Nigeria reports 1,000 confirmed Lassa fever cases in the first 7 months of 2026

The Nigeria Centre for Disease Control and Prevention (NCDC) reported 1,000 confirmed Lassa fever cases from the beginning of the year through July 26, a 21 percent increase compared to the same period in 2025 (825).

In total for 2026, 23 States have recorded at least one confirmed case across 116 Local Government Areas.

Eighty-six percent (86%) of all confirmed Lassa fever cases were reported from 5 states (Ondo, Bauchi, Taraba, Edo and Benue) while fourteen percent (14%) were reported from 18 states with confirmed Lassa fever cases. Of the 86% confirmed cases, Ondo reported 32%, Bauchi 25%, Taraba 13%, Edo 10% and Benue 6%.

Concerning fatalities, 237 deaths among confirmed cases were reported. This is a 53 percent increase compared to the 155 deaths reported at this time in 2025.

The case fatality rate so far in 2026 is 23.7 percent.

Lassa fever (LF) is an acute viral illness and a viral haemorrhagic fever (VHF). The causative agent is a single-stranded RNA virus in the family Arenaviridae, the Lassa virus. This zoonotic disease is associated with high morbidity and mortality, and it has both economic and health security consequences.

The illness was first reported in Lassa community in Borno State, Nigeria, when two missionary nurses died from an unusual febrile illness. Since then cases and outbreaks continue to be reported in Nigeria and the diseases is increasingly recognised to be endemic in many parts of West Africa, including Nigeria, Benin, Ghana, Mali and the Mano River region (Sierra Leone, Liberia and Guinea), with the disease probably existing in other West African countries as well.

The Lassa virus is transmitted to man by infected multi-mammate rats, the mastomys natalensis species complex which is the reservoir host. Humans become infected from direct contact with the urine and faeces of the rat which contains the virus, through touching soiled objects, eating contaminated food, or exposure to open cuts or sores. Secondary transmission from person to person can occur following exposure to the virus in the blood, tissue, urine, faeces or other bodily secretions of an infected individual. Hospital-acquired (nosocomial) transmission from person to person are not uncommon, and importantly can occur if appropriate Personal Protective Equipment (PPE) is not worn when managing suspected cases.

Lassa fever presents with symptoms and signs similar to those of many febrile illnesses, thus making it difficult to diagnose clinically. The incubation period is between 6-21 days. It causes a syndrome characterised by fever, muscle aches, sore throat, nausea, vomiting, chest and abdominal pain. Although fever is not a constant presenting symptom, Lassa fever should be suspected in patients with fever not responding adequately to regular antimalarials and antibiotics. It should also be suspected in any outbreak setting with patients presenting with a compatible syndrome. It also likely has a wide spectrum of disease presentation, from relatively mild illness to severe haemorrhagic manifestations.