Increased Prevalence of Lassa Fever Virus-Positive Rodents and Diversity of Infected Species Found during Human Lassa Fever Epidemics in Nigeria

Anise N. Happi, Testimony J. Olumade, Olusola A. Ogunsanya, Ayotunde E. Sijuwola, Seto C. Ogunleye, Judith U. Oguzie, Cecilia Nwofoke, Chinedu A. Ugwu, Samuel J. Okoro, Patricia I. Otuh, Louis N. Ngele, Oluwafemi O. Ojo, Ademola Adelabu, Roseline F. Adeleye, Nicholas E. Oyejide, Clinton S. Njaka, Jonathan L. Heeney, Christian T. Happi

Research output: Contribution to journalArticlepeer-review


The dynamics of Lassa virus (LASV) infections in rodent reservoirs and their endemic human caseloads remain poorly understood. During the endemic period, human infections are believed to be associated with the seasonal migration of Mastomys natalensis, thought to be the primary reservoir that triggers multiple spillovers of LASV to humans. It has become imperative to improve LASV diagnosis in rodents while updating their prevalence in two regions of Lassa fever endemicity in Nigeria. Rodents (total, 942) were trapped in Ondo (531) and Ebonyi (411) states between October 2018 and April 2020 for detection of LASV using various tissues. Overall, the LASV prevalence was 53.6%. The outbreak area sampled in Ondo had three and two times higher capture success and LASV prevalence, respectively, than Ebonyi State. This correlated with the higher number of annual cases of Lassa fever (LF) in Ondo State versus Ebonyi State. All rodent genera (Mastomys, Rattus, Crocidura, Mus, and Tatera) captured in both states showed slightly variable LASV positivity, with Rattus spp. being the most predominantly infected (77.3%) rodents in Ondo State versus Mastomys spp. (41.6%) in Ebonyi State. The tissues with the highest LASV positivity were the kidneys, spleen, and testes. The finding of a relatively high LASV prevalence in all of the rodent genera captured highlights the complex interspecies transmission dynamics of LASV infections in the reservoirs and their potential association with increased environmental contact, as well as the risk of zoonotic spillover in these communities, which have the highest prevalence of Lassa fever in Nigeria.

Original languageEnglish (US)
JournalMicrobiology Spectrum
Issue number4
StatePublished - Aug 2022
Externally publishedYes


  • infected tissues
  • Lassa diagnosis
  • Lassa fever
  • Lassa virus
  • Nigeria
  • small rodents

ASJC Scopus subject areas

  • Physiology
  • Ecology
  • General Immunology and Microbiology
  • Genetics
  • Microbiology (medical)
  • Cell Biology
  • Infectious Diseases


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