The UK government has issued a new contingency plan for West Nile virus (WNV) after mosquitoes carrying the potentially lethal disease were detected in the country. The virus, which has no available vaccine, claimed 67 lives across Europe over a 12-month period.
Detection and Current Risk
Officials from the UK Health Security Agency (UKHSA) confirmed the presence of WNV in mosquitoes in the UK. However, they stressed that no human cases have been acquired domestically. The risk to the population remains very low, though it is expected to rise with climate change, particularly given the virus's presence in neighbouring countries.
WNV is primarily transmitted through bites from infected Culex mosquitoes, which acquire the virus from birds. While 80% of infected individuals show no symptoms, about 20% develop mild flu-like illness. In rare cases (less than 1%), the virus can cause severe neurological diseases such as meningitis or encephalitis, which can be fatal.
Transmission and Symptoms
Humans can become infected through mosquito bites, and less commonly via mother-to-child transmission, breast milk, blood transfusions, or organ transplants. Acute infection may cause fever, headache, muscle aches, and a rash. Severe symptoms include high fever, neck stiffness, confusion, coma, tremors, muscle weakness, vision problems, numbness, and paralysis.
Groups at higher risk include individuals over 50 years old and those with underlying medical conditions such as cancer, diabetes, hypertension, and kidney disease. The case fatality rate is highest in patients over 70.
Geographic Spread in the UK
The mosquito species capable of transmitting WNV, Culex pipiens, has been found across the UK, particularly along the Thames estuary, Suffolk, the Cambridgeshire Fens, and the south coast in Sussex and Hampshire. Its distribution is expanding, likely due to climate change.
Government Response
The UKHSA has advised GPs to report any suspected cases immediately. The contingency plan focuses on prevention, as no human vaccine is available. Officials urge the public to take measures to avoid mosquito bites, especially during warmer months.
