Bioecology of fleas with a focus on the plague vector Xenopsylla Brasiliensis in Mandritsara district, Northern Madagascar.

The rat flea Xenopsylla brasiliensis, a known plague vector present in East and South Africa, has recently been identified in Mandritsara, Madagascar, a plague-endemic area. However, its national distribution remains poorly documented, and studies on other flea vectors and their small mammal hosts in this district are limited. We surveyed flea species, their mammalian hosts, and flea abundance, with a particular focus on X. brasiliensis, in four sites of Mandritsara District between 2021 and 2022. Small mammals were trapped for three consecutive nights per site, inside and outside houses, off-host fleas were collected indoors. Three rodent species including Rattus rattus (black rat), Mus musculus (house mouse), and Suncus murinus (Asian house shrew) and six flea species were identified. The fleas included Xenopsylla cheopis, X. brasiliensis, Synopsyllus fonquerniei, Echidnophaga gallinacea, Ctenocephalides felis strongylus, and Tunga penetrans. Xenopsylla cheopis, X. brasiliensis, and S. fonquerniei were found on all three rodent species, predominantly infesting R. rattus. The black rat and X. brasiliensis were the most abundant species, accounting for 80.2% and 47.8% of the captured small mammals and fleas, respectively. This study reveals a high diversity of flea species associated with small mammals, extends the known geographical distribution of X. brasiliensis and confirms its lack of host specificity. Given the role of some of these fleas as zoonotic disease vectors, further research is recommended to assess pathogen transmission risks to humans.