Three people in the UK have been diagnosed with Lassa fever, and sadly one of them has died. But what is this illness and should we be worried?
Lassa fever is an acute viral illness caused by Lassa virus, named after a place in Nigeria where it was first discovered in 1969. People usually become infected with Lassa virus through exposure to food or household items contaminated with urine or faeces of infected rats – present in a number of West African countries where the disease is endemic. The virus can also be spread through infected bodily fluids.
The UK Health Security Agency (UKHSA) is contacting the individuals who have had close contact with the cases prior to infection.
A Bedfordshire Hospitals NHS Foundation Trust spokesperson said: “We confirm the sad death of a patient at our trust, who had confirmed Lassa fever. We send our deepest condolences to their family at this difficult time.
“We will continue to support the patient’s family and our staff and are working closely with colleagues from UKHSA to undertake a robust contact tracing exercise.”
Should we be worried about Lassa fever?
According to the Centres For Disease Control in the US, approximately 100,000 to 300,000 infections of Lassa fever occur globally every year, with approximately 5,000 deaths.
But the UKHSA says the risk to the general public remains very low. Since 1980, there have only been eight cases of the virus in the UK, with the last two occurring in 2009.
Those with the greatest risk of transmission are people exposed to the rodent – a multimammate rat – which often occurs in Sierra Leone, Liberia, Guinea, and Nigeria.
People living in endemic areas of West Africa with high populations of rodents 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 medical or other aid workers.
What are the symptoms of Lassa fever?
Infection is mild or asymptomatic in 80% of cases, but it can cause severe illness and is fatal in around 1% to 3% of patients. The incubation period for disease is usually between seven and 10 days, with a maximum of 21 days.
The onset of illness builds gradually, with:
- Fever and shivering
- Discomfort
- Headache
- Generalised aching
- Sore throat
- Nausea, vomiting, diarrhoea, or cough can accompany these symptoms.
An important early symptom is the appearance of patches of white or yellowish exudate (fluid) and occasionally small vesicles or shallow ulcers on the tonsils and pharynx.
As the illness progresses, the body temperature can rise to 41ºC with daily fluctuations of 2ºC to 3ºC.
Extreme lethargy and exhaustion can occur in severe attacks. In such cases, bleeding from gums, eyes or nose can occur. They may also experience respiratory problems, swelling, and even rarer neurological problems such as loss of hearing. Death may occur in cases of multi-organ failure.
If you’ve been to a high-risk area or know someone who has, displaying such symptoms, consult with a doctor immediately.
There is treatment available to treat the virus, most effective when administered early.