The threat amongst the berries – how dangerous is the fox tapeworm?

The fox tapeworm, Echinococcus multilocularis, has become more common in red foxes in Europe. In 2011, SVA (the National Veterinary Institute) discovered it in a Swedish fox for the first time.

Usually, the parasite is transferred between various canines and rodents. In Europe, the red fox is the parasite’s most important definitive host while various rodents act as intermediate hosts. It can be transferred to humans for example via dogs who have the parasite’s egg in their fur, or via berries that we pick and eat directly from the shrubs.

Johan Höglund, professor at the Department of Biomedical Sciences and Veterinary Public Health, is one of the researchers within the field. He thinks the risk of being infected in Sweden today is practically non-existent.

“I’m still taking my forest walks,” he says. “With today’s knowledge of the parasite, we know it’s still is extremely rare in Sweden. Furthermore, most knowledge indicates that it has always existed in the country at a low level.” He goes on to dismiss the idea that the fox tapeworm came into the country via imported dogs.

Humans getting infected is rare, but if you’re unlucky enough to get sick, it is important to receive treatment. Untreated, the infection is lethal. The parasite grows in the liver, or sometimes in the lungs, slowly like cancer. Only after 10­­–15 years does the infection reveal itself in the form of symptoms from the affected organ.

When SVA found the tapeworm in 2011, they began mapping the spread of the fox tapeworm in Sweden. In 2013, the EU project EMIRO was established, coordinated by Johan Höglund. Its purpose is to investigate how various Swedish rodents affect the parasite’s life cycle. Andrea Miller at the Department of Biomedical Sciences and Veterinary Public Health has been a doctoral student on the project. She will soon be defending her doctoral thesis, the purpose of which has been to examine how the fox tapeworm is transferred.

Our berry breaks in the forest, then, are not acutely threatened, and our dogs are not affected by the parasite. And, above all, if we do get sick, there is treatment to be had.