Lassa fever UK: What are the symptoms and is it contagious?

The UK Health Security Agency has said the risk to the public from Lassa Virus is “very low”

The virus is usually contracted by contact with food or household items which have been contaminated by the urine or faeces of infected rats (Getty)

As the UK records new cases, for the first time since 2009, of the rare Lassa Fever the key message from public health leaders so far is that there is not yet cause for public concern.

What is Lassa?

Lassa Fever is an illness which is caused by the Lassa Virus. The virus, which is rat-borne, is usually contracted by human contact with food or household items which have been contaminated by the urine or faeces of infected rats.

Lassa Virus is found in West African countries where the disease is ‘endemic’, which means it is consistently present but limited to this region.

The diseases is a viral haemorrhagic one such as Ebola virus disease, malaria, shigellosis, typhoid fever and yellow fever.

What are the symptoms?

According to the World Health Organisation around 80 per cent of people who become infected with Lassa Virus do not experience symptoms. The overall fatality rate is one per cent.

However, those with Lassa Fever can experience, fever, general weakness in the first few days. After this they may experience a headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough, and abdominal pain.

Around one in five infections can result in severe illness which can include facial swelling, fluid in the lungs, bleeding from the mouth, nose vagina or gastrointestinal tract.

WHO said shock, seizures, tremor, disorientation and coma may be seen in the later stages, while deafness occurs in 25 per cent of recovered patients. In half of cases hearing will return.

It added: “The disease is severe late in pregnancy, with maternal death and/or foetal loss in more than 80 per cent of cases during the third trimester.”

There is currently no licensed vaccine for Lassa Fever according to WHO.

Where have the UK cases been so far?

There have been two confirmed cases in England so far, both in the East of England and a third ‘probable’ cases who is being treated at Bedfordshire Hospital.

The cases identified come from within the same family and have been linked to travel to West Africa.

What is the risk?

The UK Health Security Agency has so far said the risk to the public is “very low”.

The public health authority said the disease does not spread easily and that it is contacting individuals who have had close contact which the confirmed cases.

Prior to the new cases there have been just eight recorded in the UK since 1980 with the two most recently recorded in 2009.

Dr Sir Michael Jacobs, consultant in infectious diseases at the Royal Free London, said: ”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 medical or other aid workers.”