Credit score: Jimmy Chan from Pexels
For the primary time, traces of the West Nile virus have been present in mosquitoes within the UK, in keeping with a report revealed this week by the UK Well being Safety Company.
Here is what you might want to know concerning the virus and the illness it causes.
What’s West Nile virus?
West Nile virus is a mosquito-borne virus first recognized in Uganda in 1937. It belongs to the identical viral household as dengue and yellow fever. The virus is mostly transmitted by Culex mosquitoes, significantly the species Culex pipiens, which primarily feeds on birds.
Birds are the first host for West Nile virus, and the virus spreads in a cycle from contaminated birds to mosquitoes after which again to birds. Sometimes, mosquitoes can transmit the virus to people or different animals.
Most human infections—round 80%—trigger no signs. When signs do happen, they’re often gentle: fever, fatigue, complications, physique aches and generally nausea. However in uncommon circumstances, round one in 150 infections, the virus may cause extreme sickness, together with encephalitis (irritation of the mind) or meningitis. Older adults, particularly these over 50, are most vulnerable to severe problems.
The virus can not usually be unfold from individual to individual, although uncommon circumstances of transmission have occurred by way of blood transfusions or from mom to child throughout being pregnant.
How did it get to the UK?
Though the precise route is not recognized, specialists consider the virus could have arrived within the UK through migratory birds contaminated elsewhere. The mosquitoes in all probability picked up the virus after feeding on these birds throughout their northward journey.
The detection was made as a part of a routine mosquito surveillance program run by the Animal and Plant Well being Company. Mosquitoes collected from marshlands in south-east England examined constructive in PCR (polymerase chain response) assessments, which detect fragments of the virus’s genetic materials.
It is necessary to notice {that a} constructive PCR check would not essentially imply the virus is infectious. After a mosquito turns into contaminated, the virus wants time—a number of days—to multiply contained in the mosquito earlier than it may be transmitted. And this course of is extremely temperature dependent.
Can the virus unfold within the UK?
The UK’s comparatively cool local weather has, till now, helped maintain mosquito-borne ailments at bay. At summer season temperatures of round 15°C, it will possibly take as much as 100 days for the virus to develop inside a mosquito—longer than the insect’s lifespan. In distinction, in hotter climates (above 30°C), this course of can take just some days.
For an area outbreak to happen, there would must be a important mass of contaminated birds and mosquitoes, with sufficient heat climate to maintain a number of cycles of transmission. Up to now, that hasn’t occurred within the UK.
However local weather change may alter the equation. With rising international temperatures and longer, hotter summers, the situations that enable viruses corresponding to West Nile to unfold could develop into extra widespread within the UK.
What’s taking place elsewhere?
West Nile virus was as soon as restricted to Africa and the Center East however has unfold considerably in current many years. Giant outbreaks have been recorded in nations together with Greece, Romania, Israel, Russia and the US.
The US outbreak started in New York Metropolis in 1999 when an uncommon variety of birds have been discovered useless in a metropolis zoo. A veterinary pathologist on the Bronx Zoo, Tracey McNamara, helped hyperlink the chicken deaths to the human diseases being reported.
Since then, the virus has unfold throughout a lot of the US, Canada and components of South America, leading to over 60,000 reported human circumstances, 28,000 hospitalizations and greater than 3,000 deaths.
In 2024, 19 European nations reported a complete of 1,436 native circumstances, most in males over 65, with 125 deaths. Most have been in Italy, Greece and Spain—nations with scorching, mosquito-friendly summers.
Outbreaks have been additionally reported in birds and horses, that are each vulnerable to the virus.
Ought to UK residents be involved?
Whereas the detection of West Nile virus in UK mosquitoes is noteworthy, specialists emphasize that the general public well being danger stays very low. No human circumstances have been reported within the UK up to now, and present summer season temperatures aren’t but conducive to sustained transmission.
The larger danger for many British individuals in all probability comes from journey—significantly to southern Europe, the place circumstances are rising.
Vacationers are suggested to take customary mosquito precautions: put on light-colored clothes, lengthy sleeves and trousers, and use insect repellent, particularly within the night when mosquitoes are most lively.
For now, the virus is unlikely to unfold extensively within the UK. However as local weather patterns shift, continued surveillance and public consciousness can be key to staying forward of the chance.
Offered by
The Dialog
This text is republished from The Dialog below a Artistic Commons license. Learn the unique article.
Quotation:
West Nile virus discovered within the UK for the primary time: What you might want to know (2025, Could 25)
retrieved 25 Could 2025
from https://medicalxpress.com/information/2025-05-west-nile-virus-uk.html
This doc is topic to copyright. Other than any honest dealing for the aim of personal research or analysis, no
half could also be reproduced with out the written permission. The content material is offered for data functions solely.