Study of cross-reactivity in serum samples from dogs positive for Leishmania sp., Babesia canis and Ehrlichia canis in enzyme-linked immunosorbent assay and indirect fluorescent antibody test

Trícia Maria F De Sousa Oliveira,Débora De Carvalho,Patrícia I Furuta,Rosangela Z Machado

doi:10.1590/s1984-29612008000100002

Abstract

To verify the presence of cross-reaction among leishmaniosis, ehrlichiosis and babesiosis in serological diagnostics used in human visceral leishmaniasis control programs, serum samples from leishmaniasis endemic and non-endemic areas were collected and tested by Indirect Fluorescent Antibody (IFAT) and Enzyme-linked immunosorbent assay (ELISA). All serum samples from endemic areas were positive for Leishmania sp., by ELISA and IFAT, 51% positive for Babesia canis and 43% for Ehrlichia canis by IFAT. None of the serum samples from non-endemic areas were positive for Leishmania sp., by IFAT, but 67% were positive for B. canis and 78% for E. canis using the same test. When tested by ELISA for Leishmania sp., four samples from non-endemic area were positive. These dogs were then located and no clinical signs, parasites or antibody was detected in new tests for a six month period. Only one of these 4 samples was positive for B. canis by IFAT and ELISA and three for E. canis by IFAT. The results of the work suggest a co-infection in the endemic area and no serological cross-reaction among these parasites by IFAT and ELISA.

Highlights

Visceral leishmaniasis is a very important zoonotic disease in South America, mainly in Brazil, where it is caused by Leishmania (Leishmania) chagasi and its vector is Lutzomyia longipalpis sand flies (ARIAS, 1996)
Serum samples: Positive Babesia canis reference sera (n=2) were obtained from dogs experimentally infected with B. canis vogeli (FURUTA, 2004) and E. canis reference sera (n=8) were obtained from dogs experimentally infected by E. canis (CASTRO et al, 2004)
Serological results obtained by the samples from Jaboticabal were expected, since the city is endemic for canine ehrlichiosis and babesiosis, but not for leishmaniasis (FURUTA, 2004; NAKAGHI et al, 2004)

Summary

Introduction

Visceral leishmaniasis is a very important zoonotic disease in South America, mainly in Brazil, where it is caused by Leishmania (Leishmania) chagasi and its vector is Lutzomyia longipalpis sand flies (ARIAS, 1996). Domestic dogs (Canis familiaris) are reservoir hosts of zoonotic visceral leishmaniasis, and control of canine leishmaniasis is imperative to reduce the amount of parasites available to sand flies, reducing the human incidence of the disease. Despite evidence from experimental studies showing a decreased incidence of visceral leishmaniasis in both dogs and children following serological screening of dogs and killing of sero-positive animals, the efficiency and acceptability of this control strategy is increasingly being debated. In Brazil, dog treatment is not recommended, since it can reduce clinical signs, but not the sand fly infection (BRASIL, 2006)

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Conclusion