While not fatal, human worms can be quite disgusting and they can wreak havoc on the human body from the skin to the intestines to the respiratory system. Human worms (parasites) are not uncommon either. In fact, it is believed that at any given time the human body may be infected with dozens of different types of parasites. Some are microscopic while others are visible to the naked eye. Some types of worms can be found most often in animals, for example, the bloodworm typically infects horses, and others may affect humans more often.

At any given time, the human body may be infected with dozens of different types of parasites, such as worms. Some parasites are microscopic while other worms in humans are quite visible to the naked eye. Certain types of parasites are found more often in animals; for example, the bloodworm typically infects horses. Other types of parasites may affect humans more often. In all, there are more than 3,200 types of parasites in existence today and they are divided into the following categories: Cestoda, Nematoda, Protozoa, and Trematoda.