The Nigeria Centre for Disease Control and Prevention (NCDC) has confirmed that the Lassa fever death toll in 2025 has now risen to 177, based on its epidemiological report for Week 44 (ending November 2). This increase comes amid a worrying rise in the case fatality rate (CFR), which now stands at 18.3 percent, up from 16.5 percent during the same period in 2024.

The Scope of the Outbreak

As of Week 44, Nigeria has reported 966 confirmed cases of Lassa fever. The virus is now confirmed in 21 states, spanning 102 Local Government Areas (LGAs).

According to the NCDC, the burden of the outbreak is heavily concentrated: 87% of confirmed cases come from four states — Ondo, Bauchi, Edo, and Taraba.Specifically, Ondo accounts for 36% of all cases, Bauchi 21%, Edo 17%, and Taraba 13%.

Who Is Most Affected

The most affected age group is 21–30 years, with a median age of 30. The gender distribution shows a slight skew: male-to-female ratio is roughly 1:0.8 among confirmed cases.

Importantly, the NCDC noted that no new healthcare workers were infected in the most recent week, a hopeful sign for front-line safety.

Why the Fatality Rate Is Rising

Health experts suggest several possible explanations for the elevated CFR:

• Late presentation: Many patients don’t seek treatment early, which reduces their chances of recovery. Vanguard News+1
• Poor sanitation: The Lassa virus is carried by multimammate rats (Mastomys), and contaminated environments increase transmission risk. World Health Organization
• Cost of treatment: High costs and limited access to care discourage early health-seeking behaviour in many communities. Vanguard News

These factors, combined with seasonal dynamics (Lassa outbreaks tend to surge during the dry season), are contributing to the deadlier nature of this year’s outbreak.

What Is Lassa Fever?

Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, which belongs to the arenavirus family. Transmission to humans typically occurs through contact with items contaminated by rat droppings or urine. In addition, human-to-human transmission can occur, particularly in healthcare settings that lack strong infection control measures.

Public Health Response and Ongoing Challenges

The NCDC, working with a multi-sectoral technical working group, continues to coordinate response efforts across states. These include surveillance, public education, and rapid response teams.

Yet, the high fatality rate underscores the urgency of doing more:

• Enhancing community awareness about how Lassa is transmitted and how to prevent rodent infestations.
• Improving case detection and encouraging early health-seeking behaviour.
• Strengthening laboratory capacity and access to care in hotspot regions.
• Scaling up rodent control programs and improving environmental hygiene in high-risk LGAs.