, which drives the diaphragm to inflate the lungs, and those that drive the muscles needed for swallowing. By destroying these nerves, this form of polio affects breathing, making it difficult or impossible for the patient to breathe without the support of a ventilator. It can lead to paralysis of the arms and legs and may also affect swallowing and heart functions.[39]

[edit] Diagnosis

Paralytic poliomyelitis may be clinically suspected in individuals experiencing acute onset of flaccid paralysis in one or more limbs with decreased or absent tendon reflexes in the affected limbs that cannot be attributed to another apparent cause, and without sensory or cognitive loss.[40]

A laboratory diagnosis is usually made based on recovery of poliovirus from a stool sample or a swab of the pharynx. Antibodies to poliovirus can be diagnostic, and are generally detected in the blood of infected patients early in the course of infection.[4] Analysis of the patient's cerebrospinal fluid (CSF), which is collected by a lumbar puncture ("spinal tap"), reveals an increased number of white blood cells (primarily lymphocytes) and a mildly elevated protein level. Detection of virus in the CSF is diagnostic of paralytic polio, but rarely occurs.[4]

If poliovirus is isolated from a patient experiencing acute flaccid paralysis, it is further tested through oligonucleotide mapping (genetic fingerprinting), or more recently by PCR amplification, to determine whether it is "wild type" (that is, the virus encountered in nature) or "vaccine type" (derived from a strain of poliovirus used to produce polio vaccine).[41] It is important to determine the source of the virus because for each reported case of paralytic polio caused by wild poliovirus, an estimated another 200 to 3,000 contagious asymptomatic carriers exist.[42]

[edit] Prevention

[edit] Passive immunization

In 1950, William Hammon at the University of Pittsburgh purified the gamma globulin component of the blood plasma of polio survivors.[43] Hammon proposed the gamma globulin, which contained antibodies to poliovirus, could be used to halt poliovirus infection, prevent disease, and reduce the severity of disease in other patients who had contracted polio. The results of a large clinical trial were promising; the gamma globulin was shown to be about 80% effective in preventing the development of paralytic poliomyelitis.[44] It was also shown to reduce the severity of the disease in patients who developed polio.[43] The gamma globulin approach was later deemed impractical for widespread use, however, due in large part to the limited supply of

blood plasma, so the medical community turned its focus to the development of a polio vaccine.[45]

[edit] Vaccine

Main article: Polio vaccine

A child receiving an oral polio vaccine

Two types of vaccine are used throughout the world to combat polio. Both types induce immunity to polio, efficiently blocking person-to-person transmission of wild poliovirus, thereby protecting both individual vaccine recipients and the wider community (so-called herd immunity).[46]

The first candidate polio vaccine, based on one serotype of a live but attenuated (weakened) virus, was developed by the virologist Hilary Koprowski. Koprowski's prototype vaccine was given to an eight-year-old boy on February 27, 1950.[47] Koprowski continued to work on the vaccine throughout the 1950s, leading to large-scale trials in the then Belgian Congo and the vaccination of seven million children in Poland against serotypes PV1 and PV3 between 1958 and 1960.[48]

The second inactivated virus vaccine was developed in 1952 by Jonas Salk at the University of Pittsburgh, and announced to the world on April 12, 1955.[49] The Salk vaccine, or inactivated poliovirus vaccine (IPV), is based on poliovirus grown in a type of monkey kidney tissue culture (vero cell line), which is chemically inactivated with formalin.[16] After two doses of IPV (given by injection), 90% or more of individuals develop protective antibody to all three serotypes of poliovirus, and at least 99% are immune to poliovirus following three doses.[4]

Subsequently, Albert Sabin developed another live, oral polio vaccine (OPV). It was produced by the repeated passage of the virus through nonhuman cells at subphysiological temperatures.[50]

The attenuated poliovirus in the Sabin vaccine replicates very efficiently in the gut, the primary

site of wild poliovirus infection and replication, but the vaccine strain is unable to replicate efficiently within nervous system tissue.[51] A single dose of Sabin's oral polio vaccine produces immunity to all three poliovirus serotypes in about 50% of recipients. Three doses of live-attenuated OPV produce protective antibody to all three poliovirus types in more than 95% of recipients.[4] Human trials of Sabin's vaccine began in 1957,[52] and in 1958 it was selected, in competition with the live vaccines of Koprowski and other researchers, by the US National Institutes of Health.[48] Licensed in 1962,[52] it rapidly became the only polio vaccine used worldwide.[48]

Because OPV is inexpensive, easy to administer, and produces excellent immunity in the intestine (which helps prevent infection with wild virus in areas where it is endemic), it has been the vaccine of choice for controlling poliomyelitis in many countries.[53] On very rare occasions (about one case per 750,000 vaccine recipients), the attenuated virus in OPV reverts into a form that can paralyze.[19] Most industrialized countries have switched to IPV, which cannot revert, either as the sole vaccine against poliomyelitis or in combination with oral polio vaccine.[54]

[edit] Treatment

There is no cure for polio. The focus of modern treatment has been on providing relief of symptoms, speeding recovery and preventing complications. Supportive measures include antibiotics to prevent infections in weakened muscles, analgesics for pain, moderate exercise and a nutritious diet.[55] Treatment of polio often requires long-term rehabilitation, including physical therapy, braces, corrective shoes and, in some cases, orthopedic surgery.[38]

Portable ventilators may be required to support breathing. Historically, a noninvasive, negative-pressure ventilator, more commonly called an iron lung, was used to artificially maintain respiration during an acute polio infection until a person could breathe independently (generally about one to two weeks). Today, many polio survivors with permanent respiratory paralysis use modern jacket-type negative-pressure ventilators worn over the chest and abdomen.[56]

Other historical treatments for polio include hydrotherapy, electrotherapy, massage and passive motion exercises, and surgical treatments, such as tendon lengthening and nerve grafting.[12] Devices such as rigid braces and body casts—which tended to cause muscle atrophy due to the limited movement of the user—were also touted as effective treatments.[57]

[edit] Prognosis

Patients with abortive polio infections recover completely. In those who develop only aseptic meningitis, the symptoms can be expected to persist for two to ten days, followed by complete recovery.[58] In cases of spinal polio, if the affected nerve cells are completely destroyed, paralysis will be permanent; cells that are not destroyed, but lose function temporarily, may recover within four to six weeks after onset.[58] Half the patients with spinal polio recover fully; one-quarter recover with mild disability, and the remaining quarter are left with severe disability.[59] The degree of both acute paralysis and residual paralysis is likely to be proportional to the

degree of viremia, and inversely proportional to the degree of immunity.[32] Spinal polio is rarely fatal.[33]

