The number of deaths from Lassa fever in Nigeria rose from 99 to 109 in just seven days, significantly higher than the number recorded during the same period in 2025.
The country has also continued to witness an increase in cases among health workers.
According to data obtained from the Nigeria Centre for Disease Control, at least 37 health workers have been infected in the first nine weeks of 2026, with six health workers affected in one week alone.
According to the NCDC data, at least 18 states in Nigeria have recorded at least one confirmed case of Lassa fever.
The NCDC also noted that, “86 per cent of all confirmed Lassa fever cases were reported from five states, which are Bauchi, Ondo, Taraba, Benue and Edo.”
It said, “Cumulatively as of week 9 of 2026, 109 deaths have been reported with a Case Fatality Rate of 23.2%, which is higher than the CFR for the same period in 2025 (18.7%).
“In total for 2026, 18 states have recorded at least one confirmed case across 69 local government areas.
“Eighty-six (86%) of all confirmed Lassa fever cases were reported from 5 states (Bauchi, Ondo, Taraba, Benue and Edo), while fourteen (14%) were reported from 13 states with confirmed Lassa fever cases.
“Of the 86% confirmed cases, Bauchi reported 28%, Ondo 22%, Taraba 19%, Benue 9% and Edo 8%.”
Furthermore, the agency noted that the predominant age group affected by the disease was 21-30 years, while the male-to-female ratio for confirmed cases was 1:0.8.
Also, “the number of suspected and confirmed cases decreased compared to that reported for the same period in 2025. Six new healthcare workers were affected in the reporting week 9.”
The NCDC further recommended that states bolster efforts year-round for community engagement on the prevention of Lassa fever, as it asked workers to maintain high suspicion for the disease.
On measures undertaken so far, the NCDC said it “held a national press briefing on the disease, disseminated updated IPC guidelines, [and] activated the incident management system for Lassa fever in Kebbi, Kano and Gombe states.
“Conducted high-level field missions to Bauchi State and held quality data meetings with high burden states.”
While listing some of its challenges, the NCDC blamed late presentation of cases, poor health-seeking behaviour by patients due to the high cost of treatment, and poor environmental sanitation conditions in high-burden areas.
Lassa fever is an animal-borne (zoonotic) acute viral illness spread by the common African rat, also known as the Mastomys rat species. It is endemic in Nigeria and several other West African countries.
Since the major outbreak of the disease in 2016, recurring cases have been on the rise.
According to the World Health Organisation, Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, a member of the arenavirus family.
Humans typically become infected through exposure to food or household items contaminated with the urine or faeces of infected Mastomys rats.
The disease remains endemic in rodent populations in parts of West Africa.
Lassa fever is known to be endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, Togo, and Nigeria, and it likely exists in other West African countries as well.
