Lassa fever in West Africa

Updated: April 09, 2018


Original publication date: August 21, 2017

What is Lassa fever?

Lassa fever is a viral haemorrhagic illness caused by the Lassa virus. Lassa virus is most commonly spread through the urine and feces of infected rats.

This includes:

Lassa virus may also be spread between humans through direct contact with the blood, tissue, urine, feces or other bodily fluids of a person infected with Lassa fever.

Symptoms of Lassa fever are usually gradual and include:

The disease can progress with symptoms of:

There is no vaccine or medication that protects against Lassa fever.

Where is Lassa fever a concern?

Lassa fever is a known risk in West Africa. It occurs in Benin, Burkina Faso, Ghana, Guinea, Liberia, Mali, Nigeria, Sierra Leone, Togo and other West African countries.

Nigeria is currently experiencing an outbreak of Lassa fever. Over 1 400 suspected cases and 115 deaths have been reported in 2018. Cases have been reported in 19 of 36 states. Cases related to this outbreak have been reported in Benin.

In 2017 and 2018, the World Health Organization has confirmed cases and/or outbreaks of Lassa fever in:

At greatest risk are those who:

How can you protect yourself from Lassa fever?

Consult a health care provider or visit a travel health clinic at least six weeks before you travel.

If cleaning areas contaminated by infected rat urine and/or feces, properly clean and disinfect areas using the steps below:

  1. Wear rubber or plastic gloves. While cleaning rat urine and/or feces, wear a high-efficiency particulate air (HEPA) filtered respirator.
  2. Do not sweep or vacuum rodent droppings. This will release particles into the air, which you could then breathe in.
  3. Spray droppings with an appropriately diluted household disinfectant or a mixture of 1 part bleach to 9 parts water. Follow the directions on the label of the household disinfectant to ensure proper dilution. Let the area soak for 10 minutes to make sure any virus within the droppings will be killed.
  4. Wipe up wet droppings with paper towels or a wet mop if dealing with a large area.
  5. Wash gloves in disinfectant and hot soapy water before taking them off.  Afterwards, wash your hands thoroughly.
  6. If a wet mop was used to clean the area, use disinfectant and hot soapy water to clean the mop.

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