A child with a deformity of her right leg due to polio

Without respiratory support, consequences of poliomyelitis with respiratory involvement include suffocation or pneumonia from aspiration of secretions.[56] Overall, 5–10% of patients with paralytic polio die due to the paralysis of muscles used for breathing. The mortality rate varies by age: 2–5% of children and up to 15–30% of adults die.[4] Bulbar polio often causes death if respiratory support is not provided;[39] with support, its mortality rate ranges from 25 to 75%, depending on the age of the patient.[4][60] When positive pressure ventilators are available, the mortality can be reduced to 15%.[61]

[edit] Recovery

Many cases of poliomyelitis result in only temporary paralysis.[12] Nerve impulses return to the formerly paralyzed muscle within a month, and recovery is usually complete in six to eight months.[58] The neurophysiological processes involved in recovery following acute paralytic poliomyelitis are quite effective; muscles are able to retain normal strength even if half the original motor neurons have been lost.[62] Paralysis remaining after one year is likely to be permanent, although modest recoveries of muscle strength are possible 12 to 18 months after infection.[58]

One mechanism involved in recovery is nerve terminal sprouting, in which remaining brainstem and spinal cord motor neurons develop new branches, or axonal sprouts.[63] These sprouts can

reinnervate orphaned muscle fibers that have been denervated by acute polio infection,[64] restoring the fibers' capacity to contract and improving strength.[65] Terminal sprouting may generate a few significantly enlarged motor neurons doing work previously performed by as many as four or five units:[34] a single motor neuron that once controlled 200 muscle cells might control 800 to 1000 cells. Other mechanisms that occur during the rehabilitation phase, and contribute to muscle strength restoration, include myofiber hypertrophy—enlargement of muscle fibers through exercise and activity—and transformation of type II muscle fibers to type I muscle fibers.[64][66]

In addition to these physiological processes, the body possesses a number of compensatory mechanisms to maintain function in the presence of residual paralysis. These include the use of weaker muscles at a higher than usual intensity relative to the muscle's maximal capacity, enhancing athletic development of previously little-used muscles, and using ligaments for stability, which enables greater mobility.[66]

[edit] Complications

Residual complications of paralytic polio often occur following the initial recovery process.[11] Muscle paresis and paralysis can sometimes result in skeletal deformities, tightening of the joints and movement disability. Once the muscles in the limb become flaccid, they may interfere with the function of other muscles. A typical manifestation of this problem is equinus foot (similar to club foot). This deformity develops when the muscles that pull the toes downward are working, but those that pull it upward are not, and the foot naturally tends to drop toward the ground. If the problem is left untreated, the Achilles tendons at the back of the foot retract and the foot cannot take on a normal position. Polio victims that develop equinus foot cannot walk properly because they cannot put their heel on the ground. A similar situation can develop if the arms become paralyzed.[67] In some cases the growth of an affected leg is slowed by polio, while the other leg continues to grow normally. The result is that one leg is shorter than the other and the person limps and leans to one side, in turn leading to deformities of the spine (such as scoliosis).[67] Osteoporosis and increased likelihood of bone fractures may occur. Extended use of braces or wheelchairs may cause compression neuropathy, as well as a loss of proper function of the veins in the legs, due to pooling of blood in paralyzed lower limbs.[39][68] Complications from prolonged immobility involving the lungs, kidneys and heart include pulmonary edema, aspiration pneumonia, urinary tract infections, kidney stones, paralytic ileus, myocarditis and cor pulmonale.[39][68]

[edit] Post-polio syndrome

Main article: Post-polio syndrome

Between 25% and 50% of individuals who survive paralytic polio in childhood develop additional symptoms decades after recovering from the acute infection,[69] notably new muscle weakness and extreme fatigue. This condition is known as post-polio syndrome (PPS) or post-polio sequelae.[70] The symptoms of PPS are thought to involve a failure of the over-sized motor units created during recovery from paralytic disease.[71][72] Factors that increase the risk of PPS include the length of time since acute poliovirus infection, the presence of permanent residual

impairment after recovery from the acute illness, and both overuse and disuse of neurons.[70] Post-polio syndrome is not an infectious process, and persons experiencing the syndrome do not shed poliovirus.[4]

[edit] Eradication

Disability-adjusted life year for poliomyelitis per 100,000 inhabitants.

no data

≤ 0.35

0.35-0.7

0.7-1.05

1.05-1.4

1.4-1.75

1.75-2.1

2.1-2.45

2.45-2.8

2.8-3.15

3.15-3.5

3.5-3.85

≥ 3.85

WHO 2002

Main article: Poliomyelitis eradication

While now rare in the Western world, polio is still endemic to South Asia and Nigeria. Following the widespread use of poliovirus vaccine in the mid-1950s, the incidence of poliomyelitis declined dramatically in many industrialized countries. A global effort to eradicate polio began in 1988, led by the World Health Organization, UNICEF, and The Rotary Foundation.[73] These efforts have reduced the number of annual diagnosed cases by 99%; from an estimated 350,000 cases in 1988 to a low of 483 cases in 2001, after which it has remained at a level of about 1,000 cases per year (1,606 in 2009).[74][75][76] Polio is one of only two diseases currently the subject of a global eradication program, the other being Guinea worm disease. So far, the only diseases completely eradicated by humankind are smallpox, which happened in 1979,[77] and rinderpest in 2010.[78] A number of eradication milestones have already been reached, and several regions of the world have been certified polio-free. The Americas were declared polio-free in 1994.[79] In 2000 polio was officially eliminated in 36 Western Pacific countries, including China and Australia.[80][81] Europe was declared polio-free in 2002.[82] As of 2012, polio remains endemic in only three countries: Nigeria, Pakistan, and Afghanistan,[74][83] although it continues to cause epidemics in other nearby countries due to hidden or reestablished transmission.[84] For example, despite eradication ten years prior, an outbreak was confirmed in China in September of 2011 involving a strain prevalent in neighboring Pakistan.[85] Since January 2011, there were no reported cases of the disease in India, and hence in February 2012, the country was taken off the WHO list of polio endemic countries. It is reported that if there are no cases of polio in the country for two more years, it will be declared as a polio-free country.[86][87]

Christopher Hitchens wrote that he learned in 2005 that in Northern Nigeria—a country which at that time was considered provisionally polio free—an Islamic Fatwah was issued declaring that the polio vaccine was a conspiracy by the United States and the United Nations against the Muslim faith, saying that the drops were designed to sterilize the true believers. Subsequently, polio reappeared in Nigeria and spread from there to several other countries.[88]

[edit] History

Main article: History of poliomyelitis

An Egyptian stele thought to represent a polio victim, 18th Dynasty (1403–1365 BC)

The effects of polio have been known since prehistory; Egyptian paintings and carvings depict otherwise healthy people with withered limbs, and children walking with canes at a young age.[5] The first clinical description was provided by the English physician Michael Underwood in 1789, where he refers to polio as "a debility of the lower extremities".[89] The work of physicians Jakob Heine in 1840 and Karl Oskar Medin in 1890 led to it being known as Heine-Medin disease.[90] The disease was later called infantile paralysis, based on its propensity to affect children.

