Serosurvey of canine leishmaniasis in five departments near an identified human clinical case in Marseille (France)

Leishmania infantum is a protozoan parasite of the family Trypanosomatidae, transmitted by the bite of phlebotomine sand flies (Diptera: Psychodidae). It is responsible for human and canine leishmaniasis in countries bordering the Mediterranean basin. Here we describe a clinical case of human cutaneous leishmaniasis in a 76-year-old female patient living in Marseille. Upon interrogation, the patient had no history of recent travel or contact with animals. The study involved clinical, serological, and molecular investigation of the occurrence of Leishmania infection in 718 dogs from five departments within a 130 km radius perimeter around Marseille. Five dogs showed signs of moderate leishmaniasis. Additionally, the serological survey of dogs revealed a global seroprevalence of 5.1%, with a significantly different prevalence in the Vaucluse department. Molecular analysis and phylogenetic studies highlighted the close relatedness of Leishmania strains between human and canine hosts with 99.6% of identity, indicating local transmission. The findings underscore the importance of serological surveillance in dogs and human. In a One Health approach, it is necessary to continue investigating Leishmania infection in all potential reservoirs, especially for zoonotic L. infantum in wildlife (red foxes, leporids, rodents, etc.) but also in dogs, cats, and equids.