A disease that can harm the brain, and is spread to humans by tick bite, has been identified on the Hampshire-Dorset border.
Public Health England (PHE) found the encephalitis virus in British insects for the first time, after a European visitor fell ill when she was bitten in the New Forest area.
It says the risk to people is "very low" - but the organisation is investigating how common the virus might be.
The disease is more widespread in areas like South East Asia and Scandinavia - with travellers paying up to £200 for the pair of jabs advised in high-risk areas.
Doctor Ava Easton - the Encephalitis Society CEO - told The Breeze the jab for the disease is not currently necessary in the UK
The ticks were also found in East Anglia's Thetford Forest - experts believe they arrived into the country through migratory birds.
They can also live in other animals, such as dogs, and in undergrowth.
Most people who catch the encephalitis virus will either have minimal or only mild flu-like symptoms, but it can affect the central nervous system and is sometimes fatal.
For the first time, tick-borne encephalitis virus (TBEV) has been detected in #ticks in the UK. Read our latest #DiseaseDetectives blog to find out more about the importance of monitoring ticks and mosquitoes for new health threats: https://t.co/hQ5V5x3GO5— Public Health England (@PHE_uk) October 30, 2019
Dr Nick Phin, from PHE, said: "These are early research findings and indicate the need for further work.
"We are reminding people to be 'tick aware' and take tick precautions, particularly when visiting or working in areas with long grass such as woodlands, moorlands and parks."