Before the 20th century, polio infections were rarely seen in infants before six months of age, most cases occurring in children six months to four years of age.[91] Poorer sanitation of the time resulted in a constant exposure to the virus, which enhanced a natural immunity within the population. In developed countries during the late 19th and early 20th centuries, improvements were made in community sanitation, including better sewage disposal and clean water supplies. These changes drastically increased the proportion of children and adults at risk of paralytic polio infection, by reducing childhood exposure and immunity to the disease.[91]

Small localized paralytic polio epidemics began to appear in Europe and the United States around 1900.[6] Outbreaks reached pandemic proportions in Europe, North America, Australia, and New Zealand during the first half of the 20th century. By 1950 the peak age incidence of paralytic poliomyelitis in the United States had shifted from infants to children aged five to nine years, when the risk of paralysis is greater; about one-third of the cases were reported in persons over 15 years of age.[92] Accordingly, the rate of paralysis and death due to polio infection also increased during this time.[6] In the United States, the 1952 polio epidemic became the worst outbreak in the nation's history. Of nearly 58,000 cases reported that year 3,145 died and 21,269 were left with mild to disabling paralysis.[93] Intensive care medicine has its origin in the fight

against polio.[94] Most hospitals in the 1950s had limited access to iron lungs for patients unable to breathe without mechanical assistance. Respiratory centers designed to assist the most severe polio patients, first established in 1952 at the Blegdam Hospital of Copenhagen by Danish anesthesiologist Bjørn Ibsen, were the harbingers of subsequent intensive care units (ICU). (A year later, Ibsen would establish the world's first dedicated ICU.)[95]

The polio epidemics changed not only the lives of those who survived them, but also affected profound cultural changes; spurring grassroots fund-raising campaigns that would revolutionize medical philanthropy, and give rise to the modern field of rehabilitation therapy. As one of the largest disabled groups in the world, polio survivors also helped to advance the modern disability rights movement through campaigns for the social and civil rights of the disabled. The World Health Organization estimates that there are 10 to 20 million polio survivors worldwide.[96] In 1977 there were 254,000 persons living in the United States who had been paralyzed by polio.[97] According to doctors and local polio support groups, some 40,000 polio survivors with varying degrees of paralysis live in Germany, 30,000 in Japan, 24,000 in France, 16,000 in Australia, 12,000 in Canada and 12,000 in the United Kingdom.[96] Many notable individuals have survived polio and often credit the prolonged immobility and residual paralysis associated with polio as a driving force in their lives and careers.[98]

The disease was very well publicized during the polio epidemics of the 1950s, with extensive media coverage of any scientific advancements that might lead to a cure. Thus, the scientists working on polio became some of the most famous of the century. Fifteen scientists and two laymen who made important contributions to the knowledge and treatment of poliomyelitis are honored by the Polio Hall of Fame, which was dedicated in 1957 at the Roosevelt Warm Springs Institute for Rehabilitation in Warm Springs, Georgia, USA. In 2008 four organizations (Rotary International, the World Health Organization, the U.S. Centers for Disease Control and UNICEF) were added to the Hall of Fame.[99][100]

[edit] See also

List of poliomyelitis survivors March of Dimes Franklin D. Roosevelt's paralytic illness

[edit] Notes and references

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2. ^ a b c d Chamberlin SL, Narins B (eds.) (2005). The Gale Encyclopedia of Neurological Disorders. Detroit: Thomson Gale. pp. 1859–70. ISBN 0-7876-9150-X.

3. ^ a b c d Ryan KJ, Ray CG (eds.) (2004). "Enteroviruses". Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 535–7. ISBN 0-8385-8529-9.

4. ^ a b c d e f g h i j k l m Atkinson W, Hamborsky J, McIntyre L, Wolfe S (eds.) (2009). "Poliomyelitis" (PDF). Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book) (11th ed.). Washington DC: Public Health Foundation. pp. 231–44.

5. ^ a b c Paul JR (1971). A History of Poliomyelitis. Yale studies in the history of science and medicine. New Haven, Conn: Yale University Press. pp. 16–18. ISBN 0-300-01324-8.

6. ^ a b c Trevelyan B, Smallman-Raynor M, Cliff A (2005). "The Spatial Dynamics of Poliomyelitis in the United States: From Epidemic Emergence to Vaccine-Induced Retreat, 1910–1971". Ann Assoc Am Geogr 95 (2): 269–93. doi:10.1111/j.1467-8306.2005.00460.x. PMC 1473032. PMID 16741562.

7. ̂ Aylward R (2006). "Eradicating polio: today's challenges and tomorrow's legacy". Ann Trop Med Parasitol 100 (5–6): 401–13. doi:10.1179/136485906X97354. PMID 16899145.

8. ̂ Heymann D (2006). "Global polio eradication initiative". Bull. World Health Organ. 84 (8): 595. doi:10.2471/BLT.05.029512. PMC 2627439. PMID 16917643.

9. ̂ McNeil, Donald (February 1, 2011). "In Battle Against Polio, a Call for a Final Salvo". New York Times. Retrieved 1 Feb 2011.; excerpt, "... getting rid of the last 1 percent has been like trying to squeeze Jell-O to death. As the vaccination fist closes in one country, the virus bursts out in another .... The [eradication] effort has now cost $9 billion, and each year consumes another $1 billion."

10. ̂ Falconer M, Bollenbach E (2000). "Late functional loss in nonparalytic polio". American journal of physical medicine & rehabilitation / Association of Academic Physiatrists 79 (1): 19–23. doi:10.1097/00002060-200001000-00006. PMID 10678598.

11. ^ a b c Leboeuf C (1992) (PDF). The late effects of Polio: Information For Health Care Providers.. Commonwealth Department of Community Services and Health. ISBN 1-875412-05-0. Archived from the original on June 25, 2008. Retrieved 2008-08-23.

12. ^ a b c d e Frauenthal HWA, Manning JVV (1914). Manual of infantile paralysis, with modern methods of treatment.. Philadelphia Davis. pp. 79–101. OCLC 2078290.

13. ̂ Wood, Lawrence D. H.; Hall, Jesse B.; Schmidt, Gregory D. (2005). Principles of Critical Care (3rd ed.). McGraw-Hill Professional. p. 870. ISBN 0-07-141640-4.

14. ̂ Katz, Samuel L.; Gershon, Anne A.; Krugman, Saul; Hotez, Peter J. (2004). Krugman's infectious diseases of children. St. Louis: Mosby. pp. 81–97. ISBN 0-323-01756-8.

