vector-borne diseases s. sears, md. lyme disease multisystem inflammatory disease causes by...

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Vector-borne diseases S. Sears, MD Slide 2 Lyme disease Multisystem inflammatory disease Causes by spirochetes Borrelia burgdorferi Spread by Ixodes ticks I. scapularis Eastern,North central and Southern United States I. pacificus Western United States I. ricinus Europe I. persulcatus Asia Transmission Bite of an infected nymph in the spring-really small, barely even know youve been bitten Preferred host White-tailed deer Slide 3 Borrelia burgdorferi Slide 4 Ixodes scapularis Slide 5 Clinical manifestations Early localized disease Occurring few days to one month after the tick bite Early disseminated disease Occurring days to 10 months after the tick bite Late or chronic disease Occurring months to years after the tick bite Slide 6 Early localized disease Erythema migrans 50-70% of patients Found Near axilla Inguinal region Behind the knees Belt line Asymptomatic May burn or itch Expands over the course a few days with central clearing Associated symptoms Fatigue Malaise Lethargy Headache Stiff neck Myalgias Arthralgias Lymphadenopathy Slide 7 Erythema migrans Slide 8 Early disseminated disease Carditis : 8 -10% of patients Conduction defects Cardiomyopathy or myopericarditis Neurologic disease :10% of patients Lymphocytic meningitis Encephalitis Cranial neuropathy (often bilateral facial) Peripheral neuropathy Radiculoneuropathy Myelitis Musculoskeletal involvement : 50% of patients Migratory polyarthritis Skin involvement Erythema nodosum Lymphadenopathy Eye involvement Conjunctivitis Iritis Retinitis Vitritis Choroiditis Hepatitis Microhematuria with proteinuria Slide 9 Late or chronic disease Musculoskeletal symptoms 50% : migratory polyarthritis 10% : chronic monoarthritis (knee) Neurologic disease (incidence not established) Neuroborrelosis Encephalopathy Neurocognitive dysfunction Peripheral neuropathy Encephalopathy Encephalomyelitis Peripheral neuropathy Ataxia Dementia Psychiatric disturbances Cutaneous involvement Acrodermatitis chronica atrophicans Morphea (localized scleroderma-like lesions) Slide 10 Acrodermatitis chronica atrophicans Slide 11 Diagnosis Centers of Disease Control and Prevention criteria Presence of erythema migrans OR At least one late manifestation Plus laboratory confirmation Late manifestations can include if not explained by another disease Musculoskeletal system Chronic arthritis Not Chronic progressive arthritis Chronic symmetrical arthritis Fibromyalgia Nervous system Lymphocytic meningitis Cranial neuritis Encephalomyelitis CSF confirmation of antibody against B. burgdorferi Not Headache Fatigue paresthesias Slide 12 Diagnosis Serologic tests Used to confirm the diagnosis Diagnosis make on clinical grounds Two-rest step approach Sensitive enyzme-linked immunosorbent assay (ELISA) Followed by Western immunoblot If ELISA positive-test Western blot If ELISA negative-no Western blot Same sample tested by each test If < 4 weeks illness - IgM and IgG tested If > 4 weeks illness - IgG tested Synovial fluid or CSF Tested for the antibodies to B.burgdorferi Antibiotics in early disease may prevent seroconversion Prior vaccine interferes with the test (vaccine no longer available) Slide 13 Treatment Early disease Erythema migrans < 10% do not respond Do not use macrolides For areas also endemic for human ehrlichiosis use doxycycline Doxycycline 100mg po bid for 10-21 days Amoxicillin 500mg po tid for 14-21 days Cefuroxime 500mg po bid for 14-21 days Disseminated disease Cardiac First degree AV block Doxycycline 100mg po bid for 14-21 days Amoxicillin 500mg po tid for 14-21 days Cefuroxime 500mg po bid for 14-21 days Late disease Ceftriaxone 2g IV daily for 14-21 days Slide 14 Treatment Disseminated disease Neurologic disease Early Isolated facial nerve palsy Doxycycline 100mg po bid for 14-21 days Amoxicillin 500mg po tid for 14-21 days Cefuroxime 500mg po bid for 14-21 days More serious disease Early or late Meningitis Radiculopathy Encephalitis Ceftriaxone 2 g IV daily for 14-28 days Arthritis No evidence of neurologic disease Doxycycline 100mg po bid for 28 days Amoxicillin 500mg po tid for 28 days Cefuroxime 500mg po bid for 28 days With neurologic disease Ceftriaxone 2g IV daily for 14-28 days Slide 15 Outcome Treatment with standard antibiotics generally successful 10 % experience treatment failure Non-specific symptoms may linger Asymptomatic seropositive patients Recommendation not to treat Slide 16 Human ehrlichiosis Ehrlichiae Obligate intracellular bacteria Grow in membrane bound vacuoles Human and animal leukocytes Diseases Human monocytic ehrlichiosis (HME) Caused by Ehrlichia chaffeensis Human granulocytic anaplasmosis (HGA) Caused by Anaplasma phagocytophilum Occurs in spring and summer In southeastern, southcentral,mid-Atlantic United States Tick vector E.chaffeensis - Lone star tick (Amblyomma americanum) A.phagocytophilum - Ixodes scapularis Animal reservoir HME - white tail