What is Lassa fever and what are the symptoms after UK case

A Lassa fever case has been confirmed in a person who recently travelled to England from Nigeria

UKHSA is working to track individuals who may have been in contact with the infected person during their time in England (AFP via Getty Images)

A viral illness called Lassa fever that can cause Ebola-like symptoms has been confirmed in a person who recently travelled to England from Nigeria.

Officials are now checking for any possible cases of the virus and are working to track individuals who may have been in contact with the infected person during their time in England.

There have been very few cases of Lassa fever ever detected in the UK – with the last cases recorded in 2022.

Lassa fever is more common in Nigeria and several other countries on the west coast of Africa, including Liberia and Guinea.

How does Lasser fever spread?

Lassa fever is carried by a particular type of rodent, called the Mastomys.

The rat-borne virus is usually contracted by humans through food and water.

It does not spread easily between people and the overall risk to the UK population remains “very low”, Dr Meera Chand, deputy director at UK Health Security Agency (UKHSA) said.

However, it can be transferred through blood, saliva, urine or semen.

UK officials have not confirmed how long the infected individual remained in England or which part of the country they visited.

What are the symptoms?

Lassa fever causes acute infections which can range from very mild symptoms through to a severe viral haemorrhagic fever.

The virus, which can trigger seizures and make women bleed from their vagina, also causes difficulty breathing, vomiting, facial swelling, pain in the chest, back and stomach.

However, most people with Lassa fever experience mild symptoms, such as fever, tiredness, headaches, a sore throat and generalised pain.

Symptoms usually occur between one and three weeks after contracting the virus. But in the majority of cases (80 per cent) people who contract the virus experience no symptoms at all, according to the World Health Organization (WHO).

Although most people do make a full recovery the virus can cause more severe illness and even be fatal.

Out of those recovering, about a quarter have hearing loss, which improves within three months in about half of these cases.

Pregnant women in particular are at risk of getting seriously ill. Catching the virus in the third trimester of pregnancy can increase the risk of stillbirth and miscarriages and even a higher chance of death for pregnant women.

When was it last detected in the UK?

Lassa fever was last detected in the UK in 2022 when a newborn baby died in Bedfordshire, at Luton Dunstable Hospital.

The child was the third member of the family to contract the virus after they returned to the UK from west Africa.

These three cases were the first recorded in the UK since 2009.