Subcutaneous dirofliariosis is caused by the filarial nematode Dirofilaria repens, a close relative of Dirofilaria immitis, the so called heartworm. Like D. immitis, Dirofilaria repens is transmitted through a mosquito bite.

Dirofilaria repens is an emergent zoonotic pathogen, although infection is not transferred directly from dog to man but by mosquito vectors. Infection in humans usually results in a subcutaneous nodule in the upper part of the body, close to the eyes as well as under the conjunctiva. Less often, inner organs can be affected, including the lungs. Human cases are reported from more than 30 countries. In Europe, the highest numbers of cases are reported from Italy, France, Greece and the Ukraine.


Dirofilaria repens (Nematoda: Filaroidea, Onchocercidae) is a whitish and filariform worm (male 5-7 cm, female 6-17 cm), localized as adult mainly in the subcutaneous connective tissue of the dog. Other animals affected are the red fox (Vulpes vulpes) and more rarely the cat. The microfilariae are found in the peripheral blood, waiting to be picked up by a mosquito. The main representative of the genus Dirofilaria is Dirofilaria immitis, commonly called heartworm and infectious agent of heartworm disease.




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