Investigation of Leishmania infection and blood sources analysis in Phlebotomus chinensis (Diptera: Psychodidae) along extension region of the Loess Plateau, China

Abstract

BackgroundVisceral leishmaniasis (VL) was one of the most important parasitic diseases in China, caused by Leishmania protozoans and transmitted by sandflies. Recently VL cases have reappeared in China, including the extension region of the Loess Plateau. The purpose of this study was to detect the infection rate of Leishmania and analyze the blood sources of the sandflies vectors to guide the development of prevention and control measures. MethodsSandflies were collected by light traps from rural areas in Shanxian, Henan, China in 2015, as well as in Wuxiang and Yangquan, Shanxi, China in 2017. The blood sources of sandflies were analyzed by PCR detecting the host-specific mitochondrial cytochrome b (mtDNA Cyt b) gene fragments. Leishmania infection in sandflies was detected by amplifying and sequencing ribosomal DNA internal transcribed spacer 1 (ITS1). The Leishmania specific antibodies in the sera of local dogs were detected by ELISA. ResultsBlood sources showed diversity in the extension region of the Loess Plateau, including human, chicken, dog, cattle, pig and goat. Multiple blood sources within a sandfly individual were observed in samples from Yangquan (17/118, 14.4%) and Wuxiang (12/108, 11.1%). Leishmania DNA was detected in sandflies collected from Yangquan, of which 8.5% pooled and 1.9% individual samples were positive. The ITS1 sequences were conserved with the Leishmania donovani complex. The positive rate of Leishmania specific antibodies in dogs was 5.97%. ConclusionThis study detected the blood sources and Leishmania parasites infection of sandflies by molecular methods in the extension region of Loess Plateau, China. A high epidemic risk of leishmaniasis is currently indicated by the results as the infection of Leishmania in sandflies, the extensive blood sources of sandflies including humans, and positive antibody of Leishmania in local dog sera. Given the recent increase of VL cases, asymptomatic patients, dogs and other potential infected animals should be screened and treated. Furthermore, the density of sandflies needs to be controlled and personal protection should be strengthened.