Two people in England have been diagnosed with Lassa fever, and a third “probable” case is under investigation, the UK Health Security Agency has said.
It is the first time cases of the potentially deadly infectious disease, caused by the Lassa virus, have been identified in the UK for more than a decade.
One of the two confirmed cases has recovered, and the second is receiving specialist care at the Royal Free London NHS Foundation Trust. The “probable” case is being treated at Bedfordshire Hospitals NHS foundation trust, UKHSA said.
The cases are understood to be within the same family in the east of England and are linked to recent travel to west Africa. Lassa fever is an acute viral haemorrhagic illness. People usually become infected with Lassa virus through exposure to food or household items contaminated with urine or faeces of infected rats. The virus can also be spread through bodily fluids.
People living in areas of west Africa with high populations of rodents where the disease is endemic are most at risk of Lassa fever. Imported cases rarely occur elsewhere in the world. Such cases are almost exclusively in people who work in endemic areas in high-risk occupations such as medicine, or other aid workers.
Dr Susan Hopkins, the chief medical adviser at UKHSA, said: “We can confirm that two cases of Lassa fever have been identified in England, and a further probable case is under investigation. The cases are within the same family and are linked to recent travel to West Africa.
“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. We are contacting the individuals who have had close contact with the cases prior to confirmation of their infection, to provide appropriate assessment, support and advice. The UKHSA and the NHS have well established and robust infection control procedures for dealing with cases of imported infectious disease and these will be reinforced.”
Most people with Lassa fever will make a full recovery. However, severe illness can occur in some individuals. The Guardian understands that the UK’s High Consequence Infectious Disease Network is already engaged with the treatment of the infected individuals.
Symptoms are usually gradual, starting with fever, general weakness and malaise. After a few days there may be headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough, and abdominal pain , according to the World Health Organization. In severe cases there may be facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure.
Deafness occurs in 25% of recovered patients. In half of these cases, hearing returns partially after one to three months.
Before these cases, there had been just eight cases of Lassa fever imported to the UK since 1980. The last two cases occurred in 2009. There was no evidence of onward transmission from any of these cases.
Dr Sir Michael Jacobs, a consultant in infectious diseases at the Royal Free London, said: “The Royal Free hospital is a specialist centre for treating patients with viral haemorrhagic fevers, including Lassa fever. Our secure unit is run by a highly trained and experienced team of doctors, nurses, therapists and laboratory staff and is designed to ensure our staff can safely treat patients with these kind of infections.”
