Lassa fever in Nigeria: update 1

The Nigeria Centre for Disease Control and Prevention (NCDC) has reported 784 confirmed cases of Lassa fever (including 142 deaths) in the first 3 months of 2023. Ninety-six percent (751) of the cases have been recorded in Ondo, Edo, Bauchi, Taraba, Ebonyi, Benue, Plateau, Nasarawa and Kogio States. More than half have come from Ondo and Edo.

In addition to these confirmed cases, 3 826 suspected cases have been reported from 35 States.

Lassa fever is a type of viral haemorrhagic fever (VHF) endemic in parts of West Africa. Lassa virus is transmitted via the urine or droppings from infected rodents (Mastomys rats). Transmission can also occur via body fluids of infected people.

Advice for Travellers

The risk to travellers becoming infected or developing Lassa fever is extremely low, unless living in conditions of poor sanitation and overcrowding in rural areas where these rodents are usually found.

Travellers to known Lassa fever outbreak areas must be made aware of the risk of infection and transmission routes of Lassa virus which is most commonly through:

• ingesting or breathing in tiny particles in the air if it has been contaminated with infected rodent excretions, for example during cleaning activities such as sweeping
• touching objects soiled with infected rat excretions, and infecting open cuts or sores
• eating food which has been contaminated with rat excretions

Medical personnel travelling to work in an outbreak region must follow strict infection prevention control guidance.

Travellers returning from a Lassa fever outbreak area should seek rapid medical attention by contacting NHS 24 (Scotland) or NHS 111 (rest of UK) for advice prior to attending UK medical facilities if they develop fever and have:

• returned to the UK within 21 days from a region or area with a known outbreak of Lassa fever
• had contact with individuals infected with a VHF

For further information, see the TRAVAX Viral Haemorrhagic Fever page.