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(Dog Heartworm Infection)


Richard D. Pearson

, MD, University of Virginia School of Medicine

Last full review/revision Sep 2020| Content last modified Sep 2020
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Dirofilariasis is a filarial nematode infection with Dirofilaria immitis, the dog heartworm, or other Dirofilaria species, which are transmitted to humans by infected mosquitoes.

Symptomatic human dirofilariasis is very rare, but larvae may become encapsulated in infarcted lung tissue and produce well-defined pulmonary nodules; rarely, larvae form nodules in the eyes, brain, and/or testes.

Patients may have chest pain, cough, and occasionally hemoptysis. Many patients remain asymptomatic, and a pulmonary nodule, which may suggest a tumor, is discovered during routine chest x-ray.

Dirofilariasis is diagnosed by histologic examination of a surgical specimen.

No anthelmintic treatment is indicated in humans; infection is self-limited.

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