Small mammal diversity and dynamics within Nigeria, with emphasis on reservoirs of the lassa virus

<p>Nigeria has a rich small mammal community, with several species implicated as carriers of zoonotic microbes such as the Lassa virus (LASV). We sought to elucidate the diversity and distribution of these animals (including known LASV reservoirs) geographically, habitat-wise and seasonally. Our DNA-assisted survey detected at least 19 small mammal species amongst 790 specimens. Diversity indices were similar between ecological zones and also between endemic and non-endemic areas for Lassa fever. <i>Mastomys natalensis</i>, the most renowned LASV host, was present in eight out of nine localities sampled. We also described the spatial occurrence of other known LASV hosts such as <i>M. erythroleucus</i> and <i>Hylomyscus pamfi</i>, including carriers of LASV-like arenaviruses such as <i>Mus</i> (<i>Nannomys</i>) spp. The most numerous rodents (<i>Mastomys natalensis</i>, <i>M. erythroleucus</i>, and <i>Praomys daltoni</i>) were captured mainly inside human dwellings. Reproductive activity occurred throughout the year, but led to population peaks for <i>M. natalensis</i> in the dry season and for <i>M. erythroleucus</i> and <i>P. daltoni</i> in the rainy season. Extensive geographic distribution of LASV rodent reservoirs, with population peaks in different seasons, shows that the risk of rodent-to-human transmission of LASV is greater than currently realized.</p

Arenavirus Diversity and Phylogeography of Mastomys natalensis Rodents, Nigeria

Mastomys natalensis rodents are natural hosts for Lassa virus (LASV). Detection of LASV in 2 mitochondrial phylogroups of the rodent near the Niger and Benue Rivers in Nigeria underlines the potential for LASV emergence in fresh phylogroups of this rodent. A Mobala-like sequence was also detected in eastern Nigeria

New Hosts of The Lassa Virus.

Lassa virus (LASV) causes a deadly haemorrhagic fever in humans, killing several thousand people in West Africa annually. For 40 years, the Natal multimammate rat, Mastomys natalensis, has been assumed to be the sole host of LASV. We found evidence that LASV is also hosted by other rodent species: the African wood mouse Hylomyscus pamfi in Nigeria, and the Guinea multimammate mouse Mastomys erythroleucus in both Nigeria and Guinea. Virus strains from these animals were isolated in the BSL-4 laboratory and fully sequenced. Phylogenetic analyses of viral genes coding for glycoprotein, nucleoprotein, polymerase and matrix protein show that Lassa strains detected in M. erythroleucus belong to lineages III and IV. The strain from H. pamfi clusters close to lineage I (for S gene) and between II &III (for L gene). Discovery of new rodent hosts has implications for LASV evolution and its spread into new areas within West Africa