Last week, it was announced that one person in England had died after contracting Lassa fever.
The UK Health Security Agency (UKHSA) confirmed that the person was among the three people south of the border who have contacted the virus.
It is believed that two of the cases are linked to recent travel to West Africa.
Work is now being carried out to identify close contacts of the three cases identified in the UK so far.
Here is what we know about the virus so far.
What is Lassa fever?
Lassa fever has been described as an ‘acute viral hameorrhagic illness' that is caused by the Lassa virus.
The virus has become endemic in a number of West African countries, and the UK has only previously recorded eight cases of Lassa fever since 1980.
So far, three cases of the virus have been recently recorded in England over the past few days.
The last recorded cases prior to these infections came in 2009, according to the UK Health Security Agency (UKHSA).
What are the symptoms?
The World Health Organisation has said that around 80 per cent of people who have become infected with Lassa fever have no symptoms.
One in five infections result in severe disease, where the virus affects several organs such as the liver, spleen and kidneys.
The incubation period of Lassa fever ranges from six to 21 days.
Symptoms usually begin with fever general weakness and malaise. After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough and abdominal pain may follow.
WHO experts say that severe symptoms include facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina and low blood pressure.
Shock, seizures, tremor, disorientation and coma may be seen in the later stages of infection.
Around a quarter of patients who survive the disease are said to suffer from deafness. In half of these cases, hearing returns partially after one to three months.
Death is said to occur within 14 days of onset infection in fatal cases.
One of three cases recently identified in England was fatal, the UKHSA confirmed last Friday.
Is it easy to catch?
People can become infected through exposure to food or household items contaminated with urine or faeces of infected rats.
The Lassa virus can also be spread through infected bodily fluids such as blood, urine, faeces or other bodily secretions.
There is no evidence of airborne transmission, similar to that of Covid-19.
UKHSA have said that the virus does not spread easily between people and the risk to the public is low.
Of all the cases previously identified in the UK, there was no evidence of onward transmission.
Dr Susan Hopkins, chief medical advisor at UKHSA said: “Cases of Lassa fever are rare in the UK and it does not spread easily between people. The overall risk to the public is very low.”
