Skin Parasites

Skin parasites (PAIR-uh-sites) are tiny organisms that invade the skin, often causing irritation and itching.

What Are Skin Parasites?

Parasites live off other living beings (including people), often feeding and reproducing on them. Some parasites thrive on human blood and cannot live long without it. Parasites may lay their eggs on people's skin. Before long, that person could become the host (an organism that provides another organism, such as a parasite or virus, with a place to live and grow) for hundreds or more of the parasites. 

Skin parasites are found worldwide and infest large numbers of people. For example, as many as 6 to 12 million people worldwide contract head lice every year, according to the Centers for Disease Control and Prevention. Head lice most often affect children in school and daycare settings.

What Are Some Common Skin Parasites?

There are many parasites that infest human skin, but lice, scabies (SKAY-beez), and chiggers are among the most common.

Head lice: 

Also known as Pediculus bumanus capitis (pech-DIH-kyoo-lus HYOO-mah-nus KAH-pih-tis), head lice are six-legged parasites with tiny claws that cling to hairs. They are found on the scalp, neck, and behind the cars. Lice lay visible, whitish eggs called nits. In about seven days, the nits hatch into young called nymphs (NIMFS). Nymphs grow up fast, and in just one week they have matured into adult lice that must feed on blood to stay alive. Head lice may not cause any symptoms immediately, but as with other insect bites, the body reacts to the invaders, leading to itching and sores from scratching.

Pubic lice:

Pubic lice, or Phtbirus pubis (THEER-us PYOO-bus), invade the pubic hair and sometimes other body hair such as beards, cyebrows, eyelashes, and armpit hair. They often are called "crabs" because of their crab-like appearance. Pubic lice cause intense itching, especially at night, when they feed by burying their heads into hair follicles. The nits or adult lice can be seen on pubic hairs or surrounding skin.

Scabies:

Microscopic Sarcoptes scabiei (sar-KOP-teez SKAY-be-eye) mites cause an infestation called scabies. The mites work their way under the top layer of skin and lay their eggs. Most people are not even aware of the intruders until intense itching begins two to six weeks later. Red, pimple-like bumps appear on the skin, and there may be wavy lines on the skin tracing the mites' paths, especially in the webbing between the fingers and in the skin folds at the back of the knees and the inside of the elbows.

Chiggers:

Chiggers are mites that tend to live in weeds, tall grass, or wooded areas. The chigger larvae (LAR-vee, immature mites) feed on a variety of animals, including humans. The larvae crawl onto the skin of passersby and can use their tiny claws to grab onto human hair. They then attach to the skin, usually at the ankles or waist or in skin folds, with hooked mouthparts and feed on skin cells. Unlike lice and scabies, chiggers only feed on their host for a couple of days, then let go and fall off.

Chigger bites can cause a red bump that continues to grow in size, a skin rash, hives, and severe itchiness. Sometimes the larvae are visible in the center of the bump.