A Case Series on Subcutaneous Dirofilariasis from a Tertiary Care Health Center in Kerala

Background: Filarial worms of the genus Dirofilaria are the primary cause of a rare infection known as human dirofilariasis. Dirofilaria are long, thin, parasitic round worms that infect a variety of mammals, and the infection is transmitted by mosquito bites. Specifically, Dirofilaria repens , Dirofilaria immitis , and Dirofilaria tenuis can infect humans as aberrant or accidental hosts. Case Series: We here report a case series of 10 patients diagnosed with subcutaneous dirofilariasis during a period of 7 years in a tertiary health center of Kerala. Seventy percent of the subjects were males, with the mean age of presentation being 36.7 years. The average duration of symptoms was 10 weeks, with 40% of subjects having a history of contact with pets. Examination: All patients had subcutaneous swelling, with the mean size of the lesion being 1.7 cm. There were two patients with subcutaneous swelling over their arms, two over their forearms, two over their parotid regions, and the other four patients had swellings over their forehead, neck, breast, chest wall, and knee, respectively. Differential Diagnosis included swellings of benign and inflammatory origin, such as lipoma, infected cystic swellings of sebaceous or epidermoid type, granulomas, and abscess. Management: Laboratory investigations were inconclusive, but in 40% of patients, ultrasonography revealed features suspicious of subcutaneous dirofilariasis. All 10 patients underwent excision biopsy of the local area, and diagnosis was confirmed with histopathological examination. Conclusion: Human subcutaneous dirofilariasis is a parasitic infection frequently reported, especially in the tropical region. Dirofilariasis should be considered in the differential diagnosis of subcutaneous swelling as failure to do so leads to unnecessary investigations. Adequate measures ensuring the prevention of mosquito bites should be implemented.