Visceral leishmaniasis in an environmentally protected area in southeastern Brazil: Epidemiological and laboratory cross-sectional investigation of phlebotomine fauna, wild hosts and canine cases

Background Leishmaniasis is a rapidly expanding zoonosis that shows increasing urbanization. Concern exists regarding the role of wildlife in visceral leishmaniasis (VL) transmission, due to frequent natural or anthropogenic environmental changes that facilitate contact between wildlife, humans and their pets. The municipality of Campinas, in southeastern Brazil, initially recorded VL in 2009, when the first autochthonous case was confirmed in a dog living in an upscale residential condominium, located inside an environmentally protected area (EPA). Since then, disease transmission remains restricted to dogs inhabiting two geographically contiguous condominiums within the EPA. Methodology/Principal findings We conducted a cross-sectional study of the VL focus to investigate Leishmania spp. infection in domestic dogs, wild mammals and sand flies using molecular tools and recommended serological techniques. Canine seroprevalences of 1.5% and 1.2% were observed in 2013 and 2015, respectively. Six insect species, confirmed or suspected vectors or potential transmitters of Leishmania, were identified. Two specimens of the main L. (L.) infantum vector in Brazil, Lutzomyia longipalpis, were captured in the EPA. Natural infection by L. (L.) infantum was recorded in one Expapillata firmatoi specimen and two Pintomyia monticola. Natural infection by L. (L.) infantum and Leishmania subgenus Viannia was also detected in two white-eared opossums (Didelphis albiventris), a known reservoir of VL. Geographical coordinates of each sampling of infected animals were plotted on a map of the EPA, demonstrating proximity between these animals, human residences, including the dogs positive for VL, and forest areas. Conclusions/Significance The EPA, which is inhabited by humans, has an active VL focus. The risk of establishing and maintaining disease transmission foci in similar scenarios, i.e. wild areas that undergo environmental modifications, is evident. Moreover, different epidemiological profiles of VL must be included to elaborate prevention and control measures that consider the particularities of each transmission area.
Author summary Leishmaniasis are neglected tropical diseases that represent a major public health problem in the world. New outbreaks have been recorded in the outskirts of some cities and phlebotomine vectors show geographic expansion, potentially associated with environmental and climate changes. We investigated a recent focus of visceral leishmaniasis (VL) in dogs from two residential condominiums located in an environmentally protected area in the municipality of Campinas, São Paulo, southeastern Brazil. The purpose of the study was to investigate Leishmania (L.) infantum infection, the etiological agent of the disease, in vector insects (phlebotominae), domestic (dog) and wild hosts. Antibody prevalence was determined in 1.5% and 1.2% of dogs examined in 2013 and 2015, respectively. In addition, natural infection by the VL agent was confirmed in two species of sand flies and two white-eared opossums. All positive animals were captured near human residences and in forest areas. Scenarios like these, with changes in ecosystems and the proximity of wild and domestic animals and humans, can promote the occurrence of zoonoses. The participation of wildlife in the transmission cycle of zoonoses has assumed greater importance in recent years as a result of the consolidation of the One Health concept.