remember remember autoinfection mode of infection infective stage definitive host intermediate host...

RememberRemember• Autoinfection

• Mode of infection

• Infective stage

• Definitive host

• Intermediate host

•Type of parasites

•Source of infection

•Vector

•transmission

Location in humansLocation in humansTrematodes (flukes)Trematodes (flukes)

BloodBloodSchistosoma hematobiumSchistosoma hematobium

S. mansoniS. mansoni

S. japonicumS. japonicum

S. mekongiS. mekongi

s. intercalatums. intercalatum

LiverLiverClonorchis sinensisClonorchis sinensis

Dicrocoelium dendriticumDicrocoelium dendriticum

Opisthorchis felineusOpisthorchis felineus

O.ViverriniO.Viverrini

Fasciola hepaticaFasciola hepatica

f.giganticaf.gigantica

IntestineIntestineFasciolopsis buskiFasciolopsis buski

Echinostoma sppEchinostoma spp

Heterophyes heterophyesHeterophyes heterophyes

lunglungParagonimus westermaniParagonimus westermani

Infective stage Forked tail cercaria

Diagnostic stage

Egg with lateral spine

Biomephlaria intermeddiat host

Schistosoma mansoni • Is caused by persons passing faces containing eggs of parasite into water which is used for bathing ,washing clothes ,fishing ….

• After mating ,mature S. mansoni flukes migrate to small tributary veins of inferior mesenteric, Which

drain large intestine. flukes can also be found in portal venous system.

Life cycle•Person become infected by

contact with water containing infective cercaria . Cercaria attached to skin and are able to penetrate unbroken skin (can penetrate mucous membranes).

•During penetration cercaria loss their tail and develop into schistosomules which migrate through SC tissue into blood vessels.

•In blood young flukes are carried through right side of heart to lung

•From lung most of schistosomules pass through left side of heart ,enter abdominal aorta, and from there reach the portal (liver ) circulation.

•In blood vessels of the liver ,young flukes reach maturity.

schisto in m. vein.jpg

..

CLINICAL FEATURESCLINICAL FEATURES : :

• Swimmer's itch: may occur at site of Swimmer's itch: may occur at site of cercarial penetration.cercarial penetration.

• In Schistosomiasis it is the eggs not In Schistosomiasis it is the eggs not adult which responsible for pathology.adult which responsible for pathology.

• Eggs acquiring host antigens and Eggs acquiring host antigens and protected from attack by host immune protected from attack by host immune responses.responses.

• Most eggs penetrate intestinal wall Most eggs penetrate intestinal wall and excreted in stool with blood and and excreted in stool with blood and mucus mucus

•Trapped egg mature Trapped egg mature normally normally secreting antigenssecreting antigens that produce strong immune that produce strong immune response.response.

•Egg it self do not damage Egg it self do not damage body,body,

cellular infiltrationcellular infiltration resultant resultant from immune response that from immune response that cause pathology associated cause pathology associated with schistosomiasiswith schistosomiasis

• Eggs lodged in mucosa lead to formation Eggs lodged in mucosa lead to formation of granuloma- ulceration and thickening of granuloma- ulceration and thickening of bowel of bowel

• large granuloma lead to colonic and large granuloma lead to colonic and rectal rectal polyp.polyp.

• Eggs reach liver through portal vein Eggs reach liver through portal vein causing thickening of portal vessels causing thickening of portal vessels ==periportal fibrosisperiportal fibrosis –in heavy infection –in heavy infection lead to enlarged liver with fibrosis-portal lead to enlarged liver with fibrosis-portal hypertension –ascites and splenomegaly.hypertension –ascites and splenomegaly.

• Varicose v. in oesophagus –hematemesisVaricose v. in oesophagus –hematemesis

• Eggs in spinal cord ,lung …..Eggs in spinal cord ,lung …..

pathology & clinical picture of Schistosoma mansoni 1-per patent period. 2-egg deposition and extrusion. 3-tissue proliferation.

1-prepatent period: a-skin penetration: causing skin irritation N.B. from cercarial skin penetration to passage of eggs (adult stage) it take 5-7 weeks.

b- systemic symptoms (slight fever, muscle pain,--)

2-Egg deposition and extrusion: Affect mainly large intestinal wall, liver and spleen. Intestinal wall: schistosomal dysentery (blood and mucus exudates in stool) ,thickening and fibrosis of colon and rectum. Hepatomegaly: due to egg deposition. Splenomegaly: due to congestion Egg deposition: in other organs e.g. kidneys and spinal cord.

