Changes

[[Image:dirofilariasis 2.jpg|right|thumb|125px|<small><center>'''Dirofilariasis'''. Courtesy of T. Scase</center></small>]]

[[Image:dirofilariasis 2.jpg|right|thumb|125px|<small><center>'''Dirofilariasis'''. Courtesy of T. Scase</center></small>]]

Heartworm (HW) infection is caused by a filarial organism, Dirofilaria  immitis  . At least 70 species of mosquitos can serve as intermediate hosts; Aedes , Anopheles  , and Culex are the most common genera acting as vectors. Patent infections are possible in numerous wild and companion animal species. Wild animal reservoirs include wolves, coyotes, foxes, California gray seals, sea lions, and raccoons. In companion animals, HW infection is seen primarily in dogs and less commonly in cats and ferrets. HW disease has been reported in most countries with temperate, semitropical, or tropical climates, including the USA, Canada, and southern Europe. In companion animals, infection risk is greatest in dogs and cats housed outdoors. Although any dog, indoor or outdoor, is capable of being infected, most infections are diagnosed in medium- to large-sized, 3- to 8-yr-old dogs.

Dirofilaria immitis is a nematode parasite that causes heartworm disease in dogs and, less commonly, cats and ferrets. Heartworm

disease is transmitted by mosquito bites and there are more than 70 species of mosquito that are able to transmit infection; Aedes, AnopheleS, and Culex are the most common vector species.

 

HW disease has been reported in most countries with temperate, semitropical, or tropical climates, including the USA, Canada, and southern Europe. In companion animals, infection risk is greatest in dogs and cats housed outdoors. Although any dog, indoor or outdoor, is capable of being infected, most infections are diagnosed in medium- to large-sized, 3- to 8-yr-old dogs.

Infected mosquitos are capable of transmitting HW infections to humans, but there are no reports of such infections becoming patent. Maturation of the infective larvae may progress to the point where they reach the lungs, become encapsulated, and die. The dead larvae precipitate granulomatous reactions called “coin lesions,” which are medically significant because radiographically they appear similar to metastatic lung cancer.

Infected mosquitos are capable of transmitting HW infections to humans, but there are no reports of such infections becoming patent. Maturation of the infective larvae may progress to the point where they reach the lungs, become encapsulated, and die. The dead larvae precipitate granulomatous reactions called “coin lesions,” which are medically significant because radiographically they appear similar to metastatic lung cancer.

HW infection rates in other companion animals such as ferrets and cats tend to parallel those in dogs in the same geographic region, but usually at a lower prevalence. No age predilection has been reported in ferrets or cats, but male cats have been reported to be more susceptible than females. Indoor and outdoor ferrets and cats can be infected. Other infections in cats, such as those caused by the feline leukemia virus or feline immunodeficiency virus, are not predisposing factors.

HW infection rates in other companion animals such as ferrets and cats tend to parallel those in dogs in the same geographic region, but usually at a lower prevalence. No age predilection has been reported in ferrets or cats, but male cats have been reported to be more susceptible than females. Indoor and outdoor ferrets and cats can be infected. Other infections in cats, such as those caused by the feline leukemia virus or feline immunodeficiency virus, are not predisposing factors.