Dog heartworm

Definition

A filarial nematode, Dirofilaria immitis, that parasitizes the pulmonary arteries and right ventricle of canids and other carnivores, transmitted exclusively by mosquito vectors (Culicidae). The adult worms cause dirofilariasis, a progressive cardiopulmonary disease in definitive hosts; mosquitoes acquire microfilariae during blood-feeding and serve as obligate intermediate hosts where larval development to the infective L3 stage occurs. While dogs are the primary reservoir, infections also occur in wild canids, felids, mustelids, and occasionally humans (aberrant hosts).

Etymology

Example

In regions where Aedes aegypti and Culex pipiens are abundant, veterinary entomologists monitor mosquito infection rates to predict seasonal risk of dog heartworm transmission to unprotected canine populations.

Synonyms

• heartworm
• Dirofilaria immitis

Related Terms

• dirofilariasis
• Filarial worm
• Microfilaria
• Vector-borne disease
• Mosquito
• Definitive host
• Intermediate host
• zoonosis

Usage Notes

The common name 'heartworm' is sometimes used loosely for related filarial parasites (e.g., Dirofilaria repens in subcutaneous tissues), but in veterinary contexts typically refers specifically to D. immitis. The term emphasizes the definitive host rather than taxonomy; specialists use Dirofilaria immitis for precision. In human medicine, infections are termed 'pulmonary dirofilariasis' to distinguish from canine disease.