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Impact of different Leishmania reservoirs on sand fly transmission: Perspectives from xenodiagnosis and other one health observations
Journal article   Peer reviewed

Impact of different Leishmania reservoirs on sand fly transmission: Perspectives from xenodiagnosis and other one health observations

Patrick Bourdeau, Edgar Rowton and Christine Petersen
Veterinary parasitology, Vol.287, pp.109237-109237
11/2020
DOI: 10.1016/j.vetpar.2020.109237
PMCID: PMC8035349
PMID: 33160145
url
https://www.ncbi.nlm.nih.gov/pmc/articles/8035349View
Open Access

Abstract

•Lectin receptor interactions dictate Leishmania/sand fly vector competence and transmission.•Historically each geographically defined area had one Leishmania vector and reservoir.•Molecular assays revealed that Leishmania/sand fly/reservoir ecology is much more complex.•Less traditional reservoirs are often underappreciated due to lack of experimental xenodiagnosis studies using these animals.•Each sand fly often feeds on multiple hosts in every region allowing multiple Leishmania reservoirs. Leishmania has biologically adapted to specific phlebotomine sand flies through long co-evolution. The ability of Leishmania spp. to bind to sand fly midgut allows each Leishmania species to propagate and differentiate into infectious promastigotes and be transmitted. Sand fly feeding upon a mammalian host is the first step towards being infected and a host of Leishmania. Once deposited into the skin, host susceptibility to infection vs. ability to mount a sterilizing immune response predicts which hosts could be reservoirs of different Leishmania spp. Materials, in addition to parasites, are expelled during sand fly during feeding, including salivary antigens and other factors that promote local inflammatory responses. These factors aid visceralization of infection increasing the likelihood that systemic infection is established. Any environmental factor that increases sand fly biting of a particular host increases that host’s role in Leishmania transmission. First descriptions of reservoir species were based on association with local human disease and ability to observe infected leukocytes on cytology. This approach was one pathogen for one reservoir host. Advances in sensitive molecular tools greatly increased the breadth of mammals found to host Leishmania infection. Visceralizing species of Leishmania, particularly L. infantum, are now known to have multiple mammalian hosts. L. donovani, long been described as an anthroponotic parasite, was recently identified through molecular and serologic surveys to have additional mammalian hosts. The epidemiological role of these animals as a source of parasites to additional hosts via vector transmission is not known. Current evidence suggests that dogs and other domestic animals either control infection or do not have sufficient skin parasitemia to be a source of L. donovani to P. argentipes. Further xenodiagnosis and characterization of skin parasitemia in these different hosts is required to more broadly understand which Leishmania spp. hosts can be a source of parasites to sand flies and which ones are dead-end hosts.
Leishmania Reservoir Sand fly Vector

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