Endemic Areas



Pathogenesis: pulmonary HTN due to anatomic obstruction by eggs/ intense granulomatous response to eggs
-Transmission: intermediate snail host release cercariae into fresh water: cercariae enter human through skin and transform into schistosomulae (which migrate through lungs and liver and develop into mature fluke in venous plexuses)
-Focus of infection: S. Mansoni reside in inferior mesenteric vein/ S. Japonicum reside in superior mesenteric plexus/ S. Haematobium reside in the vesical plexus
-S. Mansoni/ S. Japonicum: flukes release eggs into intestinal circulation, which lodge in portal veins (late in course, eggs travel via porto-systemic collaterals to pulmonary circulation)
-S. Haematobium: flukes release eggs into circulation, which lodge in urinary bladder
-Stool/ urine of infected persons transmits eggs back to soil, which hatch into miracidia (which invade the snail, intermediate host)


Acute worm migration:
-Katayama fever: transient pulmonary infiltrates/ leuko-cytosis (with eosinophilia)/ elevated immune complexes

Chronic infection:
-S. Mansoni/ S. Japonicum:
-Liver biopsy with characteristic pre-sinusoidal fibrosis (“Symmer’s pipestem fibrosis”): may aid in diagnosis of pulmonary HTN
-Hypoxemia (occurs late/ may occur early in cases with micro-scopic pulmonary A-V fistulae)
-PFT abnormalities: decreased DLCO/ obstruction/ decreased lung volumes
-CXR abnormalities: basilar or mid-zone infiltrates/ miliary infiltrates/ evidence of pulmonary HTN/ isolated granulomas (occasional)
-Stool O+P: demonstrates eggs (Kato thick smear: quantitative exam of stool)
-Urine O+P: eggs may be filtered out with a microfilter
-Rectal Bx: demonstrates eggs
-Sputum O+P: may rarely demonstrate eggs


Skin penetration:
-“Swimmer’s itch”: local transient dermatitis

Katayama fever (syndrome due to acute worm migration, probably due to reaction to invading schistosome rather than to eggs/ usually associated with heavy primary infection: mainly with S. Japonicum, rarely with S. Haematobium)
-Systemic: fever/ chills/ headache/ myalgias/ arthralgias
-GI: weight loss/ abdominal pain/ diarrhea/ hepatosplen-omegaly and lymphadenopathy (occur in 20-30% of cases)
-Pulmonary: dry cough/ wheezing
-Neurologic: transverse myelitis

Chronic infection:
-S. Mansoni/ S. Japonicum: fatigue/ intermittent diarrhea/ abdominal pain/ portal HTN (with relatively spared hepatic synthetic function)/ pulmonary HTN (dyspnea/ precordial chest pain)/ cyanosis, clubbing (may occur in cases with pulmonary A-V fistulae within granulomas or due to portopulmonary shunting)
-25% of patients with hepatic involvement have some evidence of pulmonary involvement (but <5% have Cor Pulmonale): hepatic involvement always precedes pulmonary involvement
-S. Haematobium: bladder and urinary tract involvement/ pulmonary HTN (may occur due to embolization of eggs via IVC)


-S. Mansoni/ S. Haematobium: 20 mg/kg BID X 1 day (alternate foro S. Haema-tobium: Metri-fonate/ alter-nate for S. Mansoni: Oxamiquine)
-S. Japonicum: 20 mg/kg TID X 1 day
-efficacy for treatment of Katayama fever is not known
-efficacy of treatment to re-verse hepatic/ pulmonary dis-ease in adults has not been shown (only proven in children)
-may precipitate an acute self-limited pulmonary reaction (due to released antigens from worms): cough/ wheezing/ eosinophilia/ new pulmonary infiltrates