The parasite Dirofilaria repens is a roundworm that primarily attacks the subcutaneous tissue of dogs and causes lumps in the skin, swelling, and itching. Dogs, cats, foxes, wolves and martens can be infected in addition to dogs. "In humans, 16 cases of human dirofilariosis have been recorded since the year 2000, but the dark figure is definitely higher", says the lead author Katja Silbermayr. Humans, however, are so-called dead end hosts; the parasite does not reproduce in humans and therefore poses no major risk.