Q: My granddaughter Kyara would like to know why dogs and some cats get heartworms and humans do not?
A: Dogs are the definitive host for heartworm disease. This means that heartworms are able to complete their lifecycle (mature into adults and reproduce) in the dog’s body. Mosquitoes are required for transmission from one dog to another; they are called “intermediate hosts.” Heartworm infection occurs primarily in dogs, but the incidence of heartworm infection in cats is increasing. Although extremely rare, it is possible for humans to be infected with heartworms from a mosquito bite. Since humans are not natural hosts of heartworms, the heartworm larvae cannot develop into adult worms and they die. Heartworm disease has become less prevalent in dogs in this area of the country thanks to the large scale use of preventatives, so the risk for human infection is extremely low. It is important to administer monthly heartworm preventative to your pets to limit their risk of heartworm infection as well as the potential for your pet to act as a reservoir for the disease.