Question

Roundworm parasites identified as Trichinella spiralis and Necator americanus can both use humans as their definitive hosts. In both cases, the adult parasites live in the intestine. How do these parasites differ in terms of how their larvae reach a new host?

a) Through ingestion of contaminated meat; penetration through the skin.
b) Through contact with bodily fluids; inhalation of larvae.
c) Through contaminated water; transmission by vectors.
d) Through ingestion of larvae; direct penetration through the skin.

Answer 1

Trichinella spiralis is transmitted to new hosts by the ingestion of contaminated meat, while Necator americanus larvae penetrate through the skin to infect a new host.

Step-by-step explanation:

The roundworm parasites Trichinella spiralis and Necator americanus both use humans as their definitive hosts. Despite their similarity in habitat within the host's intestine, their transmission routes to reach new hosts differ. For Trichinella spiralis, which causes trichinosis, the route of transmission is through the ingestion of contaminated meat, typically undercooked pork, containing the larvae. The larvae are released from cysts when exposed to the stomach's digestive juices, mature into adults in the intestines, and can migrate to muscle tissue to form new cysts. On the other hand, hookworms such as Necator americanus do not rely on ingestion. Their larvae penetrate through the skin, typically through the feet, before making their way to the intestines to mature into adults. Both parasites have complex life cycles and are examples of parasitic nematodes that can cause significant health issues in humans.