The Nigeria Centre for Disease Control and Prevention has placed 1,277 individuals under observation for potential Lassa fever infection, following a rise in confirmed cases across the country.
Between January and March 30, 2025, the agency documented 659 confirmed infections out of 3,779 suspected cases, alongside 122 deaths.
According to a report released by the NCDC on Friday, Lassa fever has spread across at least 18 states, with Ondo, Bauchi, and Edo identified as the hardest hit.
The report reads in part: “Cumulatively, in week 13 of 2025, 122 deaths have been reported, with a Case Fatality Rate of 18.5%, which is lower than the CFR for the same period in 2024 (18.7%).”
The NCDC revealed that 93 Local Government Areas across the affected states have reported at least one confirmed case. The agency noted that the bulk of these infections, 71%, were traced to three states: Ondo, Bauchi, and Edo. The breakdown shows Ondo contributing 30%, Bauchi 25%, and Edo 16% of the total confirmed cases.
“In total for 2025, 18 states have recorded at least one confirmed case across 93 Local Government Areas. Seventy-one per cent of all confirmed Lassa fever cases were reported from these three states (Ondo, Bauchi, and Edo), while 29% were reported from 15 other states with confirmed Lassa fever cases. Of the 71% of confirmed cases, Ondo reported 30%, Bauchi 25%, and Edo 16%,” the report stated.
The data further showed that individuals aged 21 to 30 remain the most affected demographic, though cases span all age ranges from one to 94 years, with the median age standing at 30. A slight male predominance was also observed in the gender distribution of confirmed cases.
“The predominant age group affected is 21-30 years (Range: 1 to 94 years, Median Age: 30 years). The male-to-female ratio for confirmed cases is 1:0.8. The number of suspected cases increased compared to that reported for the same period in 2024. No new healthcare worker was affected in week 13. The National Lassa fever multi-partner, multi-sectoral Incident Management System (IMS) was activated to coordinate the response activities at all levels,” the report added.
So far in 2025, 20 healthcare workers across eight states have contracted the virus, which is transmitted primarily by contact with infected rodents — particularly the multimammate rat, the natural host of the virus. Other rodent species may also act as vectors.
As part of its containment efforts, the NCDC disclosed that while 1,277 contacts remain under follow-up, 1,448 have completed the surveillance process.
Lassa fever remains a year-round health concern in Nigeria, with heightened transmission typically occurring from October to May.