15. ^ a b c Ohri, Linda K.; Jonathan G. Marquess (1999). "Polio: Will We Soon Vanquish an Old Enemy?". Drug Benefit Trends 11 (6): 41–54. Archived from the original on February 5, 2005. Retrieved 2008-08-23. (Available free on Medscape; registration required.)

16. ^ a b c d e f Kew O, Sutter R, de Gourville E, Dowdle W, Pallansch M (2005). "Vaccine-derived polioviruses and the endgame strategy for global polio eradication". Annu Rev Microbiol 59: 587–635. doi:10.1146/annurev.micro.58.030603.123625. PMID 16153180.

17. ̂ Gorson KC, Ropper AH (September 2001). "Nonpoliovirus poliomyelitis simulating Guillain-Barré syndrome". Archives of Neurology 58 (9): 1460–4. doi:10.1001/archneur.58.9.1460. PMID 11559319.

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2. Poliomyelitis (polio) is a highly infectious viral disease, which mainly affects young children. The virus is transmitted through contaminated food and water, and multiplies in the intestine, from where it can invade the nervous system. Many infected people have no symptoms, but do excrete the virus in their faeces, hence transmitting infection to others.

3. Initial symptoms of polio include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. In a small proportion of cases, the disease causes paralysis, which is often permanent. Polio can only be prevented by immunization.

Poliomyelitis

Fact sheet N°114February 2012

Key facts

Polio (poliomyelitis) mainly affects children under five years of age. One in 200 infections leads to irreversible paralysis. Among those paralysed, 5% to 10% die

when their breathing muscles become immobilized. Polio cases have decreased by over 99% since 1988, from an estimated 350 000 cases then, to 1

352 reported cases in 2010. The reduction is the result of the global effort to eradicate the disease.

In 2012, only three countries (Afghanistan, Nigeria and Pakistan) remain polio-endemic, down from more than 125 in 1988.

Persistent pockets of polio transmission in northern Nigeria and the border between Afghanistan and Pakistan are the current focus of the polio eradication initiative.

As long as a single child remains infected, children in all countries are at risk of contracting polio. In 2009-2010, 23 previously polio-free countries were re-infected due to imports of the virus.

In most countries, the global effort has expanded capacities to tackle other infectious diseases by building effective surveillance and immunization systems.

Success hinges on financing the next steps of the global eradication initiative.

Polio and its symptoms

Polio is a highly infectious disease caused by a virus. It invades the nervous system, and can cause total paralysis in a matter of hours. The virus enters the body through the mouth and multiplies in the intestine. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs. One in 200 infections leads to irreversible paralysis (usually in the legs). Among those paralysed, 5% to 10% die when their breathing muscles become immobilized.

People most at risk

Polio mainly affects children under five years of age.

Prevention

There is no cure for polio, it can only be prevented. Polio vaccine, given multiple times, can protect a child for life.

Global caseload

Polio cases have decreased by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries then, to 1352 reported cases in 2010. In 2012, only parts of three countries in the world remain endemic for the disease - the smallest geographic area in history - and case numbers of wild poliovirus type 3 are down to lowest-ever levels.

The Global Polio Eradication Initiative

Launch

In 1988, the forty-first World Health Assembly, consisting then of delegates from 166 Member States, adopted a resolution for the worldwide eradication of polio. It marked the launch of the Global Polio Eradication Initiative, spearheaded by WHO, Rotary International, the US Centers for Disease Control and Prevention (CDC) and the United Nations Children’s Fund (UNICEF). This followed the certification of the eradication of smallpox in 1980, progress during the 1980s towards elimination of the poliovirus in the Americas, and Rotary International’s commitment to raise funds to protect all children from the disease.

Progress

Overall, since the Global Polio Eradication Initiative was launched, the number of cases has fallen by over 99%. In 2012, only three countries in the world remain polio-endemic. Persistent pockets of polio transmission in northern Nigeria and along the border between Afghanistan and Pakistan are key epidemiological challenges.

In 1994, the WHO Region of the Americas (36 countries) was certified polio-free, followed by the WHO Western Pacific Region (37 countries and areas including China) in 2000 and the WHO European Region (51 countries) in June 2002. In 2010, the European Region suffered its first importation of polio after certification. In 2011, the WHO Western Pacific Region also suffered an importation of poliovirus.

In 2009, more than 361 million children were immunized in 40 countries during 273 supplementary immunization activities (SIAs). Globally, polio surveillance is at historical highs, as represented by the timely detection of cases of acute flaccid paralysis.

Objectives

The objectives of the Global Polio Eradication Initiative are:

to interrupt transmission of wild poliovirus as soon as possible; to achieve certification of global polio eradication; to contribute to health systems development and strengthen routine immunization and

surveillance for communicable diseases in a systematic way.

Strategies

There are four core strategies to stop transmission of the wild poliovirus in areas that are affected by the disease or considered at high risk of re-infection:

high infant immunization coverage with four doses of oral poliovirus vaccine (OPV) in the first year of life;

supplementary doses of OPV to all children under five years of age during SIAs; surveillance for wild poliovirus through reporting and laboratory testing of all acute flaccid

paralysis (AFP) cases among children under fifteen years of age; targeted “mop-up” campaigns once wild poliovirus transmission is limited to a specific focal

area.

Before a WHO region can be certified polio-free, three conditions must be satisfied:

there are at least three years of zero polio cases due to wild poliovirus; disease surveillance efforts in countries meet international standards; and each country must illustrate the capacity to detect, report and respond to “imported” polio

cases.

Laboratory stocks must be contained and safe management of the wild virus in inactivated polio vaccine (IPV) manufacturing sites must be assured before the world can be certified polio-free.

The Independent Monitoring Board (IMB) evaluates on a quarterly basis the progress towards each of the major milestones of the Global Polio Eradication Initiative Strategic Plan 2010-2012, determine the impact of any 'mid-course corrections' that are deemed necessary, and advise on additional measures when appropriate.

Coalition

The Global Polio Eradication Initiative (GPEI) is spearheaded by WHO, Rotary International, CDC and UNICEF. The eradication of polio is about equity in health and the moral imperative of reaching every child with an available health intervention.

The polio eradication coalition includes governments of countries affected by polio; private sector foundations (e.g. United Nations Foundation, Bill & Melinda Gates Foundation); development banks (e.g. the World Bank); donor governments (e.g. Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Iceland, Ireland, Italy, Japan, Luxembourg, Malaysia, Monaco, the Netherlands, New Zealand, Norway, Oman, Portugal, Qatar, the Republic of Korea, the Russian Federation, Saudi Arabia, Spain, Sweden, Switzerland, Turkey, United Arab Emirates, the United Kingdom and the United States of America); the European Commission; humanitarian and nongovernmental organizations (e.g. the International Red Cross and Red Crescent societies and the Global Poverty Project) and corporate partners (e.g. Sanofi Pasteur and Wyeth). Volunteers in developing countries also play a key role: 20 million people have participated in mass immunization campaigns.

