Nigeria Confirms Lassa Fever Case Fatality Rate of 18.5%

The Nigeria Centre for Disease Control and Prevention (NCDC) reported that since January 2025 and mid-September, a total of 7,673 suspected Lassa fever cases and 166 related fatalities have been reported.

Cumulatively, as at week #37, the Case Fatality Rate was 18.5%.

Ninety percent of confirmed cases are from the Nigerian states of Ondo, Bauchi, Edo, Taraba, and Ebonyi.

According to the NCDC, Lassa fever is an acute viral illness likely present in West African countries. The Lassa virus is primarily transmitted to humans via contact with food or household items contaminated with rodent urine or faeces. 

As of September 30, 2025, the U.S. CDC has issued Travel Health Notices for diphtheria, measles, and polio, but not Lassa Fever. While approved vaccines are available for the three diseases, there are no vaccines available for Lassa.

However, the International AIDS Vaccine Initiative has developed a Lassa fever vaccine candidate, which is currently being evaluated in a Phase IIa clinical trial in Ghana, Liberia, and Nigeria.