First Evidence of Lymphocytic Choriomeningitis Virus Infection in Humans in Africa by Detection of Neutralizing Antibody

Background: To date, case reports for human pathogenic arenavirus infections in the African continent have been limited to Lassa virus (LASV) in west Africa and Lujo virus in south Africa. Although the RNA genome of Lymphocytic choriomeningitis virus (LCMV) was also found in rodents, there is no report of the viral infection in humans. Here, we provide the first evidence of LCMV infection in humans in Africa. Methods: We tested a total of 141 plasma samples provided by healthy individuals in Gabon, central Africa, for detection of IgG antibodies to LCMV and LASV using ELISA. ELISA-positive samples were further examined by neutralization assay. Moreover, we investigated the viruses and the antibodies against them in rodents. Findings: The ELISA data showed that of the 141 samples, 47·5% and 6·4% were positive for IgG antibodies to LCMV and LASV, respectively. Statistical analysis suggested that the LCMV infection in females was higher. A neutralization assay confirmed IgG antibody specific to LCMV in one individual, which showed a remarkable reduction in infectivity to 6·2%. The antibody to LCMV was also found in Mus minutoides captured in the same area. These results uncovered the history of LCMV infection in humans in Africa. Interpretation: Gabon is exposed to LCMV infection transmitted by house mice such as Mus minutoides. LCMV infection should be considered a critical public health concern in Gabon and in Africa. Funding: Japan International Cooperation Agency (JICA), Japan Agency for Medical Research and Development (AMED), and Japan Society for the Promotion of Science (JSPS). Declaration of Interest: The authors declare no competing interests. Ethical Approval: The activities were performed under the research project “Establishment of a laboratory surveillance system for viral diseases of public health concern (SYMAV)” approved by the Institutional Review Boards of CERMEL and Nagasaki University (approval nos. CEI-007 and 170921177, respectively).