Priorities for polio eradication

As long as a single child remains infected with polio, children in all countries are at risk of contracting the disease.

To stop transmission of the wild poliovirus and optimize the benefits of polio eradication, the global priorities are:

Stopping wild poliovirus transmission in endemic countries

Polio today is more geographically restricted than ever before. The highest priority is reaching all children during SIAs in the four countries which have never stopped transmission of polio. To succeed, high levels of political commitment must be maintained at national, state/provincial and district levels. In 2010, a new strategic plan was launched, based on lessons learned in the past years and an independent evaluation of the major barriers to stopping polio transmission. This strategic plan is based on district-specific planning to address the unique challenges of each of the infected areas, fully exploiting new tools such as bivalent oral polio vaccine and strengthening health systems.

Putting an end to re-established transmission

Three countries - Angola, Chad and the Democratic Republic of the Congo - are classified as having 're-established transmission' because they have had ongoing transmission for over 12 months. These countries are treated with the same level of priority as the endemic countries. In early 2011, all three countries initiated emergency action plans to address the situation and fill operational gaps.

Preventing new outbreaks

Poliovirus has a habit of finding pockets of inadequately vaccinated children. As China, Congo, the Russian Federation and Tajikistan have learned, the poliovirus does not respect national borders. To minimize the risk of outbreaks from importation, countries must maintain high population immunity levels.

Closing the funding gap

Substantial financial resources are required to support polio eradication. However, in addition to the obvious humanitarian benefits, economic modelling has demonstrated the financial benefits of polio eradication to be at least US$ 40-50 billion. Success in carrying out the necessary vaccination campaigns and surveillance hinges on sufficient funds from financial stakeholders.

Impact of the initiative

More than eight million people who would otherwise have been paralysed are walking today because they have been immunized against polio since the initiative began in 1988.

By preventing a debilitating disease, the Global Polio Eradication Initiative is helping reduce poverty, and is giving children and their families a greater chance of leading healthy and productive lives.

By establishing the capacity to access children everywhere, more than two billion children worldwide have been immunized during SIAs, demonstrating that well-planned health interventions can reach even the most remote, conflict-affected or poorest areas.

Planning for SIAs provides key demographic data – “finding” children in remote villages and households for the first time, and "mapping" their location for future health services.

In most countries, the Global Polio Eradication Initiative has expanded the capacity to tackle other infectious diseases, such as avian influenza or Ebola, by building effective disease-reporting and surveillance systems, training local epidemiologists and establishing a global laboratory network. This capacity has also been deployed in health emergencies such as the 2010 floods in Pakistan and the 2011 drought in the Horn of Africa.

Routine immunization services have been strengthened by bolstering the cold chain, transport and communications systems for immunization. Improving these services helped to lay the groundwork for highly successful measles vaccination campaigns that have saved millions of young lives.

Vitamin A is often administered during polio SIAs. Since 1988, more than 1.2 million childhood deaths have been prevented through provision of vitamin A during polio SIAs.

On average, one in every 250 people in a country has been involved in polio immunization campaigns. More than 20 million health workers and volunteers have been trained to deliver OPV and vitamin A, fostering a culture of disease prevention.

Through the synchronization of SIAs, many countries have established a new mechanism for coordinating major cross-border health initiatives aimed at reaching all people – a model for regional and international cooperation for health.

Future benefits of polio eradication

Once polio is eradicated, the world can celebrate the delivery of a major global public good that will benefit all people equally, no matter where they live. Economic modelling has found that the eradication of polio in the next five years would save at least US$ 40-50 billion, mostly in low-income countries

For more information contact

WHO Media centreTelephone: +41 22 791 2222 E-mail: mediainquiries@who.int

Poliomyelitis

Poliomyelitis is a viral disease that can affect nerves and can lead to partial or full paralysis.

Causes

Poliomyelitis is a disease caused by infection with the poliovirus. The virus spreads by:

Direct person-to-person contact Contact with infected mucus or phlegm from the nose or mouth Contact with infected feces

The virus enters through the mouth and nose, multiplies in the throat and intestinal tract, and then is absorbed and spread through the blood and lymph system. The time from being infected with the virus to developing symptoms of disease (incubation) ranges from 5 - 35 days (average 7 - 14 days).

Risks include:

Lack of immunization against polio Travel to an area that has experienced a polio outbreak

In areas where there is an outbreak, those most likely to get the disease include children, pregnant women, and the elderly. The disease is more common in the summer and fall.

Between 1840 and the 1950s, polio was a worldwide epidemic. Since the development of polio vaccines, the incidence of the disease has been greatly reduced. Polio has been wiped out in a number of countries. There have been very few cases of polio in the Western hemisphere since the late 1970s. Children in the United States are now routinely vaccinated against the disease.

Outbreaks still occur in the developed world, usually in groups of people who have not been vaccinated. Polio often occurs after someone travels to a region where the disease is common. As a result of a massive, global vaccination campaign over the past 20 years, polio exists only in a few countries in Africa and Asia.

Symptoms

There are three basic patterns of polio infection: subclinical infections, nonparalytic, and paralytic. About 95% of infections are subclinical infections, which may not have symptoms.

SUBCLINICAL INFECTION SYMPTOMS

General discomfort or uneasiness (malaise) Headache Red throat

Slight fever Sore throat Vomiting

People with subclinical polio infection might not have symptoms, or their symptoms may last 72 hours or less.

Clinical poliomyelitis affects the central nervous system (brain and spinal cord), and is divided into nonparalytic and paralytic forms. It may occur after recovery from a subclinical infection.

NONPARALYTIC POLIOMYELITIS

Back pain or backache Diarrhea Excessive tiredness, fatigue Headache Irritability Leg pain (calf muscles) Moderate fever Muscle stiffness Muscle tenderness and spasm in any area of the body Neck pain and stiffness Pain in front part of neck Pain or stiffness of the back, arms, legs, abdomen Skin rash or lesion with pain Vomiting

Symptoms usually last 1 - 2 weeks.

PARALYTIC POLIOMYELITIS

Fever 5 - 7 days before other symptoms Abnormal sensations (but not loss of sensation) in an area Bloated feeling in abdomen Breathing difficulty Constipation Difficulty beginning to urinate Drooling Headache Irritability or poor temper control Muscle contractions or muscle spasms in the calf, neck, or back Muscle pain Muscle weakness that is only on one side or worse on one side

o Comes on quicklyo Location depends on where the spinal cord is affectedo Worsens into paralysis

Sensitivity to touch; mild touch may be painful

Stiff neck and back Swallowing difficulty

Exams and Tests

The health care provider may find:

Abnormal reflexes Back stiffness Difficulty lifting the head or legs when lying flat on the back Stiff neck Trouble bending the neck

Tests include:

Cultures of throat washings, stools, or cerebrospinal fluid (CSF) Routine CSF examination Test for levels of antibodies to the polio virus

Treatment

The goal of treatment is to control symptoms while the infection runs its course.

