Lassa fever

Key facts

• Lassa fever is an acute viral haemorrhagic illness of 1-4 weeks duration that occurs in West Africa.

• The Lassa virus is transmitted to humans via contact with food or household items contaminated with rodent urine or faeces.

• Person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevent and control measures.

• Lassa fever is known to be endemic in Benin (where it was diagnosed for the first time in November 2014), Guinea, Liberia, Sierra Leone and parts of Nigeria, but probably exists in other West African countries as well.

• The overall case-fatality rate is 1%. Observed case-fatality rate among patients hospitalized with severe cases of Lassa fever is 15%.

• Early supportive care with rehydration and symptomatic treatment improves survival.