The flea Xenopsylla brasiliensis in Madagascar: updated distribution, host interactions, and initial assessment of insecticide susceptibility.

Xenopsylla brasiliensis is a plague flea vector in many countries around the world. Following its report in Madagascar, questions were raised about its bioecological features and its involvement in plague epidemiology. The objective of this study was to provide updated information on the bioecology, geographic distribution and susceptibility status of X. brasiliensis to insecticide. In this sense, fleas were collected in ten sites located in two districts of Sofia Region and geographic coordinates were recorded. Host-flea interactions were analyzed using bipartite package. Dead fleas were subjected to Yersinia pestis detection by PCR, whereas live fleas were exposed to 1% fenitrothion. In total, 2,434 individuals were collected among which 26.6% were Xenopsylla brasiliensis. Its abundance varied per site and it was recorded in eight among ten sites belonging to both districts. The flea was present in various ecological types at low to mid elevations (476 –1190 m). The majority of X. brasiliensis individuals (92%) were collected on black rats (Rattus rattus) but they could also infest the Asian house shrew (Suncus murinus) or the house mouse (Mus musculus). None among 42 flea samples was positive to plague bacillus and live fleas were susceptible to 1% fenitrothion. These findings represent the current knowledge on X. brasiliensis in Madagascar and will contribute to a better understanding of its roles in plague epidemiology.