Chronic Strongyloides stercoralis infection in former British Far East prisoners of war

Background: Chronic infections with the nematode worm Strongyloides stercoralis can occur in former WWII Far East prisoners of war (FEPOWs). The condition may be asymptomatic, but frequently causes a characteristic urticarial 'larva currens' rash. Under conditions of immunosuppression (particularly systemic corticosteroid treatment) potentially fatal dissemination of larvae ('hyperinfection') may occur. Aim: To review our total experience of strongyloidiasis in former FEPOWs, and investigate its prevalence, characteristics and risk factors. Design: Retrospective case series. Methods: We reviewed 2072 records of all FEPOWs seen at the Liverpool School of Tropical Medicine, 1968-2002. Cases with strongyloidiasis were compared with non-infected controls. Results: There were 248 (12%) with strongyloidiasis. Diagnostic features included larva currens rash (70%), eosinophilia (66%), positive faecal culture (30%), positive faecal microscopy (26%), and positive serology (64%). Mean (+/-SD) age of cases was 65 7 years, and as expected, their blood eosinophil counts were significantly higher than controls (775 vs. 238 x 10(6)/1, p < 0.001). Captivity on the Thai-Burma Railway (vs. elsewhere) was significantly associated with strongyloidiasis (78% cases vs. 40% controls, OR 4.19, Cl 2.70-6.81, p<0.001). In terms of prevalence, strongyloidiasis occurred in 166/1032 men imprisoned on the Burma Railway (16.1%). Malaria (88% vs. 69%, p<0.001) and tropical ulcer (53% vs. 42%, p<0.02) were more common amongst cases than controls, probably because these diseases were very common on the Burma Railway. Discussion: S. stercoralis infection is common amongst ex-FEPOWs, particularly those from the Thai-Burma Railway project. It is usually characterized by a 'larva currens' rash and marked eosinophilia. The condition is eminently treatable, and continued diagnostic surveillance is needed, if cases of potentially fatal hyperinfection are to be avoided.