Lassa Fever

Lassa fever

Lassa fever is a very nasty viral haemorrhagic illness indeed. It’s caused by the Lassa virus, which is passed to humans via food and other objects contaminated by rat droppings.

It can also spread person to person, usually in labs and hospitals where there’s poor hygiene and infection control. And while it doesn’t spread in the air, it can spread sexually.

The fatality rate is 1% but severe cases come with a 15% risk of death, rising to 80% for pregnant women from six months onwards, with the same death risk for the unborn baby.

About Lassa fever and how to avoid it

Lassa is common in West Africa and endemic in Benin, Guinea, Liberia, Sierra Leone and some areas of Nigeria. Because it’s vital to get a diagnosis and the right medical help as soon as possible, it makes sense to find out about the symptoms before you travel to a country with a risk of Lassa.

Lassa fever symptoms

  • Symptoms develop in 6 – 21 days
  • The disease starts gradually with a fever and general weakness
  • A few days later patients start experiencing all or some of these: a headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, a cough and abdominal pain
  • Serious cases can involve a swollen face, fluid on the lungs, bleeding from the mouth, nose, vagina or stomach and intestines, plus low blood pressure and protein in the urine
  • Other serious symptoms include shock, seizures, confusion and a coma
  • 25% of those who survive go deaf, half of whom recover their hearing within 3 months
  • Some people temporarily lose their hair and others have a temporary abnormal gait
  • Worst case scenario: death within 14 days

Lassa fever diagnosis

Because the symptoms are so varied, it’s often a difficult diagnosis. The disease can look very like Ebola, malaria, shigellosis, typhoid fever and yellow fever.

The only real way to get an accurate diagnosis is via lab tests, and it’s important to remember that the lab test specimens themselves can be dangerous, needing careful handling. A lab will carry out these tests:

  • The antibody enzyme-linked immunosorbent assay (ELISA)
  • Tests to detect antigens
  • A reverse transcriptase polymerase chain reaction (RT-PCR) test
  • Isolating the virus in a cell culture

Who is most at risk?

Rural areas where the Mastomys rats that carry the virus live are the most risky, more so when the living conditions and sanitation are poor. This means health workers carry a particular risk, especially when caring for Lassa patients in a place where there’s insufficient barrier nursing control and sub-standard anti-infection.

Lassa fever treatment

The antiviral drug ribavirin works well as long as it’s given early enough. Other than that, doctors can only treat the symptoms. They do this by keeping oxygen and blood pressure under control, treating infections and complications, and maintaining balanced fluids and electrolytes.

How to avoid Lassa fever

  • Stop rats getting inside the building you’re staying in
  • Store food where rats can’t get to it, in rat proof containers
  • Keep everything really clean
  • Stay away from people who have any of the symptoms we’ve mentioned

Special advice for health workers

  • Avoid all contact with blood and body fluids
  • Apply extra-rigorous infection prevention and control whenever you are within a metre of patients: hand hygiene, respiratory hygiene and protective equipment
  • Use good injection practices
  • Leave sample taking and handling to trained experts
  • If a patient has Lassa fever, or you think they might have it, tell the authorities straight away

Advice for travellers

Luckily the countries where Lassa fever is a risk don’t tend to be holiday destinations. But if you need to travel to any of them, the most important way to protect yourself is scrupulous hygiene:

  • Keeping both yourself and your surroundings exceptionally clean
  • Taking great care around food and water
  • Steering clear of people who appear ill, bearing in mind the many and varied symptoms

If you’d like more advice, or simply want to talk through the risks with a professional, we’ll give all the support we can as well as providing all the essential travel vaccinations.