Heartworm Disease is caused by a roundworm (nematode) parasite called Dirofilaria immitus, which is carried by mosquitoes. It is more common in warm, humid areas but can be seen anywhere, especially as animals are often moved around geographically.

Life Cycle

Animals cannot directly infect each other with heartworm. (A mosquito is the go-between.)

 
©Copyright 2007 | American Heartworm Society

The life cycle is as follows:

1. Female worms in an infected animal lay eggs which hatch into early larvae (microfilaria) in the bloodstream.
2. A mosquito bites the animal and drinks the microfilaria with the blood.
3. The microfilaria become mature larvae within the mosquito.
4. When the mosquito bites the next animal, these larvae are injected into the body. The larvae mature further within the bloodstream, and as adults they settle into the heart and the pulmonary vessels (the arteries and veins that carry blood between the heart and lungs).
5. The adult worms can then mate and lay eggs, continuing the cycle.

 

To continue reading, please visit DogHealth.com