In the clip, Olof Lindstrand tells more about the parasite.

Shallow water and high temperatures - these are fine fish for the small parasite that is spread via seabirds.

It is not visible, but is still there, swimming in the surface water.

Timrå municipality has now received several reports about bathing places where the parasite is found. 

Information about the parasite can be found on the Swedish Public Health Agency's page.