3-Tissue proliferation & repair: Intestine:

fibrosis, thickening and development of papillomata, loss of tone , fibrous

constriction diarrhea fistulae. Periportal fibrosis ,esophageal varices

haematemesis ,ascitis . Pulmonary complications:

bronchopulmonary and cardiopulmonary (obstructive vascular disease ) cor pulmonale. CNS involvement.

Schistosoma hematobium

PathologyPathology::• Swimmer's itchSwimmer's itch

• Hematouria–eggs penetrate wall of Hematouria–eggs penetrate wall of

bladder (bladder (blood in urineblood in urine).).

• Eggs trapped in wall of bladder Eggs trapped in wall of bladder causing causing

granulomagranuloma..

• Many eggs calcified (sandy patch)Many eggs calcified (sandy patch)

• Urinary infection–kidney damage – Urinary infection–kidney damage –

squamous cell carcinoma.squamous cell carcinoma.

• Stones , nephrotic syndrome.Stones , nephrotic syndrome.

pathology& clinical picture of Schistosoma hematobium

1. Pre-patent period. 2. egg deposition and extrusion. 3. tissue proliferation.

1-Prepatent period a.Skin penetrations : cause skin irritation N.B. From cercarial penetration to passage of eggs (adult stage) it take 10- 12 weeks. b.Systemic symptoms (slight fever, muscle pain…)

2-Egg deposition and extrusion

Most eggs traped in sucbmucosa and muscularis of bladder. Initially painless terminal haematuria for months to years, then burning micturition.

Cystoscopy shows hyperplasia and inflammation of lower bladder, initial papillomata.

3 -Tissue proliferation& repair: a- Generalized hyperplasia and

fibrosis of bladder, lower ureter, sandy patches, squamous cell carcinoma. b- Calaculi: obstructive uropathy leading to: -retrograde infection. -hydronephrosis and renal failure.

c- periportal fibrosis (eggs from v. of rectum and colon… portal vein …liver (PPF)

d- lung involvement (eggs from hypogastric vein to- common iliac vein to –heart to lung )

Diagnosis of schistosomiasisDiagnosis of schistosomiasis::

• Is by finding eggs depending on Is by finding eggs depending on species in urine ,feces, or rectal species in urine ,feces, or rectal scrapingscraping..

Parasitological diagnosisParasitological diagnosis : :

• Urinary schistosomiasisUrinary schistosomiasis1.1. urineurine : sedmentation, : sedmentation,

centrifugation,and filtrationcentrifugation,and filtration

2.2. AspirateAspirate :: bladder cystoscopy.bladder cystoscopy.

3.3. BiopsyBiopsy : rectum protoscopy : rectum protoscopy

• Intestinal schistosomiasisIntestinal schistosomiasis::

Stool examination Stool examination

1.1. Direct smearDirect smear

2.2. Thick smear (kato method)Thick smear (kato method)

3.3. Concentration methodsConcentration methods..

Rectal mucosa :Rectal mucosa :

swab, aspirate and biopsyswab, aspirate and biopsy..

Ancillary investigation inAncillary investigation in

schistosomiasis:schistosomiasis:• EndoscopyEndoscopy:: papillomta papillomta• RadiologicalRadiological - Ultrasound for liver periportal - Ultrasound for liver periportal

fibrosis.fibrosis. - X-ray - X-ray calcification ,obstructive uropathycalcification ,obstructive uropathy Pulmonary changes e.g. cor Pulmonary changes e.g. cor

pulmonalepulmonale• Serological tests:Serological tests: ELISA mainly survey method to detect:ELISA mainly survey method to detect: Ab :light or old infection Ab :light or old infection Ag :in active infection.Ag :in active infection.

Chemotherapy of Chemotherapy of schistosomiasisschistosomiasis

praziquantel.praziquantel.

Fasciola hepatica

• Large fluke, 3x1.5cm• Causing fascioliasis• Common parasites of herbivores, cosmopolitan, mostly in sheep

raising areas.

Immature egg

•_Fasciola-hepatica-_Fasciola-hepatica-EggEgg

Life cycle of Fasciola heptica

Life cycle Adult egg (in water) miracidium (pierce snail soft tissue multiply give sporocyst rediacercaria metacercaria (infective stage on water plant), Upon ingestion metacercaria burrows through duodenal wall liver parenchyma bile duct where it becomes adult.

Pathology Invasion of adult to biliary tree producing biliary obstruction and fibrosis. Eating raw liver infected with Faciola, adult worm attaches to pharyngeal mucosa causing pain, bleeding and edema.

Diagnosis Eggs in duodenal aspirate and stools. (Exclude spurious infection.) Treatment : Bithionol Control: Avoid ingestion of infected plants.

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