Dirofilaria is a genus of parasitic worms, primarily known for causing heartworm disease in dogs and other animals. The most common species, Dirofilaria immitis, is transmitted through the bites of infected mosquitoes. Once inside the host, the larvae mature into adult worms, which can live in the heart and pulmonary arteries, leading to serious health issues. In addition to dogs, Dirofilaria can also infect cats and other mammals, although the disease is less common in these animals. Prevention typically involves administering monthly medications to pets, which help eliminate any larvae before they can develop into adult worms.