SCREENING FOR SCHISTOSOMIASIS, FILARIASIS, AND STRONGYLOIDIASIS AMONGEXPATRIATES RETURNING FROM THE TROPICS

The clinical utility of eosinophil determinations. stool examinations, and serological studies for detection of parasitic infection was exam ined in an asymptomatic expatriate population by retrospective chart r eview. The screened population consisted of 1,605 patients attending a tropical medicine clinic. The sensitivity of eosinophil counts as a s creening test for infection with filaria, schistosomes, or Strongyloid es stercoralis was 38%, and its positive predictive value was 9%. A co st-efficacy analysis of the use of three diagnostic tests in screening for infection with filaria (n = 23), schistosomes (n = 34), or Strong yloides (n = 7) was performed. The use of stool examination and serolo gical screening together had a sensitivity of 89%, at a total cost sim ilar to that of a conventional strategy involving a stool examination and an eosinophil count, which would have picked up only 61% of our ca ses. In this population, eosinophil counts contribute little to the di agnostic accuracy obtained with stool examination and serological scre ening, and the low specificity of eosinophil counts generates high cos ts.