The parasite is spread by a species of fruit fly recently also recently found in southern England leading to fears it could spread to wild animals such as foxes that might act as “a reservoir” if it gains a foothold.
But humans can get infected too as it can jump between species.
Thelazia callipaeda also known as “the oriental eye worm” is increasingly common in Europe while the fruit fly Phortica variegata has been found in Gloucestershire, Kent and Berkshire.
The first known case of the eyeworm infection in the UK was found in an one-year-old male collie cross recently imported from western Romania just last July. It was later found in a 12-year-old female wire hair fox terrier had been in Lombardia and an eight-year-old female West Highland white terrier taken to the Dordogne that summer.
All had a UK pet passport and the emerging infections highlights the danger the free movement of pets poses to animals and humans in the British isles.
Now scientists have urged vets and GPs to be vigilant to the emerging parasitic threat and called for the loophole in the pet passport scheme to be closed so all pets travelling to high risk areas are given eye drops to kill the parasite.
Infections have been confirmed in Italy, France, Switzerland, Germany, Spain, Portugal, Bosnia and Herzegovina, Croatia, Romania, Bulgaria, Hungary, Greece, Belgium and Serbia.
In some locations, such as the Basilicata region in the “heel” of Italy, infection is “hyperendemic, with the reported prevalence in dogs exceeding 40 per cent.”
And infections in humans have been found in Spain, Italy, France, Croatia and Serbia demonstrating that it can jump from species.
Adult worms live in the eyes and tissues and infected animals show a variety of symptoms within two weeks, from mild conjunctivitis to severe corneal ulceration which, if untreated, can lead to blindness.
The fruit flies thrives in areas of oak and deciduous woodland and are most active during warmer, humid periods with peak transmission of the parasite typically late summer or early autumn in Mediterranean countries.
Postdoctoral Research Associate John Graham-Brown at the Liverpool Veterinary Parasitology Diagnostics, University of Liverpool, pointed out all three dogs received treatment and made a full recovery.
He said: “The risks of introducing such parasitic agents to the UK posed by importation and or travel of dogs abroad have been raised and illustrated on multiple occasions, while widespread media reports of large-scale illegal importation of dogs to the UK are clearly also of concern.
“The UK government’s pet travel scheme (PETS) facilitates the travel of dogs to and from countries in the EU without the need for quarantine.”
He said under the PETS dogs have to be vaccinated specifically against rabies and tapeworms.
He said: “Given the relatively free and regular movement of dogs into and out of the UK from mainland Europe and importation from rescue charities under this scheme, other pathogens, including T callipaeda, pose a significant threat to the UK canine population.”
He noted all three dogs had met all the requirements specified under PETS and added: “These three cases therefore demonstrate the risk of introducing T callipaeda to the UK through dogs being imported from and travelling to geographical locations where T callipaeda is known to be endemic.
“Furthermore, since T callipaeda is zoonotic and capable of infecting several other mammalian species, both people and cats should also be considered at risk of infection when travelling to such areas.”
He added ecological niche modelling back in 2006 identified southern England as suitable habitat for the fruit flies.
He said vets should urge dog owners to take “prophylactic measures” if travelling to high risk areas and concluded: “Vigilance is therefore advised when examining travelled dogs.
“Although effective diagnostic tests and treatments are available, more can and should be done to prevent this zoonotic pathogen from becoming endemic
in the UK.”
The study was published in the BMJ’s Veterinary Record.