Ducks and "ducks fleas"

I like ducks, but not really what we call "ducks fleas" (swimmer's itch). Putting the rowing boat in the water a few days ago I probably picked up one of them. A big red spot on my leg is the result. 

It's a worm-like parasite whose usual host is the ducks that live in the lake, mainly in the shallow and warm water. Some parasite larvae can penetrate ‘mistakenly’ through human skin rather than finding their usual host – a duck. Luckily the parasite dies, but the body can develop an allergic reaction to the parasite and the rash.