11.03.06 L Patel schistosomiasis

11.03.06 L Patel - Follow-up Follow-up Concern for malignancy to OR for right hemicolectomy hemicolectomy Extensive mucosal ulceration with

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Unformatted text preview: Follow-up: Follow-up: Concern for malignancy to OR for right hemicolectomy hemicolectomy Extensive mucosal ulceration with fibropurulent Extensive debris and underlying fibrosis debris Numerous calcified oval structures consistent Numerous with schistosomal eggs with No dysplasia or carcinoma identified 15 Lymph nodes with no malignancy Treated with praziquantel No further symptoms and H/H stable Schistosomiasis: The Migrating Trematode The Laura Patel November 3, 2006 Definition: Definition: Schistosomiasis or bilharzia Blood-dwelling fluke worm of the genus Blood-dwelling Schistosoma. 3 main species: main S. Haematobium S. Mansoni S. Japonicum Epidemiology: Epidemiology: >200 million infected worldwide >200,000 deaths annually On global scale, 1 in 30 people infected S. Mansoni- Subsaharan Africa, Middle East, S. South America, Carribean South S. Haematobium- North Africa, Subsaharan S. Africa, Middle East, India Africa, S. Japonicum- China, Phillipines, Thailand, S. Indonesia Indonesia S. Hematobium – Africa, Middle East S. Mansoni – Africa, Arabia, S. America, Caribbean S. Japonicum – Japan, China, Philippines S. Intercalatum – Rainforest belt of Africa S. Mekongi – Laos and Cambodia Infection acquired in childhood in Infection endemic areas endemic Peaks at age 15-20 Intensity of infection decreases with age Transmission higher in rural areas Higher risk near lakes and rivers. Life Cycle: Life Cercarial larvae penetrate skin migrate in the blood via lungs to liver become schistosomule mature over 4-6 weeks in the portal vein migrate to perivesical or mesenteric venules migrate female worm produces 100-3000 eggs/day female which migrate to lumen of bladder or intestine which Eggs excreted in urine or feces On contact with water, egg releases On miracidium (immature larvae) miracidium Miracidium finds the intermediate host, Miracidium freshwater snails. Multiply asexually into cercarial larvae Cercariae leave snail at 4-6 weeks and Cercariae spin in water for 72 h seeking a suitable host host Pathogenesis: Pathogenesis: Infection often asymptomatic Eggs can invade tissues, release toxins Eggs and enzymes immune response Inflammatory response, granulomas Worms absorb host proteins not attacked by host immune cells. Clinical Manifestations: Clinical Acute infection: More common in travelers Swimmer’s itch Katayama fever Chronic Infection: Endemic areas Higher burden of infection Katayama Fever 4-8 weeks after exposure Hypersensitivity reaction f/c, myalgias, arthalgias, dry cough, diarrhea, h/a Lymphadenopathy, HSM Peripheral eosinophilia Feces often negative for eggs Symptoms usually resolve after a few weeks Swimmer’s itch Often caused by animal and bird Often schistosomes but can be heralding sign of acute infection with human schistosome acute Local dermatitis Usually lower legs and feet Seen within 1 day of exposure Can last >1 week Often seen in people with repeat exposure Chronic infection: Chronic Intestinal Abd pain, diarrhea- bloody or nonbloody Secondary iron deficiency anemia Intestinal polyps Bowel ulcers and strictures Hepatic HSM secondary to portal HTN Deposition of collagen in periportal spaces Periportal pipestem fibrosis- Symmer’s fibrosis Ascites, varices Normal hepatocellular function Urinary May be asymptomatic Micro or macroscopic hematuria Dysuria, frequency Recurrent UTI Obstruction, hydroureter or hydronephrosis Proteinuria, nephrotic syndrome Increased risk of SCC of bladder Neuro Granulomas in spinal cord, brain Transverse myelitis Lower limb pain, weakness, bladder Lower dysfunction dysfunction epilepsy Pulmonary Seen more often if hepatosplenic disease present Presinusoidal portal HTN portosystemic collaterals Presinusoidal allows schistosomes into pulmonary circulation allows Eggs lodge in arterioles granulomas, endarteritis pulm HTN and cor pulmonale HTN Dyspnea CXR: fine miliary nodules Cardiac enlargement, dilated pulmonary arteries With initiation of treatmentWith embolization of worms to lungs cough, wheeze and new embolization infiltrates infiltrates Self limited Other manifestations: Other Recurrent BacteremiaRecurrent Enteric bacteria from inflamed colon Schistosomes may act as reservoir HIV Low CD4 counts may increase susceptibility of infection Low and influence egg excretion and Schistosomiasis may contribute to immune reconstitution Schistosomiasis syndrome after ARVT. Treating schistosomiasis can result in lower viral loads and Treating higher CD4 counts. higher Diagnosis: Diagnosis: Gold Standard: Microscopy of urine or stool S. Mansoni- prominent lateral spine S. Haematobium- terminal spine S. Japonicum- small, inconspicuous spine Nonspecific lab findings: Nonspecific Peripheral eosinophila Anemia Thrombocytopenia- if hepatosplenic Thrombocytopeniainvolvement involvement Mild elevation AP, GGT Hematuria Antibody assays: Look for antischistosomal Abs Does not distinguish current infection from Does past infection past Bad test in endemic areas Good for travelers Abs stay positive for up to 22 weeks after Abs treatment. treatment. Antigen detection: Can be used to assess cure Ag negative 5-10 days after treatment Used mostly for epidemiological and Used therapeutic studies therapeutic Development of fingerstick tests Treatment: Treatment: Praziquantel: MOA: induces changes in structure of worm tegument Increased permeability to calcium ions muscular contractions and paralysis and Exposes parasite Ag to immune response dislodgement of worms and expulsion by peristalsis worms Dose: 40 mg/kg in single dose OR 60mg/kg in 2 divided doses – in populations with high egg count. Side effects: h/a, nausea, abd pain, diarrhea Efficacy: Cures >85%, decreases Ag concentrations in >95% Test for cure: f/u stool cx >6 weeks post treatment. Prevention: Prevention: Safe water Sanitation, sewage control Eradication of snail species Education Mass chemotherapy Targeted at adolescents- yearly administration of Targeted praziquantel praziquantel Decreases transmission, decreases intensity of infection Difficult in low-income countries Concern for development of resistance Vaccine Development References: References: Gryseels B et al. Human Schistosomiasis. The Lancet Gryseels The 2006 Sept 23;368:1106-1118. 2006 UptoDate. Diagnosis and Treatment of UptoDate. Schistosomiasis. UptoDate. Epidemiology; Pathogenesis; and Clinical UptoDate. features of Schistosomiasis. features Zhong-Dao W, Zhi-Yue L, Xin-Ging Y. Development of Zhong-Dao a vaccine against Schistosoma japonicum in China: A Schistosoma Review. Acta Tropica 2005. 96: 16-116. Acta Ruth Walters, UNC pathology. ...
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This note was uploaded on 01/02/2012 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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