Canine leishmaniasis in south-east of France: Screening of Leishmania infantum antibodies (western blotting, ELISA) and parasitaemia levels by PCR quantification

Leishmania infantum leishmaniasis is endemic in south-east of France. The main goal of our study was to evaluate the real prevalence of asymptomatic carriage in dogs by means of real time quantitative PCR (qPCR) and serology. We included prospectively 140 military dogs wearing deltamethrine-impregnated collars. Parasitaemia levels were then measured by means of quantitative real time PCR targeting kinetoplast DNA with TaqMan® chemistry. ELISA and western blotting (WB) were used for serological screening. The number of dogs working in three areas was the following: Var (n = 48), Bouches-du-Rhône (n = 61) and Corsica (n = 31). Prevalence of symptomatic dogs was 0.7% (n = 1). ELISA and WB were positive in one (0.71%) and 19 (14%) dogs, respectively. Fifty-eight dogs (41.4%) had a positive parasitaemia. Global prevalence (positive WB and/or positive qPCR) was 50% (n = 70). Mean parasitaemia was 0.018 parasites/mL in the global population and 0.043 parasites/mL in positive dogs [min: 0.0002 to max: 2]. The concordance percent for WB and qPCR results was 55% (n = 77). Regarding the prevalence of positive parasitaemia, a significant difference was noticed between dogs living in the Var region and those coming from the two other areas. Parasitaemia was rapidly positive within the first semester of stay in an enzootic area. Despite the use of deltamethrine-impregnated collars, the proportion of dogs with low parasitaemia is important. Thus, it may be relevant to evaluate the effect of screening and treating asymptomatic canine reservoirs on human infection by performing further studies comparing both populations.