Conference Abstract | Volume 8, Abstract ELIC2025409 (Poster 030) | Published: 30 Jul 2025
Ephraim Ogbaini-Emovon1,&, Hanesh Chi2, Mambu Momoh3, Emmanuel Kerkula4, Rachael Omiunu1, Rita Esumeh1, Yemisi Ighodalo1, Oluwasola Babatunde1, John Sandi3, Fritz Fonkeng2, Berra Erkosar2, Sylvanus Okogbenin1, Cyril Erameh1, Mckenzie Colt4, David Wohl4,5, William Fischer II4,5, Ghyslain Mombo-Ngoma6,7, Michael Ramharter6,8,9, Nelson Adedosu10, Joseph Okoguale1, Goerge Akpede1, Mojeed Rafiu1, Reuben Eifediyi1, Chiedozie Ojide11, Stephan Guenther8, Daniel Bausch12,13, Aurelia Vessiere11, Donald Grant3, J. Sibley1, Devy Emperador14
1Irrua Specialist Teaching Hospital, Irrua, Nigeria, 2FIND, Geneva, Switzerland, 3Kenema Government Hospital, Kenema, Sierra Leone, 4UNC, Molecular Laboratory, Phebe Hospital, Phebe, Liberia, 5University of North Carolina, Chapel Hill, United States, 6Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon, 7Department of Implementation Research, Bernhard Nocht Institute for Tropical Medicine & I Dep of Medicine, University Medical Center Hamburg Eppendorf, Hamburg, Germany, 8Center for Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine and the Department of Medicine, University Medical Center Hamburg Eppendorf, Hamburg, Germany, 9German Center for Infection Research, Partner Site Hamburg-Lübeck-Borstel-Riems, Germany, 10Federal Medical Centre, Owo, Owo, Nigeria, 11Alex Ekweme University, Abakaliki, Nigeria, 12National University of Singapore, Singapore, 13London School of Hygiene and Tropical Medicine, United Kingdom, 14World Health Organization, Geneva, Switzerland
&Corresponding author: Ephraim Ogbaini-Emovon, Irrua Specialist Teaching Hospital, Irrua, Nigeria. Email: epogbaini@yahoo.com
Received: 05 Apr 2025, Accepted: 09 Jul 2025, Published: 30 Jul 2025
Domain: Infectious Disease Epidemiology
This is part of the Proceedings of the ECOWAS 2nd Lassa fever International Conference in Abidjan, September 8 – 11, 2025
Keywords: Lassa Fever, Immunoglobulin M, Serologic Tests, Sensitivity and Specificity
©Ephraim Ogbaini-Emovon et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Cite this article: Ephraim Ogbaini-Emovon et al., Evaluation of four Lassa virus IgM immunoassays for early detection and seroprevalence studies in West Africa. Journal of Interventional Epidemiology and Public Health. 2025;8(ConfProc5):00174. https://doi.org/10.37432/jieph-confpro5-00174
Immunoglobulin M (IgM) antibodies are the earliest serologic markers of acute Lassa virus (LASV) infection, making LASV-specific IgM assays essential for early diagnosis, particularly when combined with clinical suspicion. In clinical research, IgM assays may be used to assess immune responses to natural infection or vaccination. For reliable utility in such settings, assays should demonstrate high sensitivity (>90%) and specificity (>95%). However, performance data on available LASV IgM assays remain limited. This study evaluates the diagnostic performance of four commercial LASV IgM assays to determine their applicability in seroprevalence assessments and vaccine trials within Lassa-endemic regions.
This retrospective, multicenter diagnostic evaluation was conducted at three Lassa-endemic sites: Irrua Specialist Teaching Hospital (Nigeria), Kenema Government Hospital (Sierra Leone), and Phebe Hospital (Liberia). Four LASV-specific IgM immunoassays were assessed using archived frozen sera from RT-PCR-confirmed acute Lassa fever cases in Nigeria and Liberia, and LASV antigen-positive cases from Sierra Leone. All samples were collected within 12 weeks of diagnosis. LASV-negative sera were obtained from Gabon (non-endemic), and the U.S. CDC LASV IgM ELISA was used as the reference standard.
In pooled analysis, the ReLASV nucleoprotein (NP) assay demonstrated the highest sensitivity (95.3%, 95% CI: 81.0–99.0), while the BLACKBOX IgM assay showed the highest specificity (91.4%, 95% CI: 85.7–94.9). The ReLASV prefusion glycoprotein (pfGP) assay showed consistently poor sensitivity. Specificity varied by country, with reduced values observed in Sierra Leone. IgM sensitivity versus RT-PCR ranged from 18.5% to 62.3%, and specificity from 80.7% to 99.0%.
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