Meredydd Jones, 86, is a sheep farmer from Trecastle in Powys, Wales. In May 2016, he felt the worst pain of his life. Doctors found cysts in his lungs. A tapeworm caused them. He may have had the cysts for many years without knowing. Doctors removed one cyst from each lung in 2018 and 2019. He still has one cyst in his liver.

Dogs can get the tapeworm when they eat parts of a dead sheep with cysts. The dogs can then leave tapeworm eggs in their waste. People can get the eggs on their hands and then put them in their mouths. Cysts can grow inside the body. A person may not feel ill for 10 or 20 years. Regular medicine for worms in dogs and washing hands can lower the risk.

A team at Aberystwyth University will now study the disease in mid Wales. They will put GPS trackers on sheepdogs. The trackers will show where the dogs go and if they visit other farms. The team will also test dog waste. They hope to learn how common the tapeworm is and how it moves between farms. This may help protect farmers and other people.