Cetaphil Skin Cleanser may be effective, nontoxic treatment for head lice. It works by suffocating the lice.

Human parasites live in or on our bodies and take their nourishment from us. By definition, parasites cannot live on their own--they use us as their hosts. A variety of insects, worms and single-celled organisms cause parasitic infections, which number in the millions annually in the U.S.

Intestinal worms are parasites, or organisms that depend upon other organisms for existence. Although many consider intestinal worms to be a problem affecting poverty-stricken people in poor countries, they are also a health problem in the United States.

Ringworm is a fungal infection that occurs on the skin. The name comes from the ring-like appearance that appears. Ringworm is easily transmitted between people, and it can also be acquired from pets as well. It can occur on any part of the body, including the scalp.

Head lice when left untreated multiply and spread when the lice fall on furniture, bedding and clothing. Lice also transfer through ordinary physical contact, including hugging.

Intestinal worms are parasites, deriving their nutrition from the human gut. Three types of worms can infest the human intestine: roundworms, tapeworms and flukes. The various species within these groups can live in different parts of the intestines, causing differing symptom patterns.

Parasitic nematodes (worms) in humans can be found in the intestines, muscles and other tissues. More people around the world have a nematode infection than any other parasitic infection.

Human intestinal parasites are those that host themselves in the intestinal tract of the human body. According to the University of Maryland Medical Center, there are two types of intestinal parasites.

Roundworms are long, round parasites that may infect humans and cause health problems. Most often, people ingest roundworm larvae or eggs after touching soil, although they may enter directly through the skin, according to the National Institute of Allergy and Infectious Diseases.

Intestinal parasites and worms spend at least a part of their life cycles in the gastrointestinal tracts of host organisms. Intestinal parasites common in the U.S. include roundworms, tapeworms, hookworms and Giardia, a type of protozoa.

Intestinal parasites infect and reside your gastrointestinal tract. You can become infected with two types of intestinal parasites--protozoa and heleminths. Protozoa are microscopic parasites, where as heleminths are worms that are visible to naked eye in their adult stages.

Ascaris lumbricoides, also known as the giant intestinal roundworm, is one of several soil-transmitted nematodes that are infectious to humans. According to the Global Network for Neglected Tropical Diseases, ascariasis is the most common human worm infection. More than 60,000 people die from the disease annually.