## 4 Discussion
Human illness due to LASV is currently reported in Guinea, Sierra Leone, Liberia and the Central African Republic. However, in Mali, a death due to LASV was reported in 2010 [28]. There are many asymptomatic forms and only 1% of cases are reported to be fatal. In Senegal, positive serologies have been found in _M. erythroleucus_, but no human cases are known [29]. The emergence of hantavirus hemorrhagic fevers in West Africa has been caused by the threat of _Crocidura theresae_ (_C. obscurior_) which was found to be infected by Tanganya virus (TGNV), the only shrew-associated hantavirus reported to date from sub-Saharan Africa [30]. Numerous positive serologies have also been reported throughout Senegal in domestic animals [31]. In Mauritania, cases of human Crimean-Congo hemorrhagic fever virus (CCHF) infection have been observed [32]. CCHV has already been isolated from bats in the Central African Republic [33]. Small rodents may participate in the epizoooty of CCHF [34]. Evidence of the passage of antiviral antibodies to this virus has been identified in rodents in Nigeria, Senegal, Ethiopia, Namibia, Madagascar and Egypt, and _R. rattus_ could be involved in the amplification of the virus. In addition, _M. natalensis_, _R. rattus_ and _C. olivieri_, abundant in both sites, were reported elsewhere with a potential role in the dissemination of Leptospira [35]. In Senegal, many species such as _R. rattus_, _Mastomys huberti_, _A. niloticus_ and _M. etrlroleucus_, identified as carriers of anti-Rift Valley fever (RVF) antibody, play a potential role as reservoirs of RVF virus. The role of rodents as a potential host within the natural cycle of RVF virus in the enzootic zone of Senegal is discussed; however, the highest antibody prevalence was recorded at Richard Toll (9.6%), within the enzootic area of the Senegal River delta [36]. The trapping yield was higher in Faladje (23.58%) than in Bougouni (13.48%), while the capture effort was greater and comparable to that obtained in three villages in Mali [36]. _M. erythroleucus_ and _M. natalensis_ were the most frequently captured species at both study sites, but the predominance of _M. erythrolocus_ observed in this sampling has also been reported in other localities in Senegal where it is endemic [9]. A study on Lassa fever in Mali [28] showed that the predominance of the genus _Mastomys_ spp. was 79.6%. _Arvicanthis ansorgei_ was not collected at either site, although this species had been reported in Mali [37]. The absence of _Arvicanthis niloticus_ and/or _A. ansorgei_ in our sample could be explained by the fact that the sampling was performed at night while this species has diurnal activity. _Rattus rattus_ was more abundant in Bougouni; _Rattus norvegicus_ was also found to be the predominant species in Algeria [38]. Bougouni is a inland city, which explains why _Rattus norvegicus_, often co-endemic with _R. rattus_ in African port cities, is absent there. The study of small mammalian species' reservoirs, geographic distribution and habitat associations help define potential disease endemic areas and more precisely identify the spatial variation in relative risk to humans.