The development of an enzyme-linked immunosorbent assay for Trypanosoma vivax and its use in a seroepidemiological survey of the Eastern Caribbean Basin

Abstract

An enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against a South American (New World) strain of Trypanosoma vivax was developed and used for mass screening of cattle from 20 islands in the Eastern Caribbean Basin. The sensitivity and specificity of antigens prepared from a bovine-derived field strain and a murine-adapted laboratory strain of T. vivax, both of New World origin, were compared using an indirect fluorescent antibody (IFA) test, and an antigen prepared from the murine-adapted strain was subsequently used to develop an ELISA test. The results of the ELISA test were then compared with the results of a concurrently run IFA test. There was no cross-reactivity with either test using serum from a Trypanosoma theileri-infected cow. Both tests were weakly cross-reactive with sera from a T. brucei-infected steer, and the IFA test was moderately cross-reactive with several serum samples from a T. evansi-infected steer. For bovine sera collected from herds on islands in the Eastern Caribbean region, only five of 640 tested positive with the ELISA test. Thirty five of 653 sera tested were positive by IFA although the fluorescence elicited was weak as compared to that elicited by sera from known infected animals. Sera collected from 27 cattle in a region known to be free of T. vivax (OH U.S.A) were negative with the ELISA test, whereas seven of 30 sera from a herd in French Guiana known to be infected with T. vivax were positive. None of 45 caprine and 60 ovine sera collected from islands in the Eastern Caribbean region were positive by the IFA test, therefore an ELISA system for these species was not developed.