Three cases of Lassa fever have now been identified in the UK, and one person has sadly died after testing positive.
The cases are within the same family in the east of England and are linked to recent travel to West Africa.
However, health experts stressed that the overall risk is low.
Dr Susan Hopkins, chief medical adviser at the 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.”
Here we explain what Lassa fever is:
What is Lassa fever and what is the background of the disease?
Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus which can be serious and in some cases fatal.
Lassa fever was first discovered in the village of Lassa in Nigeria in 1969, when two missionary nurses became ill with the virus.
It is a viral infection carried by the Mastomys rat and mainly occurs in Sierra Leone, Liberia, Guinea, and Nigeria.
Causes: how do people become infected with the Lassa virus?
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 infected bodily fluids.
Crucially, transmission between people is also possible via blood, tissue, secretions or excretions, but not through touch.
According to Medical News Today, sharing needles may spread the virus, and there are some reports of sexual transmission.
What are the symptoms of Lassa fever?
Symptoms can include:
- bleeding in the gums, nose, eyes, or elsewhere
- difficulty breathing
- a cough
- swollen airways
- vomiting and diarrhoea, both with blood
- difficulty swallowing
- hepatitis
- swollen face
- pain in the chest, back, and abdomen
- shock
- hearing loss
- abnormal heart rhythms
- high or low blood pressure
- pericarditis
- tremors
- encephalitis
- meningitis
- seizures
Signs and symptoms of Lassa fever typically occur seven to 21 days after the patient comes into contact with the virus.
Is Lassa fever fatal?
According to the US government medical agency, the Centers for Disease Control and Prevention (CDC), Lassa fever is fatal in about 1 per cent of cases, while 20 per cent of cases progress to serious symptoms.
In more serious cases, death can occur within 2 weeks after the onset of symptoms due to multiple organ failure.
However, roughly 80 per cent of Lassa fever virus infections symptoms are mild and are undiagnosed.
Mild symptoms include slight fever, weakness, and headache.
The CDC says that the most common complication is deafness with “various degrees of deafness occurring in approximately one-third of infections, and in many cases hearing loss is permanent”.
What are the treatments for Lassa fever?
According to the World Health Organisation (WHO) the antiviral drug ribavirin is used as a way to effectively treat Lassa fever if given early on in the course of clinical illness.
There is currently no vaccine that protects against Lassa fever.
