Why Is UK Gearing Up Against The Lassa Fever?

Lassa fever have been in the UK in small numbers in 2022 and the people are alert again after a traveller to England, who has since returned to Nigeria is known to have been infected. The virus does not spread easily between humans and the overall risk to the public is very low. However, the UK Health Security Agency (UKHSA) is also very unlikely to have had any exposure, they have confirmed.

The UKHSA has ensured that it is "working at speed" to find anyone who may have had contact with the person who had Lassa fever. The officials have also said that they are "well-equipped to identify people who have Lassa fever."

The deputy director at the UK Health Security Agency, Dr Meera Chand, said, "Our health protection teams are working at pace to get in touch with people who were in contact with this individual while they were in England, to ensure they seek appropriate medical care and testing should they develop any symptoms. The infection does not spread easily between people, and the overall risk to the UK population is very low."

What Is Lassa Fever?

As per the World Health Organization (WHO), Lassa fever is an acute illness caused by the Lassa virus that was originally identified in 1969 in Nigeria. This virus belongs to the family Arenaviridae. It is a zoonotic disease, which means humans can become infected from contact with infected animals. The animal reservoir, or host, of Lassa virus is a rodent. They are of genus Mastomys, and are known as multimammate rates, which do not become ill when infected from Lassa virus, but they can shed the virus in their urine and faeces, infecting others.

The WHO also notes that around 80% of people who have been infected with Lassa virus have no or mild symptoms. Only 1 in 5 infections result in severe disease and it can affect multiple organs, such as live, spleen, and kidneys.

How Does The Transmission Happen?

Humans primarily contract the Lassa virus through exposure to food or household items contaminated with the urine or feces of infected Mastomys rats, or through direct contact with these rodents.

Mastomys rats are common across West Africa, often living in and around homes, food storage areas, fields, and cleared forests. While they are the primary reservoir of the virus, Lassa virus has also been found in other rodent species, suggesting they may play a role in transmission.

Although less common, human-to-human transmission can occur through direct contact with the blood, urine, feces, or bodily fluids of an infected person, particularly in healthcare settings. Contaminated medical equipment, such as reused needles, can also spread the virus. Health workers face a higher risk if infection control measures are inadequate.

In some cases, Lassa virus may persist in the semen of recovered male patients for a few months, though no documented transmission has occurred through this route.

There is no epidemiological evidence of airborne transmission between humans.

What Are The Common Symptoms?

The symptoms show within 2 to 21 days of being infected, which include:

• Starting with a gradual fever
• General weakness
• Headache and malaise.

Then after a few days, you may experience sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough and abdominal pain.

If you have severe case, your face may swell, fluid can be filled in lung, and there may be bleeding from mouth, nose, vagina, or gastrointestinal tract. You may also develop lower blood pressure.