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.
Many organisms, including some plants, animals, spiders, crustaceans, bacteria, and worms, are considered parasites. Many parasites can enter the human body and cause parasitic infections. Parasites may enter the body through openings in the body, including the skin and mouth. Each type of parasite affects the human body differently. Some feed on humans cells (such as red blood cells), while others live in the intestines and absorb nutrients from food that is consumed by the host.