Final answer:
The helminth parasites in question are hookworms and whipworms, both within the roundworm category. They infect humans and complete their life cycle within the host, with eggs being excreted in feces. Generally, they cannot be visually detected in the feces without a microscope.
Step-by-step explanation:
Understanding GI Parasites: Hookworms and Whipworms
Helminths are multicellular organisms known as parasitic worms, and they infect animals including humans. These parasites are categorized into two major groups, the roundworms (Nematoda) and the flatworms (Platyhelminthes). Among the roundworms, one can find parasites such as hookworms, whipworms, and pinworms.
Hookworms are nematodes that infect the human intestine. They use their 'hooks' to grab onto the host's tissue. Hookworm larvae enter through the skin and then travel to the intestine. Similarly, another group of nematodes is whipworms, specifically Trichuris trichiura, which cause trichuriasis. They are transmitted by ingesting soil-contaminated matter. Both hookworms and whipworms lay eggs which are excreted in feces, continuing their life cycle. Despite their significant presence in humans, they often do not cause obvious disease and can't be seen in the feces upon gross examination.