Nature
Human parasites are the cause of many diseases. There are ectoparasites, like mites and lice, which live on the outside of the body, and internal parasites, which live in the intestinal tract and internal organs. External parasites are generally found on or in the skin and are important pests because they bite or annoy both humans and their pets. Fleas, mange mites, and ticks are the most frequently encountered and most troublesome pests that attack humans and their pets.