Hundreds of human parasites exist and can affect any area on the human body. Parasitic infection occurs in any age group, but young children are most susceptible because of risky hand-to-mouth behaviors. A parasite is an organism living on or in its host, obtaining nourishment from the host. It is considered an infestation when the parasite overruns the host in numbers large enough to be harmful.
Ectoparasites
A parasite living on the outer surface of its host is considered an ectoparasite, usually living on or in the skin. Some mites happily coexist with humans, such as face mites called demodex, while others, chiggers and scabies, cause intense itching from their biting or burrowing into the skin. Lice live in skin pores and hair follicles. Lice and most mites are spread by close human contact. Ticks spread by grasping onto a host from tall grass in wooded areas, then burrowing their heads into the skin to feed on blood. Medications remove mites and lice, while tick removal is accomplished with tweezers.
Protozoa
Protozoa are single-celled organisms that divide within the host. The classification covers invaders such as giardia, cryptosporidium, toxoplasmosis and malaria. Intestinal protozoa, such as giardia or cryptosporidium, transmit by the fecal-oral route, whereas protozoa living in blood or tissues, malaria, are transmitted by an arthropod. Cryptosporidium outbreaks are common in day care centers. Detection is accomplished by microscopy, antibody detection or RNA detection, depending on the organism. Preventive techniques include sanitary methods and water filtration. Certain antibiotics treat protozoan infections, while some infections don't have any treatment.
Worms
Many kinds of worms have the ability to infect humans. Hookworm, roundworm and pinworm are some of the most common. About 14 percent of the U.S. population is infected with dog and cat roundworms called toxocara. Children pick up many types of worms from contaminated soil. Consumed tapeworm eggs hatch in the intestine, migrate to the lungs and get coughed up and re-swallowed to infest the intestine as adults. Eggs expelled in feces re-contaminate the environment. Some serious effects of parasitic worms include anemia, blindness and bowel obstruction. Prescribed medications eliminate worms.
Flukes
A fluke is a parasitic flatworm. Flukes inhabit the digestive system or the liver. Some might migrate into the heart, brain or skin. Infections are usually acquired by children drinking infected water, eating aquatic vegetation or raw meat. Chronic diarrhea and abdominal pain occur as symptoms. Fecal exams detect eggs but egg numbers vary. Therefore, repeated fecal exams might be needed. Flukes can be killed by thoroughly cooking meats and vegetables from suspected waters and several medications are available to treat an infestation.
Fungus
Fungi live on human skin as ringworm, athlete's foot and jock itch. Fungal infections appear on the body after contact with contaminated objects or infected persons. Locker rooms and showers spread fungus to young athletes. Body areas experiencing high heat and perspiration develop fungus most often. Skin may crack, blister and peel. Ringworm causes round itchy patches, which can infect fingernails because of scratching. Over-the-counter medications kill parasitic fungi.
