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.
A lice infestation is a population of small parasites that live on the human body. There are three types of lice: head lice, body lice, and pubic lice (or crab lice). All three forms are passed on through skin-to-skin contact and can spread quickly. Body lice can carry diseases, but head lice and pubic lice cannot.ice infestations are classified by the body part they correspond to. Different lice are attracted to different parts of the body. The head louse attaches to hair on the head and lays eggs at the base of a strand.