Dog owners have been warned that taking their pets to Europe risks exposing them to an infectious parasite which turns animals blind.
Thelazia callipaeda has been described as a “significant threat to the UK canine population”, after vets reported three cases in dogs recently returned from the continent.
Transmitted by fruitfly, a species common in Britain, the disease is currently endemic in France, Italy, Spain and Greece, and more than six other European countries popular with British tourists.
The more people look for this disease, the more I believe they will find it
John Graham-Brown, Liverpool University
All three animals were in compliance with the requirements of the Pet Travel Scheme (PETS), also known as the Pet Passport, and experts last night called for the rules to be reviewed.
Owners of pets recently returned from Europe have been advised to look out for conjunctivitis and other signs of discomfort around their dogs' eyes.
Once diagnosed, the parasitic worm can normally be dealt with using drugs.
If left untreated for too long, however, it can cause the dog to go blind.
The disease was first discovered in Italy in 1989 and since 2010 the rate of reported European cases has significantly increased.
Veterinary academics say the pathogen is likely to be reaching “critical mass” on the continent, and that there are many more cases currently in the UK than the three currently reported, the first of which occurred last year.
John Graham-Brown, from Liverpool University, who led the research, said: “It’s definitely a risk.
“The more people look for this disease, the more I believe they will find it.”
The longer a dog lives with the disease untreated, the greater the risk it will be transferred to a fruitfly and then on to another dog, he said.
The risk of infection is compounded by the fact that not all animals display symptoms.
As well as dogs, T callipaeda is capable of infecting cats and wild creatures such as foxes.
The Pet Travel Scheme (PETS), governing the movement of animals from European Union countries, was introduced in 2001 and updated in 2014 to include a new style of passport and additional security measures.
Dogs travelling back to the UK are required to be treated for tapeworm between 24 hours and five days before they return, and their rabies vaccinations must be up to date.
In July 2016 it was reported that a collie cross had contracted T callipaeda after returning from Romania.
Writing in the BMJ, researchers also report that a fox hair terrier returning from northern Italy and a West Highland white terrier returning from a month in France also caught the disease.
Mr Graham-Brown, a doctoral student, said the PETS safeguards were “clearly not sufficient”.
“It’s a good time to have a discussion about whether they are strong enough for this disease and other diseases,” he said.
Mr Graham-Brown said: "So far, there has been only one strain of the infection round in Europe. But it's been spreading quite rapidly recently. We are not sure why.
"We do have this type of fly in the UK as well, so there is the potential for an infected dog to come back and give it to the fly here, and then it could spread."
T callipaeda is currently endemic in Italy, France, Switzerland, Germany, Spain, Portugal, Bosnia and Herzegovina, Croatia, Romania, Bulgaria, Hungary and Greece.
The BMJ paper warns that the infection of wild animals with the disease could form a “reservoir” of the pathogen, making it far harder to control thereafter.
It advises any owners concerned their dog may have been infected to seek immediate help from a vet.