9 Apr 2025
Echinococcus granulosus, which causes hydatid disease in humans, traditionally confined to hotspots in Wales and Scotland – but some fear it may now be elsewhere.
Paul Imrie
Job Title
A 3D rendered, medically accurate illustration of Echinococcus granulosus. Image: Sebastian Kaulitzki / Adobe Stock
Vets and medics want increased molecular-level surveillance for a zoonotic parasite that could have spread outside traditional UK hotspots.
Echinococcus granulosus causes hydatid disease, or cystic echinococcosis, in humans – a chronic condition that can cause cysts in the liver and lungs, and less frequently the bones, kidneys, spleen, muscles and central nervous system.
On 6 April, Echinococcus species were added to a list that laboratories testing human samples in England are required to report to the UK Health Security Agency.
The tapeworm can be seen across the world, but in Europe is most prevalent in sheep-farming areas, including the Balkans, parts of eastern Europe and around the Mediterranean.
The UK has had traditional E granulosus hotspots in the Western Isles and Powys, and previous worming and awareness programmes have targeted them. But prevalence outside these areas is unknown.
Vet Marisol Collins, lecturer in veterinary pharmacology at the University of Liverpool, devoted her PhD thesis to the tapeworm and is hoping her research will soon be published in a peer-reviewed journal.
Speaking at a packed Elanco-sponsored clinical session at BSAVA Congress and Expo 2025, Dr Collins outlined her work with sheep farms, hunts, zoos and slaughterhouses, which found evidence of E granulosus in and outside the known areas.
She said: “The work that we did supports that re-emergent picture in Wales – that seesaw that we’ve seen when control programmes start, stop and are not happening in a controlled way.
“We know that, from what I found, we potentially have this parasite outside of those known hotspots. But remember, this wasn’t a prevalence study. We know that those common issues are there with respect to risk factors, and all of these things together are basically a clarion call to say we need more than just a torch shone to the core of the room. We need to switch a light.
“We need proper prevalence studies at molecular level to see where this parasite is.”
Ian Wright, chairperson and director of the European Scientific Counsel Companion Animal Parasites, told the session risk from E granulosus had been perceived as limited to farmers and hunt kennel workers, because of raw offal feeding, close contact and dogs having access to fallen stock.
But the session also covered concerns over spread through dogs off lead on pasture, poor disposal of faeces leading to food contamination or inadequately frozen raw dog diets.
Dr Wright said: “The issue with Echinococcus is that those microscopic eggs, when they’re passed in the faeces, are immediately infective. It’s not a parasite that is well suited for test and treat, because you’ve already got shedding with the potential for human zoonotic exposure.
“It is still useful to test, though, for surveillance. We’re not relying on it, we’re relying on the risk-based approach to decide whether to treat, but it will help to inform us where the parasite is in the country, which I think would be really useful.”
Laura Nabarro, consultant in parasitology, tropical medicine and infectious diseases at UCL Hospital for Tropical Diseases, outlined a chronic case of cystic echinococcosis in a 57 year old woman, who required weeks in hospital and months in recovery after likely contracting the disease in the UK.
Dr Nabarro said she suspected 85% to 90% of UK cases were still acquired abroad, but new data collection and closer work between medics and vets would help in the future.
