Evaluation of techniques for the diagnosis of Strongyloides stercoralis in human immunodeficiency virus (HIV) positive and HIV negative individuals in the city of Itajaí, Brazil

Abstract

Human immunodeficiency virus (HIV) and intestinal parasites are common in Brazil. Previous studies have shown that infection with Strongyloides stercoralis is frequently associated with HIV infection. Strongyloidiasis is difficult to diagnosis and stool examination with conventional techniques fails to detect the helminth larvae. We made a prospective study, to test the efficacy of the agar plate technique to detect S. stercoralis in 211 HIV-positive patients and 213 HIV-negative patients in the city of Itajaí, Brazil, between September 2001 and June 2002. The feces samples of these patients were processed and analyzed according to the following methods: Lutz, formalin ethyl acetate, Baermann, Harada-Mori and agar plate culture. HIV-positive patients were more frequently infected by S. stercoralis (odds ratio= 5,.687). Among the methods used on fecal specimens, the larvae of S. stercoralis were most efficiently detected by the agar plate (69.7%) method, followed by the Baermann and the formalin ethyl acetate methods (48.5%) (P=0.01), Lutz (42.4%) (P=0.01), and Harada-Mori culture (24%) (P=0.001). Therefore agar plate culture is the most efficient method for the detection of S. stercoralis larvae and this technique should be the test of choice, especially in immunocompromised patients.