Serological, parasitological and molecular tests for canine visceral leishmaniosis diagnosis in a longitudinal study.

Cáris Maroni Nunes,Cristiana De Melo Trinconi Tronco,Marcelo Nascimento Burattini,Valéria Marçal Félix De Lima,Maria Esther Gonçalves Pereira,Guilherme Dias De Melo,Marcia Dalastra Laurenti,Henrique Borges De Paula,Roberto Mitsuyoshi Hiramoto

doi:10.1590/s1984-29612015073

Abstract

One of the measures to control visceral leishmaniosis (VL) in Brazil is the identification and culling of the canine reservoir. There is much controversy concerning this strategy, including the proper identification of positive dogs and the fact that the host-parasite relationship changes over time make it more challenging. A dynamic cohort of 62 dogs was followed every three months using serological and parasitological examinations and PCR. Positivity by PCR was higher than by serology and by parasitological examinations and showed a tendency to decrease over time, while serology tended to increase after six months. Concomitant positivity in all tests was observed in 10.4% of the samples, and negativity in 29.1%. Overall sensitivity ranged from 43.6 to 64.1%, and was not uniform over time. The proportion of dogs with or without clinical signs was not different by cytology or PCR but PCR was able to identify a larger number of asymptomatic dogs compared to ELISA and immunochromatography. PCR can be useful for surveillance of areas where cases of canine VL have not yet been detected and in which control strategies can be implemented to limit the spread of the disease. Despite the advance in diagnostic tools CVL diagnosis remains a challenge.

Highlights

Visceral leishmaniosis (VL) is the most severe form of leishmaniosis, and the domestic dog is the main reservoir for Leishmania infantum (Syn. chagasi), which is transmitted to humans by the sandfly (DESJEUX, 2004)
Sixty-two dogs from an urban area that is endemic for visceral leishmaniosis (VL) were followed up, allowing us to observe variations in the canine visceral leishmaniosis (CVL) diagnosis according to the diagnostic method and disease progression over time
This is an essential difference to similar reports, in which the diagnostic comparison is usually made by cross-sectional studies, evaluating samples taken at only one time point (ASHFORD et al, 1995; SOLANO-GALLEGO et al, 2001; REITHINGER et al, 2002; MOREIRA et al, 2007; FALQUETO et al, 2009; GRIMALDI et al, 2012b; SILVA et al, 2013)

Summary

Introduction

Visceral leishmaniosis (VL) is the most severe form of leishmaniosis, and the domestic dog is the main reservoir for Leishmania infantum (Syn. chagasi), which is transmitted to humans by the sandfly (DESJEUX, 2004). One of the control strategies for VL in Brazil is the serological screening with subsequent culling of seropositive dogs (COSTA & VIEIRA, 2001; PALATNIK-DE-SOUSA et al, 2001; BRASIL, 2006). This approach has been the object of controversy due to the lack of scientific evidence in reducing the incidence of VL, the variability in the diagnostic techniques used and the long delay between a positive diagnosis and the elimination of the infected dog (COURTENAY et al, 2002; REITHINGER et al, 2002; COSTA, 2011; GRIMALDI et al, 2012a; OTRANTO & DANTAS-TORRES, 2013). In Brazil, the immunofluorescent-antibody test (IFAT) and the indirect enzyme-linked immunosorbent assay (ELISA) have been widely used for canine visceral leishmaniosis (CVL) mass‐screening surveys (GONTIJO & MELO, 2004; METTLER et al, 2005) until 2012, when a novel immunochromatographic assay (DualPath Platform – DPP®) was introduced for mass-screening (GRIMALDI et al, 2012b)

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