Human Pulmonary Dirofilariasis,
North Queensland, Australia, 2023

Dirofilaria immitis is a mosquito-borne parasite that primarily causes heartworm disease in dogs but is increasingly reported in human infections. The article describes a case of a 75-year-old man from Townsville, Queensland, diagnosed with human pulmonary dirofilariasis in 2023. The parasite was discovered incidentally during surgery to remove a lung tumor. Parasite larvae migrate through the circulatory system and die in pulmonary blood vessels, leading to granuloma formation. These granulomas appear as round, dense nodules measuring 0.5–4.5 cm and can be mistaken for lung cancer. Human pulmonary dirofilariasis is typically asymptomatic and self-limiting, and specific treatment is generally not necessary. This case highlights the risk of zoonotic transmission in regions with high canine heartworm prevalence.