Eosinophilia as a marker for chronic strongyloidiasis--use of a serum ELISA test to detect asymptomatic cases.

In a previously published survey of 602 former Far East prisoners of the 2nd World War (FEPOWs), 88 (15%) were found to have Strongyloides stercoralis infections. A further 25 (4.2%) had significant blood eosinophilia for no obvious parasitological or other medical cause. We have reinvestigated this latter group several years (range nine to 19 years) later, using a recently developed serum ELISA test as well as other standard parasitological procedures. Of the 11 who were still alive and traceable five (45%) were diagnosed as having strongyloidiasis. Eosinophilia in high risk groups such as former FEPOWs is very suggestive of Strongyloides infections. The serum ELISA test appears to be a useful, sensitive and specific screening test for this diagnostically difficult infection.