What is the main transmission route for heartworm larvae?

The primary transmission route for heartworm larvae is through mosquito bites. When a mosquito bites an infected animal, it ingests microfilariae—immature heartworm larvae—present in the animal's bloodstream. The larvae then develop within the mosquito over a span of several weeks. Once they mature, the mosquito becomes capable of transferring these larvae when it subsequently bites another animal, such as a dog or cat. This life cycle highlights the significant role that mosquitoes play in the spread of heartworms, making them essential vectors for the disease.

Contaminated water, direct contact with other infected pets, or contaminated food are not associated with heartworm transmission. Heartworms specifically require a mosquito intermediary to facilitate their transmission from one host to another, which distinguishes their spread from many other parasites that can be transmitted in different ways.