Tick-borne encephalitis is “likely” to be present in the UK, health officials have said, after the first domestically acquired case of the virus was confirmed in Yorkshire.
The assessment, published by a joint UK Health Security Agency (UKHSA) and Defra committee, based its findings on both human cases and the detection of the virus in ticks in several areas of the country.
Tick-borne encephalitis virus (TBEV) is already common in many parts of Europe, and is an important cause of viral infections in the central nervous system, according to the World Health Organisation.
It can cause a range of illnesses from completely asymptomatic infection, to mild flu-like illness, to severe infection in the central nervous system such as meningitis or encephalitis.
Encephalitis is an uncommon but potentially deadly condition in which the brain becomes swollen.
The joint committee added that the risk to the public is very low.
There have been three cases of probable or confirmed TBEV in England since 2019, with the first confirmed case in Yorkshire in 2022, and a probable case detected in the Loch Earn area of Scotland in the same year.
The virus has also been detected in the Hampshire/Dorset and Norfolk areas but may also be present in other parts of England as the tick species which carries the virus is widespread in the UK.
Ian Jones, professor of virology, University of Reading, said wearing appropriate clothes “essentially removes the risk”.
“Tick-borne encephalitis virus was reported in ticks in Thetford Forest in 2019 and today’s update would suggest that it has now become established at other sites and caused sporadic disease in people,” he said.
“Genetically the UK viruses have been close to European or Scandinavian strains so they may have originally arrived from the near continent in ticks attached to birds.
“The virus is found naturally in some ticks and gets transferred to a person if they are bitten (only if the tick is infected), usually on bare arms and legs whilst walking through undergrowth. Wearing appropriate clothing essentially removes the risk.”
Prof Jones added: “Now here, it’s unlikely that TBEV will disappear, but the general threat level is very low and there is no reason to suppose cases in people will be any more than sporadic in nature.
“A vaccine is used in areas of high incidence in Europe and could be considered here for individuals with outdoor occupations in areas where the virus is found.
“For the general public however the risk is minimal.”
Dr Meera Chand, deputy director at the UK Health Security Agency, said: “Our surveillance suggests that tick-borne encephalitis virus is very uncommon in the UK and that the risk to the general population is very low.”
Members of the public who become unwell after a tick bite have been told to seek GP advice, and to seek urgent medical attention if they have symptoms of meningitis, including severe headache, stiff neck, pain looking at bright lights, or if they develop sudden neurological symptoms including a seizure, sudden confusion, weakness, or facial dropping.
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