DEADLY and paralysing West Nile virus has been spotted in UK mosquitoes for the first time.
The bug is spread that are common in , the Middle East and South Asia.
Many people won’t get symptoms at all but some may be struck with flu-like aches and pains, and fever.
The virus can cause severe, life-threatening illness in around one in 150 people who catch it, according to the World Organization (WHO), which may lead to or even death.
Scientists identified fragments of the virus in the genetic material of UK for first the time.
While there have been other cases of West Nile virus on British soil, these have usually been a result of mozzie bites acquired in different countries, where the disease-carrying critters are abundant.
Over the last 25 years, only seven cases have been brought into the UK by – and none have caught it locally.
While West Nile virus is endemic in Africa, the Middle East, West and Central Asia, the US and , mosquitoes carrying the disease have gradually spread through – including in the north, where temperatures are lower.
were found on the banks of the River Idle, near Gamston in , where flooding and standing water encourages them to gather.
Scientists from the UK Health Security Agency (UKHSA) gathered them in July 2023 and pooled into 200 groups of 10 for testing.
Only two out of 200 groups that were tested showed traces of the virus.
UKHSA stressed that it the risk to Brits was low, as there have been no reports of the virus spreading to people.
Dr Meera Chand, UKHSA deputy director for travel health and emerging infections, said: “While this is the first detection of West Nile Virus in mosquitoes in the UK so far, it is not unexpected as the virus is already widespread in Europe.
“The risk to the general public is currently assessed as very low.
“Vector research of this kind is designed to give us early warning of potential threats so that we can enhance our disease surveillance and control activities and ensure patients receive appropriate testing.”;;
The health watchdog said healthcare professionals should test patients with encephalitis of unknown cause as a precaution through UKHSA’s Rare and Imported Pathogens Laboratory.
Prof Tom Solomon, from the NIHR Health Protection Research Unit on Emerging Infections and the Pandemic Institute in said West Nile virus mostly causes a flu-like illness in people.
But it can also “infect people with no symptoms at all”;;.
People infected with the bug may experience:
- Headaches
- Body aches and joint pain
- Vomiting
- Diarrhoea
- Rash
- Fever
- Swollen lymph nodes
Symptoms typically take two to 14 days to appear after infection and should go away within three to six days, according to the UK Health Security Agency.
Prof Solomon added: “In a small proportion of patients, the virus can cause neurological disease, which may lead to paralysis or even death.
“Unfortunately, there is no specific treatment.”;;
Fewer than 1 per cent of people infected with West Nile virus will develop disease in the brain and nervous system, according to UKHSA.
This may be , encephalitis with high fever, neck stiffness, disorientation or confusion, severe muscle weakness, tremors, convulsions, paralysis and coma.
People over 50 or with health conditions like,,, orare at higher risk of serious illness.
Meanwhile, patients aged over 70 are at highest risk of death.
How is West Nile virus spread?
The bug is primarily spread through the bites of infected mosquitoes.
According to UKHSA, humans are considered dead-end-hosts, which means people infected with West Nile virus can’t transmit the virus back to mosquitoes.
This means that if someone gets overseas and travels back to the UK, this won’t lead to further transmission of the illness.
With the bug being spotted in UK mosquitoes for the first time, experts still aren’t especially worried that this will lead to widespread transmission of West Nile virus in the UK.
Dr Robert Jones, assistant professor at the London School of Hygiene and Tropical Medicine, said: “There is currently no evidence that these fragments of genetic material are linked to any human cases of West Nile virus infection.”;;
Professor Paul Long, a microbiologist at King’s College London, added: “Although virus-infected mosquitoes have been found in the UK there’s no evidence yet that these mosquitoes will survive in the UK climate, although prolonged warm does increase the chances.”;;
In Europe – where cases of West Nile virus have been identified in countries including , and – cases tend to be highest in and early autumn, when mosquitoes are most active.
In very rare cases, the illness can passed on through blood transfusion, or vertical transmission from mother to child during , delivery or .
In 2024, 1,436 locally acquired cases were reported across 19 EU countries — including , and – resulting in 125 deaths.
That’s a sharp rise from 802 cases in the same period last year, suggesting the virus is gaining ground.
