What are heartworms?
Heartworms are roundworms that, as the name suggests, live in the heart and also the lungs of mammals. But this is only at two stages of their lifecyde. Heartworms begin their life in the pulmonary (lung) arteries of a mammal, typically a dog, as microfilaria (“little worms”, the LI stage) and quickly make their way into the circulatory system of their host. A mosquito takes a bloodmeal from this infected animal ingesting microfilaria at the same time. In the dog, microfilaria not ingested by a mosquito will, over a 2-3 year period, die; they will not mature past this stage of life. In the mosquito the microfilaria go through two molts, into the larval (L3) stage, and then migrate to the mouthparts of the mosquito. The mosquito takes a bloodmeal, depositing the larvae onto the animal. The larvae make their way into the bite wound left by the mosquito and into the tissue of the animal. Over the next 190 days the larvae go through two more molts, becoming immature adults, the L5 stage, a
