Key facts

Lassa fever is an acute viral illness caused by the Lassa virus

The disease is spread to humans primarily through contact with infected rodents or items contaminated with their urine and faeces

Person-to-person transmission can occur, especially in hospitals or clinics where there is poor infection control

Most people infected with Lassa virus experience mild symptoms, but the disease can be severe or fatal

Lassa fever is endemic in parts of west Africa

Overview

Lassa fever is an acute viral haemorrhagic illness that comes on quickly after infection. The Lassa virus, which causes the fever, belongs to the Arenaviridae virus family. The disease was first identified in 1969 in Nigeria, but has also been found in Benin, Ghana, Guinea, Liberia, Mali and Sierra Leone.

Lassa fever is a zoonotic disease, meaning that it spreads from animals to humans. The main animal reservoir for the virus is the multimammate rat ( Mastomys natalensis ), which is common throughout sub-Saharan Africa.…