parasite

A flea is a common parasite that lives on the skin of dogs and cats.

(Chinese) 跳蚤是一种常见的寄生虫，生活在猫狗的皮肤上。

The doctor explained that the stomach pain was caused by an intestinal parasite.

(Chinese) 医生解释说胃痛是由肠道寄生虫引起的。