Why don't humans get heart worms?

[Jodocus]

I saw on TV that dogs get heartworms from being bit by mosquitoes. How come humans don’t get heart worms then?

[Desmostylus]

http://www.rci.rutgers.edu/~insects/hartw.htm

Can human beings get the disease?

Although isolated human infections have been reported, dog heartworm is not presently recognized as a human health problem. The parasite, however, is by no means limited to the dog. The fox, wolf, and raccoon have been shown to be reservoirs, and evidence implies that the skunk, muskrat, and opossum may be infected as well. Although the household cat is capable of harboring Dirofilaria immitis, infected cats are rarely found. Evidence suggests that mature heartworm adults maybe rendered sterile in animals other than canines. If this proves to be true, blood tests on household cats would show no microfilarial activity even though the adult worms are present.

[phraser]

In my Epidemiology and Public Health subject, we were told that humans can indeed get heartworm (Dirofilaria immitis), although it’s quite rare.

The lesions are “coin spots” on the lung, which are indistinguishable from tumours on x-ray. Worms aren’t seen in the heart (like in dogs or cats).

The Rutgers cite is somewhat out of date- feline heartworm is a serious (and reasonaby common) disease, although the infectious load of adults is usually lower. Microfilarial disease is seen in cats, according to my parasitology lecturer.