deer HGA - deer and white-footed mouse Slide 17 Ehrlichia chaffeensis Slide 18 Lone star tick Slide 19 Clinical manifestations Incubation period 1-2 weeks prior to presentation of symptoms Fever can persist for 2 months Nonspecific Malaise Myalgia Headache Chills Nausea Vomiting Arthralgias Cough Maculopapular or petechial rash Neurologic Mental status changes Stiff neck Clonus Complications Seizures Coma Congestive heart failure Pericardial effusion Slide 20 Rash Slide 21 Investigations Laboratory findings Leukopenia Thrombocytopenia Anemia Increased liver function tests CSF lymphocytic pleocytosis Diagnosis Indirect fluorescent antibody (IFA) test Examination of peripheral blood or buffy coat PCR for HME and HGA Immunochemical staining of ehrlichial/anaplasmal antigens in tissue Slide 22 Treatment Drug of choice Doxycycline IV or oral 100 mg bid for 10 days Intolerance to doxycycline Use rifampin 300mg po bid for 7-10 days Slide 23 Outcome Mortality rates HME - 2 to 5 percent HGA - 7 to 10 percent Life-threatening disease In patients co-infected with HIV Solid organ transplant recipients Prevention Tick repellants Tick removal Slide 24 Babesiosis Tick borne illness Protozoa of the family Babesiidae Animal reservoir Rodents and cattle Human disease Due to Babesia microti Enters the red blood cells and causes hemolysis Vector Ixodid tick Occurs northeast coast of the United States Slide 25 Clinical manifestations Incubation period Following a tick bite 1-3 weeks After blood transfusion 6-9 weeks Symptoms Fever Chills Sweats Myalgia Arthralgia Nausea Vomiting Fatigue Physical exam Splenomegaly Hepatomegaly Jaundice Slide 26 Severe disease High-level parasitemia (> 10 percent) Significant hemolysis ( plus DIC) Renal,hepatic, pulmonary compromise Risk factors Age over 50 years Asplenia Underlying malignancy Immunosuppressive therapy HIV/AIDS Slide 27 Diagnosis Laboratory Anemia Thrombocytopenia Conjugated hyperbilirubinemia Confirmation Blood smear Intraerythrocytic parasites PCR Serology Indirect immunofluorescent antibody test Slide 28 Babesia microti Slide 29 Treatment First-line treatment 7-10 days Clindamycin-quinine Or atovaquone-azithromycin Dosing Atovaquone - 750 mg po q 12 hrs Azithromycin - 500-1000 mg po x1 then 250 mg po daily Clindamycin - 600 mg po tid or 300 mg IV qid Quinine - 650 mg po q6hrs Severe disease Antibiotics Plus exchange transfusion Until parasitemia is < 5 percent Outcome is variable with level of disease Slide 30 Malaria Human malaria caused by species Plasmodia P. falciparum P. vivax P. ovale P. malariae Predominates Tropical Africa Southeast Asia Haiti South America Dominican Republic Central America Middle East India Transmission Bite of Anopheles mosquito Congenital Blood transfusion Contaminated needles Transplantation Slide 31 Anopheles mosquito Slide 32 Malaria All four malaria parasites Digest red blood cell proteins and hemoglobin Results in hemolysis and increased splenic clearance Liver and spleen enlarge over time Thrombocytopenia from increased splenic clearance P. Falciparum Forms stick knobs Forms rosettes Results in obstruction of blood flow Protection against malaria Sickle cell genetic alterations Alpha thalassemia Beta thalassemia Ovalocytes Immunity Partial immunity may occur in those in endemic areas Slide 33 Cycle of malaria Slide 34 Clinical manifestations Incubation period 1-4 weeks Symptoms Chills Sweats Headache Myalgias Fatigue Nausea Abdominal pain Vomiting Diarrhea Cough Signs Anemia Thrombocytopenia Splenomegaly Hepatomegaly Jaundice Splenic rupture Slide 35 Clinical manifestations P. falciparum Associated with transient increases in HIV viral load Cerebral malaria Impaired state of consciousness Seizures Risk factors Age Pregnancy Poor nutritional status HIV infection Prior splenectomy Complications Renal failure ARDS Hypoglycemia Anemia Bleeding Gastroenteritis P. vivax and ovale Liver forms-late relapses P. malariae GN from chronic immune complex formation and deposition Slide 36 Diagnosis Light microscopy Stained thick and thin blood smear Thick smear Malaria Thin smear Morphologic features Parasite density estimation Fluorescent microscopy Antigen detection PCR- DNA / RNA Slide 37 Blood smear Slide 38 Treatment Supportive measures Antimalarial medications Mechanisms of antimalarial drugs Quinoline derivatives Chloroquine,quinine,quinidine,mefloquine Inhibit heme polymerase activity Accumulation of free heme is toxic to parasites Antifolates Pyrimethamine,sulfonamides,dapsone Kill intrahepatic forms of the parasite Artemisinin derivatives Artemisinin,artemether,artesunate Produce free radical that damage parasite proteins Antimicrobials Clindamycin,atovaquone,tetracyclines Kill blood parasites Slide 39 Treatment Chloroquine-sensitive P.vivax P.ovale P. malariae Chloroquine 10mg base/kg (max 600mg base) Followed by 5mg/kg base (max 300mg base) At 6, 24,and 48 hours Cure rates 95% Chloroquine resistant P. vivax Mefloquine or quinine PLUS doxycycline Pr

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