February 20, 2026

Lassa Fever: Outbreak, Symptoms, Prevention & Diagnosis

Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, first identified in Nigeria in 1969. It is endemic in West Africa, with Nigeria often recording the highest number of annual cases. Outbreaks occur most frequently between October and May, making the dry season a period of heightened risk.

The virus is primarily transmitted from infected rodents (Mastomys natalensis) to humans, and it continues to pose significant public health challenges due to environmental, social, and infrastructural factors. Poor waste management, overcrowded housing, and improper food storage significantly increase risk.

How Lassa Fever Spreads in Nigeria

1. Rodent-to-Human Transmission

The multimammate rat (Mastomys natalensis) serves as the natural reservoir for the virus. These rodents commonly inhabit and surround homes in many Nigerian communities. Humans become infected when they:

Touch food or household items contaminated with rodent urine or feaces
Inhale tiny particles from contaminated dust
Come into direct contact with rodents

Poor waste management, overcrowded housing, and improper food storage significantly increase risk.

2. Human-to-Human Transmission

Although less common, human-to-human transmission occurs through:

Contact with the blood, vomit, urine, saliva, or other bodily fluids of an infected person
Poor infection control in healthcare settings
Caregiving without protective equipment

Current Outbreak Trends

In 2025, Nigeria recorded over 955 confirmed cases and 176 deaths, and recent outbreaks in 2026 have affected multiple states, with hundreds of confirmed cases and a significant number of deaths. The states most frequently impacted include:

Edo
Ondo
Bauchi
Taraba
Ebonyi
Plateau

These patterns underscore the continued endemicity of the disease and the need for sustained preventive action.

Symptoms: What to Look Out For

Lassa fever has an incubation period of 2 to 21 days, and early symptoms often resemble malaria, making diagnosis challenging without laboratory testing.

Early Symptoms

Persistent fever
Weakness and tiredness
Headache
Sore throat
Muscle aches
Nausea or vomiting
Chest or abdominal pain

Severe Symptoms

If untreated, the disease may progress to more severe conditions, including:

Facial swelling
Difficulty breathing
Bleeding from the mouth, gums, or nose
Shock
Confusion
Seizures or coma

Most Vulnerable Groups

Pregnant women, especially in the third trimester
Children and the elderly
People with underlying health condition

Many survivors also develop temporary or permanent hearing loss

Preventive Measures: How to Stay Safe

Because there is no approved vaccine yet, prevention remains the most powerful tool against Lassa fever. Key protective measures include:

1. Rodent Control at Home

Store food in tightly covered, rodent-proof containers
Keep homes and surroundings clean
Dispose of garbage far from living areas
Seal holes and cracks that allow rodent entry
Avoid drying food in open spaces where rodents may contaminate it

2. Community and Personal Prevention

Store food in tightly covered, rodent-proof containers
Avoid contact with rodent droppings
Store grains properly to prevent rodent infestation
Educate family and community members on symptoms and risks

3. Healthcare Setting Precautions

Use appropriate personal protective equipment (PPE)
Implement strict infection prevention and control (IPC) measures
Immediately isolate suspected or confirmed cases
Handle laboratory samples safely

These practices protect both health workers and the broader community

Diagnosis and Management

Prompt diagnosis saves lives. Because early symptoms mimic malaria and typhoid fever, any fever that does not respond to malaria treatment should raise suspicion.

Diagnosis

Lassa fever is confirmed through laboratory tests, including:

PCR tests
Antigen detection tests
Antibody tests

Treatment

There is no universal cure, but early treatment significantly improves survival.

Supportive care is the cornerstone: rehydration, fever control, monitoring vital organs
Early presentation to a designated treatment center is critical

Why Early Care Matters

Most Lassa fever deaths occur due to late presentation, as many people initially treat symptoms as malaria at home. Early hospital care increases the chances of recovery and reduces complications.