Zoology 10th Edition by Stephen Miller,John Harley

Exercise 11

In parasitism one organism lives in or on another known as the host. Definitive hosts harbor the sexual stage of the protozoan. Intermediate hosts harbor the asexually reproducing stages of the protozoan. In commensalism, one member benefits while the other is neither harmed nor is benefited. In mutualism, both species benefit.
Control strategies for combating parasitic protists often target intermediate host organisms. Why are these strategies effective?