It takes just one bite of an infected mosquito for the heartworm parasite (Dirofilaria immiti) to travel through your pet’s bloodstream and cause a deadly parasitic infection in your pet’s heart.

1. An uninfected mosquito bites a heartworm-positive animal and ingests heartworm larvae (microfilariae) along with their blood.
2. These larvae can take 10 to 28 days to develop inside of the mosquito.
3. Once the larvae reach their infective stage, the mosquito can pass these deadly larvae into the bloodstream of any uninfected dog or cat that they bite.
4. After just one bite from an infective mosquito, the microfilariae begin to migrate through the bloodstream into the animal’s heart.
5. It can take 2-4 months before they reach the heart or lungs, and an additional 2 months for them to develop into adult heartworms.
6. Within 6-7 months after the initial infection, adult female heartworms begin to shed microfilaria into the pet’s bloodstream – and the cycle starts again.