A HOSPITAL patient in England has died from a confirmed case of Lassa fever – the third case to be identified in the UK in the last few days.
All three cases of the potentially fatal disease are understood to be linked to recent travel to West Africa.
The news means it is the first time the disease has been found in Britain in more than a decade.
Here's everything you'll need to know about the illness.
WHAT IS LASSA FEVER?
Lassa fever is a “viral haemorrhagic fever” (VHF), like the more famous Ebola. It was first described in the 1950s, and identified in 1969. It is a single-stranded RNA virus.
The disease is “zoonotic”, meaning it passes from animals to humans. In the case of the Lassa virus, the host animal is a rodent of the genus Mastomys, commonly known as the “multimammate rat”.
The World Health Organisation (WHO) says that around 80% of people who contract the disease exhibit no symptoms. However, the remaining 20% of infections result in severe disease.
It has a mortality rate of 1%, the WHO says.
Lassa virus disease is much more severe for women late in pregnancy, with maternal death and/or foetal loss in more than 80% of cases during the third trimester.
WHAT ARE THE SYMPTOMS?
Lassa fever’s symptoms are “varied and non-specific”, according to the WHO, which makes diagnosis difficult. It can be hard to distinguish between Lassa and other VHFs such as Ebola virus disease, malaria, shigellosis, typhoid fever and yellow fever.
When symptomatic, the onset of Lassa fever is usually gradual, starting 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. In severe cases facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop.
Shock, seizures, tremor, disorientation and coma may be seen in the later stages. Deafness occurs in 25% of recovered patients, with hearing returning partially over a series of months in 50% of those incidents. Hair loss may also occur during recovery.
The virus can have an impact on organs such as the liver, spleen and kidneys. Death usually occurs within 14 days in fatal cases.
CAN IT BE CURED?
There are as yet no vaccines for Lassa fever, but some are in development.
The WHO says that the antiviral drug ribavirin has been used in some nations as a therapeutic agent, but there is “no evidence” to support its role as a treatment for the disease.
Prevention is seen as the best way of dealing with the Lassa virus. This involves a high level of hygiene, and keeping food and other goods away from where it may come into contact with the rats carrying the virus.
SHOULD WE BE WORRIED?
No, is the short answer. The UK has seen just eight cases of Lassa fever imported since 1980, with the two most recent having occurred in 2009.
The UK Government said that there was no evidence of onward transmission in any of these cases. However, person-to-person transmission is possible.
The two (and possible third) currently being investigated are all within a single family in the East of England and have been linked to recent travel to West Africa.
The disease is endemic (always present in the background) in several nations on that side of the continent. Infection usually follows contact with food or household items contaminated with urine or faeces of infected rats.
Lassa fever is known to be endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, Togo and Nigeria, but probably exists in other West African countries as well, according to the WHO.
Dr Sir Michael Jacobs, consultant in infectious diseases at the Royal Free Hospital in 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.”
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