People with severe cases may need lifesaving measures, especially breathing help.

Symptoms are treated based on their severity. Treatment may include:

Antibiotics for urinary tract infections Medications (such as bethanechol) for urinary retention Moist heat (heating pads, warm towels) to reduce muscle pain and spasms Painkillers to reduce headache, muscle pain, and spasms (narcotics are not usually given

because they increase the risk of breathing trouble) Physical therapy, braces or corrective shoes, or orthopedic surgery to help recover muscle

strength and function

Outlook (Prognosis)

The outlook depends on the form of the disease (subclinical, nonparalytic, or paralytic) and the body area affected. If the spinal cord and brain are not involved, which is the case more than 90% of the time, complete recovery is likely.

Brain or spinal cord involvement is a medical emergency that may result in paralysis or death (usually from respiratory problems).

Disability is more common than death. Infection that is located high in the spinal cord or in the brain increases the risk of breathing problems.

Possible Complications

Aspiration pneumonia Cor pulmonale (a form of heart failure found on the right side of the circulation system) High blood pressure Kidney stones Lack of movement Lung problems Myocarditis Paralytic ileus (loss of intestinal function) Permanent muscle paralysis, disability, deformity Pulmonary edema Shock Urinary tract infections

Post-polio syndrome is a complication that develops in some patients, usually 30 or more years after they are first infected. Muscles that were already weak may get weaker. Weakness may also develop in muscles that were not affected before.

When to Contact a Medical Professional

Call your health care provider if:

Someone close to you has developed poliomyelitis and you haven't been vaccinated You develop symptoms of poliomyelitis Your child's polio immunization (vaccine) is not up to date

Prevention

Polio immunization (vaccine) effectively prevents poliomyelitis in most people (immunization is over 90% effective).

Alternative Names

Polio; Infantile paralysis; Post-polio syndrome

References

Modlin JF. Poliovirus. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 171.

Silver JK. Post-poliomyelitis syndrome. In: Frontera WR, Silver JK, Rizzo Jr TD, eds. Essentials of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2008: chap 137.

Update Date: 8/24/2011

Updated by: Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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Polio and Post-Polio Syndrome

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Poliomyelitis

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Aspiration pneumonia Cor pulmonale Incidence Intestinal obstruction Kidney stones Lymph system Muscle function loss Myocarditis Pulmonary edema Respiratory Shock Stress and anxiety Tonsillectomy Poliomyelitis is an enteroviral infection that can manifest in 4 different forms: inapparent

infection, abortive disease, nonparalytic poliomyelitis, and paralytic disease. Before the

19th century, poliomyelitis occurred sporadically. During the 19th and 20th centuries, epidemic poliomyelitis was more frequently observed, reaching its peak in the mid 1950s. The worldwide prevalence of this infection has decreased significantly since then because of aggressive immunization programs. Eradication of this disease during the present decade is a top priority for the World Health Organization (WHO).[1]

Polio eradication this week: 

In India, while no cases have been reported since January 2011, ongoing eradication activities are being implemented to secure the gains achieved. Large-scale immunization activities and active surveillance for acute flaccid paralysis (AFP) cases is continuing. Every month, approximately 5,000 AFP cases are identified and investigated across the country. The combination of high population immunity levels and strong disease surveillance is the best way for polio-free countries to protect themselves from polio.

Dr Thomas Frieden, Director of the US Centers for Disease Control and Prevention (CDC), visited Nigeria this week, to discuss the importance of polio eradication with the Honourable Federal Minister of Health Professor CO Onyebuchi Chukwu, Minister of State for Health Dr Mohammad Ali Pate, the Deputy Governor of Kano state, and in-country partners.

Polio this week - As of 14 March 2012

UK Prime Minister Cameron honoured as Polio Eradication Champion by Rotary – this week, Prime Minister of the United Kingdom David Cameron, is being recognized as a Polio Eradication Champion award, for his leadership and dedication to a polio-free world. "We have a once-in-a-generation opportunity to rid the world of the evil of polio," said Prime Minister Cameron in a statement. "The commitment of Britain and the Global Polio Eradication Initiative, with the support of millions of Rotarians, has helped bring this crippling and often deadly disease to the brink of eradication." The award, to be presented by Rotary International President Kalyan Banerjee, will be received by International Development Secretary Andrew Mitchell on behalf of Cameron, at a reception at the House of Commons. The Polio Eradication Champion Award is the highest honour Rotary presents to heads of state, health agency leaders and others who have made significant contributions to the global polio eradication effort. "On behalf of Rotary's 1.2 million members worldwide, I am honored to recognize the commitment of Prime Minister Cameron for his outstanding support of efforts to eradicate polio," said Banerjee. "My own country, India, has just surpassed the milestone of a year without polio. We would not be so close to achieving the goal of a polio free world without the longstanding support and continued leadership of the United Kingdom. We encourage

other G8 countries to follow the UK's lead in continuing their support so that the world will soon be polio free." The UK has been a strong supporter of the global polio eradication initiative with contributions and commitments totaling more than US$960 million through 2012. The Global Polio Eradication Initiative continues to face a dangerous funding gap of US$1.09 billion through end-2013, an amount that urgently needs to be filled.

Media reports of acute flaccid paralysis case in India: In India, while no cases have been reported since January 2011, eradication activities are continuing strongly to secure the gains achieved. Large-scale immunization activities are being conducted in March, and active surveillance for acute flaccid paralysis (AFP) cases is continuing. As such, reports of AFP cases is not unexpected or unusual – quite the opposite, in fact, it means disease surveillance is working. Every month, approximately 5,000 AFP cases are identified and investigated across the country. Symptoms of AFP are caused by a number of different pathogens, poliovirus being just one of many potential causes. Strong disease surveillance means that at least two AFP cases per 100,000 population (aged <15 years) are identified, to ascertain the presence or absence of poliovirus circulation in a given environment. The extensive immunization and surveillance activities ongoing in India will need to continue, as long as endemic poliovirus has not been eradicated in the remaining three countries. The combination of high population immunity levels and strong disease surveillance is the best way for a country to minimize the risk and consequences of polio re-emergence or re-introduction.

Dr Thomas Frieden, Director of the US Centers for Disease Control and Prevention (CDC), visited Nigeria this week, to discuss the importance of polio eradication with the Honourable Federal Minister of Health Professor CO Onyebuchi Chukwu, Minister of State for Health Dr Mohammad Ali Pate, the Deputy Governor of Kano state, and in-country partners.

