D immitis is derived from the Latin words
diro and filum, meaning “evil thread.” Dogs,
cats, foxes, and other mammals are natural hosts, with the mosquito as
the vector-intermediate host, and humans as dead-end hosts. In dogs,
mature adult worms shed microfilariae from the right ventricle into the
blood stream, which are taken up by the mosquito and transferred to
humans during a blood meal in the larval stage. The larvae migrate to
the human venous circulation, die in the right ventricle, embolize into
the pulmonary artery, and organize into a necrotic and fibrotic nodule.
Since man is a dead-end host and not subject to microfilaremia,
treatment is unnecessary.