Detection of schistosomiasis cases in low-transmission areas based on coprologic and serologic criteria The Venezuelan experience.

ABSTRACT

Low and very-low intensities of infection hinder the diagnosis of schistosomiasis. Therefore, new parameters should be established in order to more accurately identify active cases and true infection prevalence, for the adequate implementation of a control program. After the survey and analysis of the epidemiological characteristics of five Venezuelan communities, we propose three criteria for the definition of a "schistosomiasis case", based on different diagnostic methods: stool examination, ELISA-soluble egg antigen with sodium metaperiodate (SMP-ELISA), alkaline phosphatase immunoassay (APIA) and the circumoval precipitin test (COPT). Briefly, criterion I persons with Schistosoma mansoni eggs in stools; criterion II persons without eggs in stools, with positive COPT, without previous antischistosome chemotherapy in the last year; and criterion III persons without eggs in stools, with negative COPT, with two positive immunoenzymatic tests (SMP-ELISA and APIA), and with no previous chemotherapy. The incorporation of serological tests to epidemiologic surveillance in areas of low-transmission tries to compensate the underestimation of prevalence based only on parasitological diagnosis.