The Nigeria Centre for Disease Control and Prevention (NCDC) has confirmed a total of 717 Lassa fever infections out of 4,881 suspected cases recorded between January 1 and May 4, 2025. The agency released this information in its latest weekly situation report published on Wednesday via its official website.

The infections were identified across 93 local government areas spanning 15 states, underscoring the continued spread of the deadly viral disease across multiple regions of the country.

Since the start of the year, 138 deaths have been attributed to the virus, translating to a case fatality rate (CFR) of 19.3%. This marks an increase from the 18.0% CFR recorded during the same period in 2024, highlighting a troubling trend in Lassa fever mortality despite ongoing interventions.

Slight Weekly Decline Offers Little Relief

During epidemiological week 18, which ended on May 4, the NCDC confirmed 10 new cases, a marginal drop from the 11 cases reported the previous week. However, this minor decline provides limited reassurance, as the virus remains active in multiple states.

The latest confirmed infections came from Ondo, Edo, Bauchi, and Benue states. Notably, 15 states have already recorded at least one confirmed case since January 2025, demonstrating the disease’s wide geographic spread.

Taraba Leads in Fatalities as National Death Toll Rises

The fatalities linked to Lassa fever are spread across 15 states, with Taraba State emerging as the worst hit, recording 34 deaths. This is followed by:

• Ondo State – 27 deaths

• Edo State – 19 deaths

• Bauchi State – 15 deaths

• Ebonyi State – 11 deaths

• Gombe State – 7 deaths

• Plateau State – 5 deaths

• Benue State – 5 deaths

• Kogi and Nasarawa States – 4 deaths each

• Delta and Kaduna States – 2 deaths each

• Enugu, Cross River, and Ogun States – 1 death each

These figures reflect the ongoing public health burden posed by Lassa fever, particularly in states already grappling with weak healthcare infrastructure and limited disease surveillance capacity.

Transmission Patterns and Demographics of Infection

Lassa fever, a viral hemorrhagic illness endemic to parts of West Africa, is primarily spread in Nigeria through contact with food or household items contaminated by the urine or feces of infected Mastomys rats.

According to the NCDC, 71% of all confirmed cases in 2025 have been concentrated in three states:

• Ondo State – 30%

• Bauchi State – 25%

• Taraba State – 16%

The remaining 28% of cases were distributed among the other 12 affected states.

The data also shows that the most affected age group falls between 21 and 30 years, with patient ages ranging from one to 96 years. The median age is 30, and there is a slight gender imbalance with more male patients, as reflected in a male-to-female ratio of 1:0.8.

Crucially, no new infections were reported among healthcare workers in week 18—a positive sign given the high risk these workers face during outbreaks.

Comparative Trends and Response Strategy

In its report, the NCDC observed that both suspected and confirmed cases have declined compared to figures from the same period in 2024. However, the increasing fatality rate has raised concerns over delays in diagnosis and treatment.

To strengthen its response, the NCDC has activated a multi-sectoral, multi-agency Lassa Fever Incident Management System (IMS), which coordinates activities at the national level. This system brings together government bodies, partner organizations, and relevant stakeholders to facilitate an integrated and rapid response.

Ongoing Challenges in the Fight Against Lassa Fever

Despite a coordinated national response, several challenges continue to hinder effective containment and treatment efforts. These include:

• Late presentation of patients at healthcare facilities, often when symptoms have advanced, reducing survival chances.

• High cost of treatment, which discourages many from seeking timely medical attention.

• Inadequate sanitation in high-burden areas, which increases exposure to rodent vectors.

• Low public awareness in affected regions, which delays symptom recognition and early intervention.

These issues remain persistent barriers to achieving sustained control of the disease, especially in rural areas where access to information and healthcare is limited.

Health Advisory: Public Urged to Remain Vigilant

The NCDC and other health authorities continue to urge Nigerians to adhere to preventive measures to curb further transmission. These recommendations include:

• Proper food storage to avoid contamination by rodents

• Maintaining clean environments to deter rodent infestation

• Avoiding contact with rats and their droppings

• Promptly seeking medical attention if symptoms such as fever, vomiting, and bleeding occur

Lassa fever is often misdiagnosed due to symptom overlap with other diseases such as malaria and typhoid, making awareness and early testing critical to saving lives.

Outlook: Sustained Vigilance Needed as Outbreak Persists

The current Lassa fever outbreak paints a mixed picture for Nigeria’s public health landscape. While the overall number of confirmed cases shows a gradual decline compared to the previous year, the rising death rate and widespread geographic footprint indicate that the virus remains a serious threat.

With the rainy season approaching—typically associated with a rise in rodent populations and subsequent Lassa virus transmission—public health officials warn that containment efforts must remain aggressive.

The NCDC, alongside state health ministries and global partners, is expected to ramp up its awareness campaigns, community-level surveillance, and diagnostic capacity in the coming weeks to prevent further escalation of the outbreak.