Case Study: Schistosomiasis Dr. Jennifer Coetzee CMID / Ampath

Clinical Presentation 8 year old boy Referred to renal clinic from peripheral hospital Two year history of painless, macroscopic hematuria Urine microscopy: eggs of Schistosoma haematobium

Objectives Describe the life cycle of the bilharzia parasite Discuss the pathogenesis of bilharzia as a prototype of a parasitic infection Briefly describe the principles of the diagnosis and management of this infection

Life Cycle of the Schistosome Life Cycle of the Bilharzia Parasite Ross A et al. N Engl J Med 2002;346:1212-1220

Pathophysiology and Clinical Disease Acute disease: Cercarial dermatitis after penetration of the cercaria “Swimmers itch” if cercaria from birds involved After onset of egg laying, may develop acute reaction (Katayama fever) if never exposed before Symptoms resolve as immune system adapts

Chronic Stages Eggs entrapped in host tissues secrete antigens Incite an inflammatory granulomatous response Granulomas eventually replaced by dense fibrosis obstruct blood flow Clinical symptoms vary according to species, total worm burden, patient’s stage of health at time of infection

Gastrointestinal Complications Wall of distal colon damaged as eggs pass through, become lodged Inflammatory response can cause focal ulcers or polyps May develop diarrhoea, abdominal pain or colitis ?Predisposing factor for colorectal carcinoma

Hepatosplenic Complications Eggs may incite granulomatous response in liver May become walled off with dense layers of fibrous tissue Pipestem fibrosis - obstructs portal veins Leads to portal hypertension, oesophageal varices, splenomegaly

Genitourinary Complications Eggs lodged in bladder wall - inflammatory infiltrate around the egg Overlying bladder epithelium hyperplastic, polyps Polyps erode, ulcerate - cause hematuria Log standing and severe infections may lead to carcinoma Fibrosis may lead to ureteric stricturing, hydronephrosis

Clinical Findings in Two Patients Infected with Schistosoma Species Figure 3. Clinical Findings in Two Patients Infected with Schistosoma Species. Panel A shows loose granuloma formation surrounding a Schistosoma haematobium egg (arrow) in a bladder-biopsy specimen from a 27-year-old man with hematuria and left-sided loin pain who had S. haematobium eggs in his urine (hematoxylin and eosin, x400). The black bar represents 100 {micro}m. In Panel B, a computed tomographic scan of the abdomen of the same patient shows gross bilateral hydronephrosis (arrows) due to ureteric stricturing. The right kidney is atrophic and nonfunctional. In Panel C, an ultrasonogram shows gross hepatic fibrosis (grade 3) (arrows) in a 45-year-old man with severe hepatic schistosomiasis. Ross A et al. N Engl J Med 2002;346:1212-1220

Other Complications Cardiopulmonary Complications: Eggs from shunted portosystemic blood lodged in pulmonary arterioles Granuloma formation, pulmonary hypertension, cor pulmonale Central nervous system: Eggs deposited in spinal column transverse myelitis-like syndrome

Laboratory Diagnosis Microscopy Detection of eggs in wet mounts of stool or urine S. manoni has a lateral spine, S. haematobium has a terminal spine Rectal or bladder biopsies may be necessary Also antigen and antibody detection Antibodies cross react with other helminth infections Problematic in endemic areas

An eight-year-old boy was referred to the nephrology clinic with a two-year history of painless, gross macroscopic hematuria Kaplan B and Meyers K. N Engl J Med 2000;343:1085

Management and Prevention Anti-schistosomal drugs Praziquantel Symptomatic management of complications Chemoprophylaxis available Vaccines under development Snail control!

Bibliography Ross A.G.P., Bartley P.B. et al. Schistosomiasis. New Eng J Med 2002; 346(16): 1212-1219 Coon D.R. Schistosomiasis: Overview of the history, biology, clinicopathology, and laboratory diagosis. Clin Micro Newsletter 27(21): 163-169