Potential animal reservoirs (dogs and bats) of human visceral leishmaniasis due to Leishmania infantum in French Guiana.

In French Guiana, cutaneous leishmaniasis is highly endemic, whereas no autochthonous case of visceral leishmaniasis have been reported so far. However, due to its proximity to Brazil which is highly endemic for visceral leishmaniasis, and the high transboundary population flow, an epidemiological challenge could arise at any time. As an overseas department and region and the largest outermost region of the European Union, epidemiological surveillance of visceral leishmaniasis is of great importance. Our study aimed to investigate the presence of Leishmania spp. in domestic (dogs) and sylvatic (bats) animals from French Guiana. Over the 2008-2018 period, samples from 349 animals were collected. They included blood from 179 autochthonous dogs and 59 bats, spleen samples from 33 bats and, blood from 78 military working dogs (MWD) collected before their departure from continental France and at the end of their four-month stay in French Guiana. Samples were screened using real-time polymerase chain reaction (qPCR) assays targeting Leishmania DNA followed by sequencing of 18S rRNA, kDNA and ITS2 genes. L. infantum was detected in 2.3% (8/349) of animals with 1.7% (3/179) of autochthonous dogs, 5.1% (4/78) of MWD returning from French Guiana, whereas they were negative before their departure. One of them dates back to 2012. All these dogs were positive for serological tests. In addition, L. infantum DNA was detectable in one bat spleen sample, belonging to Carollia perspicillata species. We report here for the first time an infection with L. infantum in dogs and bat from French Guiana. Our results suggest the existence of potential reservoir and transmission cycle for visceral leishmaniasis, at least since 2012, which was unknown in this territory until now. Further studies are needed to determine how these animals were infected and which vectors are involved in the transmission in this area. Author summary Leishmaniasis is endemic in French Guiana under its cutaneous form where Leishmania guyanensis is the principle parasite species. Visceral leishmaniasis is much more severe, although well known in neighbouring countries (Brazil, Suriname, Venezuela), it has not been known in French Guiana until now. Our study presents the result of a ten-year surveillance of Leishmania spp. infections in dogs and bats from French Guiana. We analyzed 92 bats from French Guiana 179 local dogs and 78 additional French military working dogs (MWD), which spent a short stay in this territory. Globally, we found 2.3% (8/343) of Leishmania infected animals. L. infantum infection was detected in 1.7% (3/179) of autochthonous dogs and 5.1% (4/78) of MWD. One of them dates back to 2012, the others were in 2016 and 2018. Low infection rate was detected in bats, only one specimen among 92 being infected (1.1%) and belonging to Carollia perspicillata species. We conclude that L. infantum has been circulating in French Guiana since at least 2012. Dogs and bats could therefore be among the potential reservoirs. Further investigations on potential additional reservoirs among domestic and wild animals, as well as identification of vectors, are required.