Dirofilaria repens Parasite: Review with Emphasis on Ultrasound Findings with Looking for Worm Mobility

Human dirofilariasis is caused by infection with a parasite relatively common in dogs. Occasional transmission of larvae to humans occurs via an insect bite and development of an immature worm at the bite site. The disease, once confined to southern Europe, is becoming increasingly widespread, particularly due to global warming. Clinical signs are nonspecific and laboratory findings usually normal. Imaging shows pseudotumor features also nonspecific on computed tomography (CT) and magnetic resonance imaging (MRI) scans. Ultrasound may suggest the diagnosis by the presence of double echogenic 'rail' images. However, only spontaneous motility of the parasite observation can confirm the diagnosis.