Final answer:
Heartworms, which are parasitic roundworms, primarily infect pets but can also be considered as potential endoparasites in humans. Hookworms and pinworms are other examples of roundworms that commonly affect humans with varying life cycles and health impacts.
Step-by-step explanation:
Heartworms are a type of parasitic roundworm, specifically Dirofilaria, which are well-known for infecting pets such as cats and dogs. In pets, these worms reside in the heart and blood vessels, causing serious diseases. While heartworms are not typical parasites in humans, the concept of parasitism in humans is quite common. Human-specific parasites like hookworms and pinworms have different life cycles and affect their hosts in various ways. Heartworms would be classified as endoparasites if they were to infect a human because they live inside their host. Prevention and treatment are available for pets, which are essential for maintaining their health. In comparison, other roundworms such as those causing elephantiasis have a marked impact on human health and are transmissible through vectors like deerflies. Their life cycle involves growth within the human body and can lead to severe physical manifestations.