Wild Poliovirus (WPV) cases

Total cases Year-to-date 2012 Year-to-date 2011 Total in 2011* 

Globally 25  55 650 

- in endemic countries 24  18  341 

- in non-endemic countries 1 37  79 

Case breakdown by country

CountriesYear-to-date 2012 Year-to-date 2011

Total in 2011*   

Date of most 

 recent case  WPV1 

  WPV3  

 W1W3 

  Total  

  WPV1 

  WPV3    W1W3 

  Total  

Pakistan 12   1  13  15      15  198  18-Feb-12 

Afghanistan 5      5  1      1  80  15-Feb-12 

Nigeria 5  1    6  1      1  62  08-Feb-12 

India         1     1  1  13-Jan-11 

CountriesYear-to-date 2012 Year-to-date 2011

Total in 2011*   

Date of most 

 recent caseChad 1      1  12  1    13  132  09-Jan-12 

DR Congo         21      21  93  20-Dec-11 

Niger               5 12-Dec-11 

CAR               4 08-Dec-11 

China               21  09-Oct-11 

Guinea                 3 03-Aug-11

Kenya                 1  30-Jul-11

Côte d'Ivoire                 36  24-Jul-11 

Angola         1      1  5  07-Jul-11 

Mali                 7  23-Jun-11 

Congo         1     1 1  22-Jan-11 

Gabon         1     1 1 15-Jan-11

Total 23 1  1  25  54 1  0  55  650   

Total in endemic countries     

22 1  1  24  18  0  0  18 341   

Total outbreak     1 0  0  1  36  1  0  37  79   

Data in WHO as of 14 Mar 2011 for 2011 data and 13 Mar 2012 for 2012 data.

Afghanistan

One new case was reported in the past week (type WPV1 from Paktya province), bringing the total number of cases for 2012 to five. This is the most recent case in the country, with onset of paralysis on 15 February. The total number of cases for 2011 remains 80.

This newly-reported case from Paktya province (Jadran district) is in the east of the country (across the border with Pakistan), an area which has not seen a polio case in more than ten years. Genetic sequencing is ongoing to determine the origin of this case, ie whether it is linked to endemic transmission from the country's Southern Region, or cross-border transmission from Pakistan.

While endemic transmission continues to be highly focalized to high-risk districts in Southern Region (due primarily to hampered access associated with insecurity), it is critical that high population immunity levels are maintained in all other provinces of the country to prevent polio from regaining a foothold in non-endemic areas of Afghanistan.

For this reason, the upcoming national immunization days - scheduled for 25-27 March - are critical. Preparations are underway to ensure the highest quality activity can be

achieved. Technical support is being scaled up to help with planning and monitoring of the activity in the highest-risk districts of Southern Region. Efforts are already underway to engage all parties, to try to secure increased safe passage of vaccination teams to all communities.

A national polio emergency action plan is currently being finalized by the Ministry of Health and partners. The plan aims to address ongoing challenges, including by introducing 'permanent polio teams' in high-risk, security-compromised districts. Such teams would be able to circulate on a rolling basis, in between large-scale national and subnational immunization days, and administer additional doses of OPV to communities living in otherwise hard-to-reach areas.

Nigeria

One new case was reported in the past week with onset on 27 January (type WPV1 from Zamfara State), bringing the total number of cases for 2012 to six. The most recent case had onset of paralysis on 8 February (type WPV1 from Jigawa State). The total number of cases for 2011 remains 62.

The security situation continues to be assessed in the country, including in close collaboration with UNDSS. Strategies to ensure ongoing implementation of polio activities continue to be implemented.

The use of global position systems (GPS) to more adequately track and assess individual vaccination team performance (in relation to pre-prepared microplans) is being evaluated this month in Jigawa state.

Following last week's official launching of the Presidential Task Force, Dr Mohammad Pate, Minister of State for Health and Chair of the Presidential Task Force, convened a meeting this week with chairpersons of the State Task Forces to discuss concrete measures all parties need to take to fully and rapidly implement the national polio emergency plan.

The next Expert Review Committee on Polio Eradication and Routine Immunization will meet on 28-29 March, to review latest epidemiology and put forward key recommendations for implementation of the national polio emergency plan.

Preparations are ongoing for the next national immunization plus days, on 31 March to 3 April. Technical support is being prioritized to key local government areas in the eight identified high-risk states in the north.

Pakistan

One new case was reported in the past week (type WPV1 from Federally Administrated Tribal Areas), bringing the total number of cases for 2012 to 13. This is the most recent case in the country, with onset of paralysis on 18 February. The total number of cases for 2011 remains 198.

This latest case is in a district with confirmed transmission of both wild poliovirus type 1 and wild poliovirus type 3.

Subnational immunization days are ongoing this week to reach more than 23 million children under the age of five years with bivalent OPV.

Extensive preparations, including at the critical district and union-council level, had been conducted for the immunization campaign. Part of preparations included ensuring engagement of district heads during the activity, including the monitoring of the campaign. As part of the augmented national polio emergency plan, participation of leaders at this critical level is now being tracked and actively evaluated.

The campaigns were officially launched and supported both nationally and subnationally by key supporters and partners, including by the Prime Minister’s Focal Person for Polio Eradication Ms Shahnaz Wazir Ali and the Chairman Senate Mr. Nayyar Hussain Bukhari in Islamabad. Provincial inaugurations were held by Senator Farhat Abbas in Peshawar and the renowned religious leader Maulana Samiul Haq at Jamia Haqqania (religious school) in Nowshera (Khyber Pakhtunkhwa). Provincial Health Minister Dr. Sagheer Ahmed and the eminent social worker Mr. Abdul Sattar Edhi launched the activity in Karachi, while Federal Minister for Religious Affairs Syed Khurshid Ahmed Shah presided over a conference in Karachi on 11 March, urging religious leaders to publicly support the polio eradication effort.

Significant social mobilization activities preceeded the campaign launches, including through a press briefing by parliamentarians regarding vaccine safety; frequent messages distributed throughout the campaign via electronic media; and, electronic and print media advertisements placed, highlighting the need for OPV to protect from lifelong polio-paralysis.

The Technical Advisory Group will convene on 21-22 March to review epidemiology of polio transmission and impact of the augmented national polio emergency plan. The group will also discuss a number of technical issues, such as potentially and periodically immunizing older age groups (<15 years) in and near conflict-affected areas with access problems.

Angola

No new cases were reported in the past week. No cases have been reported in 2012. The country has reported a total of five cases in 2011, the most recent of which had onset of paralysis on 7 July in Uige in the country's north.

