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Scabies (cont.)

How Long Do Scabies Live Without a Human Host?

The mite can only survive for three days in the environment. Once on a human body, the mite may reproduce; if the infection remains untreated, it can cause symptoms for years.

Where Does Scabies Come From?

Scabies is spread (transmitted) through skin-to-skin contact with a person who carries the mite. The mites often begin to cause symptoms first at the site where they enter the body. Thus, skin transmission during sexual intercourse may cause skin lesions on the penis, vaginal area, or groin. It is important to point out that scabies is not always a sexually transmitted disease (STD) and may be acquired through any skin-to-skin contact. However, in young, sexually active individuals, scabies is usually spread by sexual contact.

Less commonly, scabies infestation can happen through the sharing of clothes and bedding. Theoretically, a person can get scabies from touching something that the mite is on, but that is not a major mode of transmission. The mite only lives for two to three days away from human skin. Human scabies is not spread by contact with animals or pets; however, the human mites may infest pets like dogs and cats and cause itching; the human mites do not multiply on pets and quickly die. The mites that cause sarcoptic mange, or dog or pet scabies, only multiply on pets like dogs and cats; although they may cause itching on humans, they do not multiply on humans and soon die.

What Are Scabies Symptoms and Signs? What Do Scabies Skin Lesions Look Like?

Symptoms occur from two to six weeks to appear after exposure. They include severe and continuous itching, especially at night.

  • The skin may show signs of small insect-type bites, or the lesions may look like pimples, bumps, or blisters, especially around the wrist, elbow, knee, underarm area, groin, or finger webs. The skin may also have redness, rash, or have sores (welts, bumps or nodules, especially in children, termed nodular scabies) due to scratching of the area. Large nodules of 2-20 mm in diameter may appear in infants unable to scratch.
  • A burrow (a short S-shaped track that indicates the mite's movement under the skin) may also be visible, especially in the webs of fingers and toes. Burrows may be small enough to be overlooked. Thus, scabies also should be considered whenever there is intense itching and/or scratching, even without an obvious rash, bite, or burrow. Ulcers are not frequently formed.
  • Scabies frequently occur in the crevasses of the body such as between the fingers and toes, the buttocks, the elbows, the waist area, the genital area, and under the breasts in women. The face, neck, head, scalp, palms, soles of the feet, and lips are usually not affected, except in infants or very young children.
  • Risk factors such as immune suppression or old age may predispose patients to more extensive disease. In crusted (Norwegian) scabies, the body of the infested person is covered with a thick, dry, and scaly rash. The rash of crusted scabies may or may not itch, but it contains thousands to millions of mites. Crusted scabies is the most contagious form of scabies and the hardest to treat.
  • Many other skin rashes may look like scabies, including allergic drug reactions, contact dermatitis, and viral rashes such as shingles.
Last Reviewed 8/30/2017

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Scabies »

Human scabies is an intensely pruritic skin infestation caused by the host-specific mite, Sarcoptes scabiei var hominis.

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