Parasites are organisms that get their nutrients and shelter by feeding on other organisms. In the case of human skin parasites, the tiny creatures scavenge on skin cells and blood. Some tunnel and burrow into the skin, while others find a meal, or a home, on the skin's surface. Several common types of skin parasites cause only annoyance and itching, but others can transmit serious diseases.
Scabies
Sarcoptes scabei is a parasite that is found worldwide and causes more than 300 million cases of scabies each year, according to the American Academy of Dermatology. It is spread easily, particularly in crowded conditions. People can get scabies from clothing and bedding, but skin-to-skin contact is the main route of transmission. Once on the skin, the impregnated females begin to cut and burrow into the upper layers of skin, laying their eggs as they go. This burrowing creates small raised lines on the skin. The most common sites of infestation are the webs between the fingers, wrists, knees and elbows. Scabies also is known as the itch mite, it's main symptom being severe itching, especially at night.
Head Lice
Head lice, also known as pediculosis, is caused by the parasite Pediculus humanus capitis. The Centers for Disease Control and Prevention, or CDC, describes head lice as blood hungry organisms that live on the scalp and feed several times each day. Head lice is very common and very contagious. Children ages 3 to 11 are most frequently infested. The adult louse is tan or gray in color and is about the size of a sesame seed. They lay their eggs, called nits, at the base of the hair shaft, close to the scalp. Head lice are usually transmitted by head-to-head contact, but can be spread through contaminated bedding, carpet, hair brushes or articles of clothing. Symptoms of head lice infestation can range from none to severe itching, especially at the neck line on the back of the head.
Pubic Lice
Phthirus pubis, also known as pubic lice or "crabs," are usually spread through sexual contact. Transmission also can occur through infested clothing and bedding. The lice spend their time in the hairs of the pubic and anal areas. Sometimes they can spread to the thighs, facial hair or the trunk of the body. Many people with pubic lice have no symptoms, while others experience itching and may have swollen lymph nodes, according to Merck Manuals Medical Library.
Ticks
Ticks are parasites that feed on blood. They can spread serious illnesses, including Rocky mountain spotted fever, tularemia and Lyme disease. Tick-borne disease is a health concern in all major regions of the world, excluding Antarctica, reports the CDC. People bitten by ticks usually are not aware of it. After the tick falls off there may be a red spot, or some itching. If a tick is found on the skin it should be removed as soon as possible to decrease the risk of disease transmission.
