The element is a clause if there is a subject and a verb, and it is a phrase if both of these parts of speech are not present. What comes after the introductory element is always an independent clause, or complete sentence, on its own, and the introductory element gives meaning to it.
A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites.
Parasitic worms are a widespread source of infection in humans. Intestinal parasites such as parasitic worms infect more than one-fourth of the world's population, according to the World Health Organization. These infections result in disease, disability and death.Although there are more than 20 different species of parasitic worms that infect humans, almost all of them can be treated with one of five common prescription drugs. Medications are also available for infections of parasites other than worms.arasitic worms are a widespread source of infection in humans. Intestinal parasites such as parasitic worms infect more than one-fourth of the world's population, according to the World Health Organization. These infections result in disease, disability and death.