Plans are underway to introduce environmental surveillance in key areas, notably in Luanda, in April. Such activities will be key to supplementing surveillance for acute flaccid paralysis (AFP) cases, and provide a clearer epidemiological picture.

Mop-up immunization activities are currently ongoing in key municipalities, notably in and around Luanda, to further boost population immunity levels.

Supplementary immunization activities are planned for 30 March–1 April, May, and 22–24 June.

Chad and CAR

No new cases were reported in the past week. The total number of cases for 2012 remains one (from Chad). The most recent case was a WPV1 case in Chad (Logone Oriental), with onset of paralysis on 9 January. The total number of cases for 2011 remains 136

(132 in Chad and four in Central African Republic). A November case from Cameroon has now been officially re-classified as a Nigerian case.

In 2012, Chad is the only non-endemic country to report polio cases. The Honourable Minister of Health last week convened an urgent meeting with all regional delegates, to review the performance of the February immunization activity and discuss corrective steps which need to be taken.

Per recommendations from the recent Technical Advisory Group in February, efforts are underway to help fill residual subnational surveillance gaps in the country.

Supplementary immunization activities in Chad that were planned for 16–18 March and 13–15 April have been shifted by 10 days, respectively. The March activity will now take place on 29 March.

With ongoing, active transmission in both Chad and Nigeria, immunization activities continue to be planned both in Cameroon and in Central African Republic, to minimize the risk and consequences of reinfection.

In the Central African Republic, NGOs are increasingly being engaged to help support eradication efforts. At the same time, a three-month outbreak response assessment is currently underway in the country, to fully assess the impact of outbreak response activities and the risk to populations from any potential renewed international spread of polio.

China

No new cases were reported in the past week. No cases have been reported in 2012. China has a total of 21 cases for 2011, all WPV1. The most recent had onset of paralysis on 9 October from Akesu prefecture, Xinjiang province, western China.

Democratic Republic of the Congo (DRC)

No new cases were reported in the past week. No cases have been reported in 2012. The total number of cases for 2011 is 93 (all WPV1). The most recent case had onset of paralysis on 20 December in Maniema province.

An in-depth assessment of national surveillance sensitivity was conducted in February in DR Congo. Overall, despite challenges such as inaccessibility, insecurity and vast geographic expanses, surveillance is functioning. However, some subnational variation was noted, particularly in areas with recent polio transmission, such as Bandundu, Bas-Congo, Katanga and Maniema, as well as Equateur, Orientale and South Kivu. Rapid subnational reviews are now being planned, and measures implemented to help fill residual subnational surveillance gaps. This will include ensuring training of surveillance staff and obtaining more accurate population denominator data (against which a more accurate non-polio AFP rate can then be calculated).

An additional round of supplementary immunization activities is planned for the end of March. The activity is being conducted with trivalent OPV, and will mean that four campaigns have been held in Katanga since the most recent wild poliovirus case (using a combination of bivalent and trivalent OPV), and in response to last year's type 2 cVDPV, two doses of trivalent OPV in the province will have been administered to communities.

It is an appropriate response, using a strategic mix of vaccines, to address both wild poliovirus type 1 and the cVDPV type 2.

Additional national immunization days are anticipated for May and June.

West Africa

No new cases were reported in the past week. The total number of cases for 2011 in West Africa remains 51 (36 from Côte d'Ivoire, three from Guinea, seven from Mali, and five from Niger). All cases are WPV3, except for three WPV1 cases from Niger.

National Immunization Days are planned for 23–26 March in key countries of the region. In Niger, a comprehensive post outbreak response assessment is ongoing.

Poliomyelitis (infantile paralysis, polio)

Last Reviewed: January 2012

Versión en español Poliomielitis - Medline Plus Información de Salud para Usted

What is polio?

Polio is a viral disease which may affect the spinal cord causing muscle weakness and paralysis. The polio virus enters the body through the mouth, usually from hands contaminated with the stool of an infected person. Polio is more common in infants and young children and occurs under conditions of poor hygiene. Paralysis is more common and more severe when infection occurs in older individuals.

Who gets polio?

The number of cases of polio decreased dramatically in the United States following the introduction of the polio vaccine in 1955 and the development of a national vaccination program. The last cases of naturally occurring polio in the United States were in 1979. Most of the world's population resides in areas considered free of wild poliovirus circulation. Travelers to countries where polio cases still occur should know they are immune or be fully immunized. In 2008, these areas include Africa, Southeast Asia, and the Eastern Mediterranean.

How is polio spread?

Polio is spread when the stool of an infected person is introduced into the mouth of another person through contaminated water or food (fecal-oral transmission). Oral-oral transmission by way of an infected person's saliva may account for some cases.

When and for how long is a person able to spread polio?

Patients are most infectious from seven to ten days before and after the onset of symptoms. However, patients are potentially contagious as long as the virus is present in the throat and feces. The virus persists in the throat for approximately one week after the onset of illness and is excreted in the feces for three to six weeks.

What are the symptoms of polio?

Up to 95 percent of people infected with polio have no symptoms. However, infected persons without symptoms can still spread the virus and cause others to develop polio. About four to five percent of infected people have minor symptoms such as fever, muscle weakness, headache, nausea and vomiting. One to two percent of infected persons develop severe muscle pain and stiffness in the neck and back. Less than one percent of polio cases result in paralysis.

How soon after infection do symptoms appear?

The incubation period is commonly six to 20 days with a range of three to 35 days.

What are the complications associated with polio?

Complications include paralysis, most commonly of the legs. Paralysis of the muscles of breathing and swallowing can be fatal.

What is the treatment for polio?

There is presently no cure for polio. Treatment involves supportive care.

Does past infection with polio make a person immune?

There are three types of polio virus. Lifelong immunity usually depends on which type of virus a person contracts. Second attacks are rare and result from infection with a polio virus of a different type than the first attack.

Is there a vaccine for polio?

There are two types of polio vaccine: trivalent oral polio vaccine (tOPV), given by mouth, and inactivated polio vaccine (IPV), given as an injection. As of January 2000, tOPV is no longer recommended for immunization in the United States. The recommended schedule for childhood immunization is for IPV to be given at two, four, and six to 18 months of age and between four to six years of age. Adults traveling to countries where polio cases are occurring should review their immunization status to make sure they are immune.

In New York State, polio vaccine is required for all children enrolled in pre-kindergarten programs and schools.

How can polio be prevented?

Maintaining high levels of polio immunization in the community is the single most effective preventive measure.

What is post-polio syndrome (PPS)?

PPS is a condition that affects polio survivors ten to 40 years after recovery from an initial infection. PPS is characterized by further weakening of muscles that were previously affected by the polio infection. Symptoms include fatigue, slowly progressive muscle weakness and deterioration. Joint pain and bone deformities are common. PPS is generally not life-threatening. There is no known cause or effective treatment for PPS.