Four dogs were diagnosed with babesiosis in Harlow in Essex, who were all exercised on the same patch of land.
It has never been recorded before in the UK, according to the vet who treated the dogs.
All four survived but were "seriously ill" and two needed blood transfusions, vet Clive Swainsbury said.
He said Public Health England and the Department for Environment, Food and Rural Affairs (Defra) helped identify the disease after finding the ticks in an area just south of the town centre.
"We are doing everything we can but every tick will make up to 1000 eggs.
"It's not just Harlow that needs to be concerned, in time it will spread to the rest of the country," Mr Swainsbury, who works for Forest Veterinary Centre in Harlow, said.
What is Babesiosis?
It was compulsory for imported dogs to be treated for ticks before entering the UK and Ireland until 2011. When this requirement was dropped to comply with EU regulations, vets warned that outbreaks of exotic tick diseases were likely to follow.
The Animal and Plant Health Agency, which is an executive agency sponsored by Defra, confirmed the affected animals had not been abroad.
"These particular dogs have not travelled outside England raising the possibility they have become infected within the country.
"We are providing support to veterinary practices to identify the possible source of infection," a spokesman said.
Harlow Council has warned dog owners to avoid the land between Second Avenue and Third Avenue and Tendring Road.
The BBC has contacted Defra but it is yet to comment.
A tick-borne disease that is often fatal in dogs is likely to spread around the UK, a vet has warned.