Final answer:
A pediculus humanus capitis infection is an infection caused by head lice.
Step-by-step explanation:
The medical assistant should explain that pediculus humanus capitis is an infection of a multicellular parasite known as the head louse. Head lice infest hair, laying their eggs at the base of hair fibers. They are one of the three types of lice associated with humans, along with the body louse and the pubic louse. By understanding the different types of lice and their variations, scientists have been able to gather information about human evolution and migration.