Nigeria's Lassa Fever Outbreak Passes 1,000 Confirmed Cases as Deaths Climb to 237

Nigeria has recorded 1,000 confirmed cases of Lassa fever and 237 deaths so far this year, according to the Nigeria Centre for Disease Control and Prevention (NCDC).

The figures come from the agency's Lassa Fever Situation Report for epidemiological week 30, covering July 20 to 26, and mark one of the most severe years for the disease that Nigeria has faced.

Lassa fever is a viral illness spread mainly through contact with food or household items contaminated by the urine or droppings of an infected rat, most often the multimammate rat that is common across rural West Africa.

Person-to-person spread can also happen, particularly in hospitals and clinics where infection control is weak. The disease is endemic to Nigeria, meaning it circulates there every year, typically peaking during the dry season between December and May.

A toll that has already passed 2018's record

Nigeria's current outbreak has now exceeded the country's previous worst year for Lassa fever.

In 2018, a record-breaking epidemic pushed Nigeria's government and the World Health Organization to declare a public health emergency after 633 confirmed cases and 171 deaths were recorded across the full year.

This year's case count has already surpassed that entire total by the end of July, with five months still remaining in 2026.

The NCDC also reported that the case fatality rate, the share of confirmed patients who die, has risen to 23.7 percent this year, up from 18.8 percent over the same period in 2025.

That means close to one in every four people confirmed with the disease has died, a sharper toll than the same point last year.

Where the outbreak is concentrated

Confirmed cases have been reported in 23 states and 116 local government areas, but the outbreak remains heavily concentrated.

Five states, Ondo, Bauchi, Taraba, Edo and Benue, account for 86 percent of all confirmed cases nationwide. Ondo alone has recorded nearly a third of the country's cases, followed by Bauchi with a quarter. The remaining 14 percent of cases are spread across 18 other states.

Who is getting sick

Young adults are bearing the heaviest burden.

People aged 21 to 30 make up the largest share of confirmed cases, though patients have ranged in age from one to 93, with a median age of 30.

Slightly more men than women have been affected, at a ratio of roughly ten men to nine women.

Healthcare workers are among those infected

During the week under review, one healthcare worker was confirmed with Lassa fever, adding to a pattern of infections among frontline staff that has worried health officials throughout the outbreak.

In response, the NCDC says it has developed a 30-day Healthcare Worker Protection Plan, built with support from the World Health Organization and the United States Centers for Disease Control and Prevention, aimed at cutting infections among clinicians in the states hit hardest.

What is driving the deaths

The NCDC has pointed to several factors behind the rising fatality rate. Patients are often arriving at hospitals late in their illness, when treatment is less effective.

The agency also cited the high cost of treatment discouraging people from seeking care early, along with poor environmental sanitation and low awareness of the disease in high-burden communities.

In response, the NCDC says it has trained frontline health workers, pre-positioned protective equipment, expanded active case searches and contact tracing, and deployed National Rapid Response Teams to seven of the worst-affected states.

A disease West Africa knows well

Lassa fever is not unique to Nigeria.

The World Health Organization lists it as endemic in Benin, Ghana, Guinea, Liberia, Mali, Nigeria and Sierra Leone, and the Africa Centres for Disease Control and Prevention estimates that West Africa sees between 100,000 and 300,000 infections and around 5,000 deaths from the disease every year, though poor surveillance in some areas makes those figures approximate.

Nigeria has consistently reported the largest share of confirmed cases in the region in recent years, making its outbreak data a key indicator of how the disease is behaving across West Africa more broadly.

The NCDC has urged state governments to sustain community engagement on Lassa fever prevention throughout the year rather than only during outbreak season, and has called on healthcare workers to maintain a high index of suspicion for the disease and strictly follow infection prevention procedures.