Press Release

WRAIR scientists and collaborators identify previously unreported animal reservoirs for Lassa virus in Nigeria

Silver Spring, Md. - In collaboration with the African Centre of Excellence for Genomics of Infectious Diseases (ACEGID) and HJFMRI, Walter Reed Army Institute of Research (WRAIR) completed a study demonstrating, for the first time, that non-rodents such as lizards, pigs, dogs, sheep, goats and cattle are reservoirs for Lassa virus (LASV) in southern Nigeria. These non-rodent reservoirs were in close contact with humans who tested positive for LASV infection, suggesting potential involvement during transmission. Findings were published last month in Emerging Microbes & Infections.

The study’s results demonstrate that LASV variants emanating from non-rodent animals may contribute to human infection rates by contributing to spillover events from animals to humans. Understanding how zoonotic LASV variants incubate, evolve, and spread can help scientists improve predictions for and responses to future Lassa fever outbreaks, as well as inform the development and evaluation of medical countermeasures to control LASV.

“The genomic characterization of LASV in non-rodents will provide a better insight into host-virus interactions, as well as the evolution and diversity of the virus,” said Dr.  Christian Happi,  ACEGID Director, Redeemer’s University, Nigeria. “These findings of LASV in previously unreported species among other hosts will allow for better predictions of future Lassa fever emergence.”

Lassa fever is endemic in most parts of Western Africa with thousands of LASV infections occurring in humans annually. Predicting who is more likely to be infected with LASV based on environmental, behavioral, and genetic factors can inform governments and multilateral health entities in developing best practices around lifestyle, conservation, disease prevention and vaccine development.

“WRAIR’s longstanding partnerships in Nigeria span decades and are critical to conducting infectious disease research to develop preventive and therapeutic countermeasures,” said Dr. Nelson Michael, Director of WRAIR’s Center for Infectious Disease Research. “This LASV epidemiology research is a part of ongoing efforts among partners to enhance biopreparedness against emerging infectious disease threats in the region and proactively develop tools in advance of future outbreaks.”


The Walter Reed Army Institute of Research ( is part of the US Army Medical Research and Development Command. WRAIR provides research capabilities and medical solutions to Force Health Protection and Readiness challenges facing US Service Members. These provisions include anticipating threats arising during future operations. WRAIR created a model of vaccine and therapeutic development that is unique, nimble, and responsive to dynamically evolving infectious disease threats of military importance. Leveraging WRAIR’s expertise, facilities, and international network, today the Institute helps develop many of the vaccines and drugs in use by military and civilian medicine worldwide. In 2018, the Emerging Infectious Diseases Branch was created with an explicit mission to survey, anticipate and counter the growing threat of emerging infectious diseases of key importance to US forces in the homeland and abroad.

 About this study

This work was funded primarily by WRAIR under a Cooperative Agreement with the Henry M. Jackson Foundation for the Advancement of Military Medicine (#W81XWH-18-2-0040). This work also received support from a cohort of donors through the TED’s Audacious Project, including the ELMA Foundation, MacKenzie Scott, and the Skoll Foundation. Additional support for this work was through grants from the National Institute of Allergy and Infectious Diseases (, NIH-H3Africa ( (award number U01HG007480, and U54HG007480 respectively), the World Bank grants project ACE-019 and ACE-IMPACT. Further support was received from the Rockefeller Foundation (Grant #2021 HTH), the Africa CDC through the African Society of Laboratory Medicine [ASLM] (Grant #INV018978), and the Science for Africa Foundation.