West Nile virus, a potentially fatal mosquito-borne infection for humans, has recently been detected in the UK for the first time. The UK Health Security Agency (UKHSA) in collaboration with the Animal and Plant Health Agency (APHA) made this discovery after identifying fragments of the virus in Aedes vexans mosquitoes collected from wetlands on the River Idle in Nottinghamshire in July 2023.
According to Arran Folly at APHA, the detection of the virus was serendipitous during routine sample testing. Additional screening will now be conducted in the area to monitor any further instances of the virus. Typically, APHA’s screening efforts are focused on the south and east of England due to the warmer weather conditions that are conducive to the spread of infections like West Nile.
West Nile virus can infect both humans and horses through mosquito bites. Symptoms in humans can range from fever, headache, body aches, vomiting, and diarrhea, to more severe cases of brain and spinal cord inflammation that can be fatal. Currently, there is no approved vaccine for humans against this virus.
While the virus has only been detected in two mosquito samples and there is no evidence of human or equine infection in the UK, UKHSA has emphasized that the risk to the public is very low. However, healthcare workers are advised to test individuals with unexplained brain inflammation (encephalitis). Meera Chand at UKHSA mentioned that the detection of West Nile virus in the UK was not unexpected, given its widespread presence in Europe.
The spread of West Nile virus is closely linked to high temperatures, droughts, and warm winters, all of which have become more common in northern Europe. The recent warm weather in the UK could facilitate the re-emergence of the virus. Scientists have been on high alert for the arrival of West Nile virus since the detection of a similar virus, Usutu, in London in 2020. Matthew Baylis from the University of Liverpool believes that the virus was likely brought to the UK by a bird and may be circulating among multiple mosquito species.
While there is a small risk of infection for humans and horses, Baylis assures that it will be rare, citing the limited number of cases in other northern European countries. The vigilance of UK health authorities and ongoing monitoring efforts will be crucial in containing the spread of West Nile virus in the country.
