Understanding Lassa Fever: An Ongoing Health Challenge

Lassa fever is an acute viral hemorrhagic illness caused by the Lassa virus. It was first identified in 1969 in the town of Lassa, located in Borno State, Nigeria. Scientists discovered the virus after investigating cases of unexplained fever and bleeding in the region. Since then, Nigeria has faced repeated outbreaks, often occurring annually, with cases reported across many states and local government areas.

Historical Context of Lassa Fever

Since its discovery in 1969, Nigeria has recorded multiple outbreaks of Lassa fever. Notable spikes in cases occurred in 2018, 2019, 2020, 2022, and recent years. These outbreaks are typically seasonal, peaking in the dry season between November and May each year.

In 2018, Nigeria experienced one of the largest outbreaks on record, with confirmed cases across many states. The years 2022 and 2023 also saw significant numbers of confirmed cases and deaths.

Ongoing 2026 Outbreak

According to recent epidemiological data from Nigeria’s disease control agencies, the situation remains critical. In the first three weeks of 2026, Nigeria recorded 93 confirmed cases and 17 deaths, resulting in a case fatality rate (CFR) of about 18.1%. Confirmed cases were reported in multiple states, including Bauchi, Taraba, Plateau, Ondo, Edo, Ebonyi, Benue, and Nasarawa.

How Lassa Fever Spreads

Lassa virus is classified as a zoonotic disease, meaning it spreads from animals to humans. The natural reservoir host is the multimammate rat (Mastomys natalensis). Humans typically become infected through several routes:

• Contact with the urine or feces of infected rats, often via contaminated food, water, or household items.
• Inhalation of contaminated dust.
• Direct contact with infected bodily fluids.
• Person-to-person transmission can occur, especially in healthcare settings lacking adequate infection prevention and control practices.
  
  

Signs and Symptoms

The symptoms of Lassa fever can range from mild to severe. They usually appear 2–21 days after exposure. Approximately 80% of infections are mild or asymptomatic, but severe disease can occur.

Common symptoms include:

• Fever and general weakness
• Headache and malaise
• Sore throat, muscle, and chest pain
• Nausea, vomiting, and diarrhea
• Cough and abdominal pain
  
  

In severe cases, symptoms may escalate to:

• Facial swelling
• Fluid in lung cavities
• Bleeding from the mouth, nose, or gastrointestinal tract
• Low blood pressure, shock, tremors, seizures, disorientation, or coma in critical illness
• Pregnant women may experience high maternal and fetal mortality.
  
  

Among hospitalized patients, about 15% or more of severe cases may result in death.

Lassa Fever Prevention

Prevention Strategies

Currently, there is no licensed vaccine available to prevent Lassa fever. Several vaccine candidates are in development, but none are yet widely accessible. Therefore, prevention efforts focus on reducing the risk of infection through the following measures:

Reducing Rodent-to-Human Transmission

• Store food in rodent-proof containers.
• Maintain clean household environments.
• Dispose of rubbish far from homes.
• Avoid handling rats or their droppings.
• Keep rats out of homes and cooking areas.
  
  

Reducing Person-to-Person Transmission (For Caregivers)

• Follow strict infection prevention and control (IPC) measures in health settings.
• Use protective equipment when caring for sick individuals.
• Isolate suspected and confirmed cases promptly.
  
  

Community Actions

• Implement community hygiene and rat control and eradication campaigns.
• Raise public awareness to recognize early symptoms and seek care.
  
  

Early diagnosis and supportive care are crucial. Providing fluids can improve survival rates, and antiviral therapy, such as ribavirin, may be used in some cases.

Conclusion

Lassa fever remains a significant public health challenge in Nigeria. With ongoing outbreaks and the potential for severe illness, it is essential for communities to remain vigilant. By understanding how the virus spreads and implementing effective prevention strategies, we can work towards reducing the impact of this disease.

For more information on Lassa fever and its prevention, visit Lassa Fever Resources.