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The small-mammal community of a typical Sudanian savannah area of south-eastern Senegal was studied by way of intensive sampling at the beginning (July) and at the end (November) of the rainy season. A total of 5931 trapnights and 200 pitfallnights yielded 767 small mammals, including 757 rodents of 12 species, as well as a few shrews and hedgehogs. Accumulation curve indicated that the rodent community was well sampled. Murine rodents were far more numerous than gerbilline rodents, and among them, Mastomys erythroleucus was the dominant species, being caught in high numbers in all habitats. Arvicanthis niloticus and Praomys daltoni were also abundant, followed by Mastomys natalensis and Gerbilliscus guineae. Abundances were high at the beginning of the rainy season when reproductive activity was low in all species. At the end of the rainy season, murine rodents were actively involved in reproduction, while gerbilline rodents were at their lowest density. Significant changes in relative abundance among habitats (including human dwellings) were observed between periods in some species, suggesting seasonal trends in habitat preferences. This may help species coexistence in this species-rich rodent community, in an area likely to be submitted to significant habitat alterations in the years to come. [ABSTRACT FROM AUTHOR]

Bioinvasion is a major public health issue because it can lead to the introduction of pathogens in new areas and favours the emergence of zoonotic diseases. Rodents are prominent invasive species, and act as reservoirs in many zoonotic infectious diseases. The aim of this study was to determine the link between the distribution and spread of two parasite taxa (Leishmania spp. and Trypanosoma lewisi) and the progressive invasion of Senegal by two commensal rodent species (the house mouse Mus musculus domesticus and the black rat Rattus rattus). M. m. domesticus and R. rattus have invaded the northern part and the central/southern part of the country, respectively. Native and invasive rodents were caught in villages and cities along the invasion gradients of both invaders, from coastal localities towards the interior of the land. Molecular diagnosis of the two trypanosomatid infections was performed using spleen specimens. In the north, neither M. m. domesticus nor the native species were carriers of these parasites. Conversely, in the south, 17.5% of R. rattus were infected by L. major and 27.8% by T. lewisi, while very few commensal native rodents were carriers. Prevalence pattern along invasion gradients, together with the knowledge on the geographical distribution of the parasites, suggested that the presence of the two parasites in R. rattus in Senegal is of different origins. Indeed, the invader R. rattus could have been locally infected by the native parasite L. major. Conversely, it could have introduced the exotic parasite T. lewisi in Senegal, the latter appearing to be poorly transmitted to native rodents. Altogether, these data show that R. rattus is a carrier of both parasites and could be responsible for the emergence of new foci of cutaneous leishmaniasis, or for the transmission of atypical human trypanosomiasis in Senegal., Competing Interests: The authors have declared that no competing interests exist.