The Nigeria Centre for Disease Control and Prevention (NCDC) has reported 1,119 confirmed cases of Lassa fever in 2025, with young adults emerging as the most affected age group across the country.

The update was shared in the NCDC’s Lassa Fever Situation Report for Epidemiological Week 51, covering the period from December 15 to 21, 2025. The report provides a detailed overview of the number of cases, deaths, and the states most impacted by the virus.

According to the NCDC, individuals aged 21 to 30 years accounted for the majority of confirmed infections, with the median age of affected patients recorded at 30 years. Males were slightly more affected than females, suggesting possible gender differences in exposure or healthcare-seeking behavior in regions with high transmission risks.

So far, 206 deaths have been reported among those diagnosed with Lassa fever, resulting in a case fatality rate of 18.4%. This is a slight increase from the 16.4% case fatality rate reported during the same period in 2024.

In Week 51 alone, 21 new confirmed cases and five deaths were recorded, showing a modest week-on-week decline from the previous week, which had reported 28 confirmed cases.

The states with confirmed cases during this period include Bauchi, Ondo, Taraba, Edo, Kogi, Ebonyi, and Plateau. In total, 21 states across 105 Local Government Areas (LGAs) reported at least one confirmed case of Lassa fever in 2025.

Four states—Ondo, Bauchi, Edo, and Taraba—were responsible for 88% of all confirmed infections, with Ondo contributing 35% of the total nationwide cases.

The NCDC identified several challenges in controlling the outbreak, including late presentation at healthcare facilities, poor health-seeking behavior due to the high costs of treatment, and inadequate sanitation in high-burden communities.

To address these issues, the agency urged healthcare workers to maintain a high index of suspicion for Lassa fever, ensure early diagnosis and treatment, and advised state authorities to strengthen risk communication and community engagement.

The NCDC also emphasized that it would continue to coordinate a multi-sectoral national response to the outbreak, focusing on surveillance, case management, laboratory support, and infection prevention and control in affected and at-risk communities.

Lassa fever is an acute viral hemorrhagic illness primarily transmitted through contact with food or household items contaminated with the urine or feces of infected rodents. Human-to-human transmission is also possible.