Human Dirofilariasis- An Underrecognized Zoonosis

Dirofilariasis is a rare zoonotic disease caused by the filarial nematode of the genus Dirofilaria. It is an uncommon zoonosis which was previously reported in endemic areas. However, with climate change, it is being reported in non-endemic areas too. Domestic animals like dogs are their natural hosts and in rare instances, their microfilariae may spread by mosquito bite to humans where they may cause subcutaneous nodules or severe cardiopulmonary disease depending on the species. Dirofilariasis, caused by the species Dirofilaria repens, presenting clinically as subcutaneous nodules have been reported in the face including the oral cavity and orbital area. A 60-year-old female patient reported with the complaint of a facial swelling of one month duration. A non-tender firm swelling was noted in the buccal vestibule in relation to the mandibular left canine and premolars. An odontogenic source of infection was ruled out, and an excisional biopsy was done. Cross-sections of the adult Dirofilaria repens worm with an eosinophil-rich granulomatous reaction was identified on microscopy.