Conference Abstract | Volume 8, Abstract ELIC2025114 (Poster 026) | Published: 30 Jul 2025
Paul Waliaula Wekunda1,2,3, &, Oladipo Ogunbode1, Oyeladun Okunromade1
1Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria, 2African Centre for Disease Control, Addis Ababa, Ethiopia, 3Department of Health, Vihiga County Government, Vihiga, Kenya
&Corresponding author: Paul Waliaula Wekunda, Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria, Email: wekundapaul@gmail.com
Received: 11 Apr 2025, Accepted: 09 Jul 2025, Published: 30 Jul 2025
Domain: Infectious Disease Epidemiology, Outbreak Investigation
Keywords: Lassa fever, Outbreak, Rodents, Mortality
©Paul Waliaula Wekunda 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: Paul Waliaula Wekunda et al., Epidemiological and environmental investigation of the January 2025 Lassa fever outbreak in Edo State, Nigeria. Journal of Interventional Epidemiology and Public Health. 2025;8(ConfProc5):00170. https://doi.org/10.37432/JIEPH-CONFPRO5-00170
Lassa fever (LF) is a viral hemorrhagic disease with a case fatality ratio exceeding 15% among hospitalized patients and potential for cross-border spread. We investigated the 2025 LF outbreak in Edo State to characterize its epidemiological pattern, assess factors contributing to mortality, and identify environmental conditions associated with rodent access and sources of infection.
We conducted a cross-sectional study using mixed methods. Cases were line-listed based on the standard case definition and managed at Irrua Specialist Teaching Hospital. Data was extracted from the line-list and clinical records. Environmental assessments were conducted in the homes of seven discharged patients using checklists and interviews. Quantitative data were analyzed descriptively, while qualitative data were categorized thematically.
By epidemiological week (epi-week) 7, 654 suspected and 77 confirmed LF cases were recorded, with 11 deaths (CFR, 14%). The median age of the confirmed cases was 29 years (IQR, 15-43), and 40 (52%) were male. Common symptoms included body weakness (86%), fever (83%), and abdominal pain (70%). Case counts, mortality, and positivity rate peaked in epi-week 2, at 28, 4, and 28%, respectively, before declining by epi-week 7. Three Local government areas, Etsako West, Esan Northeast, and Esan West, accounted for 65 (84%) confirmed cases and all reported deaths. Four of five patients (80%) with hemorrhagic symptoms died. Additional deaths resulted from neurological (2), liver (1), and kidney (1) complications. Rodent access and infestation were likely due to cracked walls, roof-to-wall gaps, bushy surroundings, and inadequate waste disposal sites. Potential sources of infection included open food and water storage practices.
This investigation underscores the population’s vulnerability to LF and its associated mortality, hence the need to strengthen surveillance and risk communication. Efforts to reduce transmission should focus on improving environmental sanitation, enhancing rodent control, and promoting safe food and water storage practices.
Menu