Researchers investigate whether beavers spread harpest - no connection found

This year, 69 cases of harpest have been confirmed in Västerbotten, and there are many indications that it will be a record year.

The infectious disease is caused by a bacterium that can be carried by rodents, and mosquitoes can also spread the disease.

In the past, it has been seen that when the population of hares and other rodents is high, more people become infected.

But 2023 was a low year for rodents, but despite this there were an unusually high number of cases of harpest.

Sampled water

To find out more about how the infection is spread, researchers in Umeå have investigated whether beavers contribute to the spread of the infection because harpest is spread via mosquitoes that thrive in the water environments that beavers create with their ponds.

- We have sampled a lot of water around Sweden, both in beaver wetlands and other waters. Then we compared the occurrence of harpest bacteria, says Lovisa Hökby.

Part of a European project

But the researchers have thus not seen that beaver dams mean any increased spread of herpes. The research is part of a larger European project that also looks at mosquitoes and small rodents.

- We want to know how these different sources of infection are connected. Where the bacteria are found in nature and how they are connected to the organisms that can spread the infection further, says Lovisa Hökby.