Man's best friend: How humans can develop Dirofilaria immitis infections

Abstract

Canine heartworm, Dirofilaria immitis, is a nematode parasite that infects dogs by way of mosquito bite. Rarely, humans play accidental hosts to this parasite and are not a suitable environment for the nematode to live. As the parasite dies in the pulmonary vessels it embolizes the vessels causing infarction and eventual nodule formation in the lungs. In the right clinical context, a nodule can be considered malignant prompting invasive tissue sampling. We describe a case of a 48-year-old man who was found to have multiple asymptomatic scattered pulmonary nodules during imaging workup for an insulinoma. Fine needle biopsy of the largest nodule revealed a necrotic granuloma, lab testing and culture ruled out fungal and bacterial causes. Clinically, this picture was consistent with D. immitis infection.

The Complexity of Zoonotic Filariasis Episystem and Its Consequences: A Multidisciplinary View

“…In the Americas 175 cases of pulmonary infection in humans have been approximately reported, located in the USA (119 cases) [ 6 , 88 , 89 ] and Brazil (close to 50 cases) [ 6 , 90 ], with sporadic reports in Costa Rica, Colombia, Venezuela, and Argentina [ 6 ] ( Figure 3(b) ). Only 34 cases of subcutaneous/ocular infection have been registered, of which 30 are from the USA and Canada, caused by D. tenuis [ 6 , 91 , 92 ], D. ursi or D. subdermata [ 6 , 93 , 94 ], D. striata [ 95 ], Dirofilaria spp.…”

Zoonotic Helminth Diseases in Dogs and Dingoes Utilising Shared Resources in an Australian Aboriginal Community

“…Heartworm is spread by mosquito vectors and is a potentially life-threatening disease for canines. Although infection in humans is generally asymptomatic, the parasite can cause infarction and nodule formation in the lungs [15,16].…”

Subcutaneous parasitic infection in Slovenia: a case report

“…Dirofilaria infections occur more commonly in adults 40 to 49 years old. There are no serologic tests available for Dirofilaria repens, and so microscopic examination of the worm remains the most frequently used diagnostic method, despite a large number of zoonotic Dirofilaria species having morphology similar to Dirofilaria repens, thereby making definitive diagnosis difficult (14,16).…”