What bodily systems are affected by antiparasitic drugs prescribed for local effects?

Antiparasitic drugs that are prescribed for local effects primarily target specific areas in the body where parasites are present, most commonly the gastrointestinal (GI) tract and the skin. The GI tract is a key area of focus because many parasites, such as worms and protozoa, inhabit this region. Anthelmintics are designed to eliminate these parasites effectively while minimizing systemic effects.

Additionally, certain antiparasitic medications may also be used to treat conditions affecting the skin, such as those caused by ectoparasites like scabies or lice. In these cases, these medications are applied topically to the skin to achieve a localized effect where the parasites are present, leading to their eradication.

The other systems mentioned in the options do not typically relate to the primary action of antiparasitic drugs focusing on local intervention. Therefore, the gastrointestinal tract and skin are the correct bodily systems affected by these medications, emphasizing their role in targeting parasites effectively in confined areas.