Canine heartworm (Dirofilaria immitis, Leidy) and risk of infection in human.

Abstract

Canine heartworm (Dirofilaria immitis) is a filarial nematode which dogs, cats and some wildlife creatures are definitive hosts, and humans are accidental hosts. Life cycle of this nematode involves the development in the mosquito vector. Microfilaria released from a female nematode can be found in the definitive host’s blood circulation and is required to develop into the third or infective stage larva in the mosquito. Infective stage larva will be released from infected mosquito’s mouthpart into the host’s skin during the course of taking the blood meal, develop into an adult stage in the definitive host, and reside in the right ventricle and pulmonary artery. It will, however, decease in humans which are the accidental host. Because of the inflammation and immune response in humans, granuloma will be formed around the dead nematode larva and usually found under the skin or in the lung. Lung granuloma sometimes might be occasionally found during the chest x-ray; however, it is difficult to differentiate from the lesions caused by fungi, bacteria and tumor. People who live near infected dogs should be concerned with the risk of infection as well as preventing themselves from this zoonosis.