Cross-reactivity in serological tests between Chagas disease and visceral leishmaniasis in endemic regions for both diseases

Abstract

In the Brazilian Amazon is not uncommon to find areas with intersecting occurrence of several tropical diseases, among these acute Chagas disease and visceral leishmaniasis (VL) are highlighted, particularly by changes in the epidemiology of these diseases in recent years. Clinical findings are also common in some cases and serological tests can present cross-reactivity between those diseases. The objective of this case report is to highlight the importance of careful clinical evaluation in order to obtain a correct interpretation of serological tests. A case with febrile syndrome with two months of evolution was presented, associated with wasting syndrome and hepatosplenomegaly, where the first diagnostic test for acute Chagas disease, using the indirect immunofluorescence method, was positive for IgM and IgG. It was obtained the same result with the hemagglutination test. Serological tests for VL was equally positive, with high titer IgG (1:2560). Other clinical findings such as hepatosplenomegaly and pancytopenia helped to elucidate the diagnosis of VL. The effective therapeutic response to the treatment with antimonial for VL was a final evidence for the diagnosis in this case. It is emphasized the necessity of a careful clinical evaluation for the proper interpretation of serological tests and also the development of more specific tests that is highlighted in a context of simultaneous occurrence of these health problems as occur in the Amazon region.