Lassa Fever: Symptoms, Causes, Treatment and How to Prevent the Deadly Viral Disease
Learn everything you need to know about Lassa fever, including its causes, symptoms, treatment, transmission and proven prevention measures. Discover how to protect yourself and your family from this potentially deadly viral disease.
Lassa fever remains one of the most serious viral diseases affecting West Africa, particularly Nigeria, where seasonal outbreaks occur almost every year. Although many infected people experience mild or no symptoms, the disease can become life-threatening if not diagnosed and treated early.
Public health authorities, including the World Health Organisation (WHO) and the U.S. Centers for Disease Control and Prevention (CDC), continue to stress the importance of prevention, early detection and proper hygiene to reduce the spread of the disease. (World Health Organization)
What Is Lassa Fever?
Lassa fever is an acute viral hemorrhagic illness caused by the Lassa virus, a member of the arenavirus family. It was first identified in 1969 in the town of Lassa, in Borno State, Nigeria, where the disease got its name.
The disease is endemic in several West African countries, including Nigeria, Sierra Leone, Liberia, Guinea, Benin, Ghana, Mali and Togo. Health experts believe it may also be present in other neighbouring countries where surveillance is limited.
According to the WHO, the overall case-fatality rate is about 1%, but among patients hospitalised with severe illness, mortality can reach around 15%. Early diagnosis and supportive treatment significantly improve survival.
What Causes Lassa Fever?
Lassa fever is primarily spread by the multimammate rat (Mastomys natalensis), a rodent commonly found in many parts of West Africa.
People become infected when they eat food contaminated with rat urine or droppings, touch household items contaminated by infected rodents, inhale tiny particles contaminated with rodent waste, or prepare or consume infected rodents as food in some communities. (CDC)
The virus can also spread from person to person through direct contact with the blood, saliva, urine, vomit or other body fluids of an infected individual, especially in healthcare settings where proper infection-control measures are not followed.
Symptoms of Lassa Fever
Symptoms usually appear one to three weeks after infection.
About 80% of infected people experience mild or no symptoms, making the disease difficult to detect in its early stages.
Common early symptoms include fever, weakness, fatigue, headache, sore throat, and muscle pain.
As illness progresses, severe symptoms may include persistent vomiting, chest pain, abdominal pain, difficulty breathing, facial swelling, bleeding from the nose, mouth or gastrointestinal tract, shock, and organ failure.
One of the most common long-term complications is hearing loss, which may occur even in patients with mild disease. CDC estimates that about one-third of survivors experience varying degrees of deafness, some of which may be permanent.
Who Is Most at Risk?
Certain groups face a higher risk of severe illness, including healthcare workers exposed to infected patients, people living in rodent-infested environments, pregnant women, particularly during the third trimester, individuals with weakened immune systems, and family members caring for infected relatives without protective equipment.
Diagnosis and Treatment
Diagnosing Lassa fever can be challenging because its symptoms resemble those of malaria, typhoid fever and other viral illnesses.
Doctors rely on laboratory tests to confirm infection. Early diagnosis is critical because prompt treatment significantly improves survival.
There is currently no widely approved vaccine for Lassa fever.
Treatment mainly includes early administration of the antiviral drug ribavirin in appropriate clinical settings, intravenous fluids to prevent dehydration, oxygen therapies were necessary, blood pressure management, treatment of complications, and careful monitoring in hospital.
How to Prevent Lassa Fever
Since there is no licensed vaccine in widespread use, prevention focuses on avoiding contact with infected rodents and limiting person-to-person transmission.
1. Keep Rats Away from Your Home: Seal holes and cracks that rodents use to enter homes.
2. Store Food Properly: Keep grains, rice and other foods in tightly sealed, rodent-proof containers.
3. Maintain Good Hygiene: Dispose of refuse properly and keep homes, kitchens and surroundings clean to discourage rodents.
4. Avoid Contact with Rats: Do not handle or consume rodents that may carry the virus.
5. Wash Hands Regularly: Frequent handwashing with soap and clean water reduces the risk of infection.
6. Use Protective Equipment: Healthcare workers should wear gloves, masks, gowns and eye protection when caring for suspected or confirmed patients.
7. Isolate Infected Patients: Patients diagnosed with Lassa fever should be managed using appropriate infection-prevention and control measures to reduce transmission.
Why Lassa Fever Remains a Public Health Concern
Nigeria experiences seasonal outbreaks, particularly during the dry season, when human contact with infected rodents increases. Public health agencies have strengthened surveillance, laboratory testing and public awareness campaigns to improve early detection and response.
Experts warn that poor sanitation, rapid urbanisation and inadequate waste management continue to create environments where disease-carrying rodents thrive. Strengthening community hygiene, improving access to healthcare and educating the public remain essential to reducing infections.
Conclusion
Lassa fever is a preventable but potentially deadly disease that continues to pose a significant health challenge in West Africa. While most infections are mild, severe cases can lead to life-threatening complications and permanent hearing loss.
The best defence is prevention: maintaining clean surroundings, keeping rodents out of homes, storing food safely, practising good hand hygiene and seeking immediate medical attention if symptoms develop after possible exposure. With early diagnosis and prompt treatment, many lives can be saved.