Final answer:
Toxocara canis, Toxocara cati, and Toxascaris leonina are ascarids that infect dogs and cats. They are part of a group of organisms that include the Toxoplasma gondii, which causes toxoplasmosis.
Step-by-step explanation:
Toxocara canis, Toxocara cati, and Toxascaris leonina are ascarids that primarily affect domestic animals, specifically dogs and cats. Toxocara canis are typically found in dogs, while Toxocara cati are more commonly associated with cats. Toxascaris leonina can infect both dogs and cats. These parasites are part of the group of organisms called apicomplexans, which include other medically important parasites such as Toxoplasma gondii, responsible for toxoplasmosis. It's important for individuals, especially those who are immunocompromised or pregnant, to be aware of these parasites as they can cause serious health issues.