Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Scabies is a very contagious skin condition that is caused by a mite that is so small it can only be seen with a magnifying glass or under a microscope. The mite cannot live more than three days without a human host, but it can survive up to a month when living on a human. The mite also lays eggs in human skin, which hatch and grow into adult mites. This means that symptoms of the condition can last for months or even years.
The rash caused by bites
from the scabies mite is extremely itchy and is sometimes called "the seven-year itch." The rash can be subtle, and sometimes scabies is hard to diagnose. The mite is spread from person to person by close contact. Animals can harbor a similar mite, but when the animal mite is passed to people, it cannot reproduce and dies within a few days.
Scabies affect everyone regardless of age, gender, race, social class, or personal-hygiene habits. However, a major risk factor is being a household member or sexual partner of an affected individual. Scabies is also common in congested areas, such as nursing homes and hospitals, where it can spread widely. In people who have poor immune systems or who are malnourished, scabies can cause a syndrome called "crusted scabies" or "Norwegian scabies," which causes skin thickening and a scaly rash.
Other conditions are sometimes confused with scabies. The scabies mite has no relation to body lice, although the treatment of the resulting skin disease is sometimes the same. Scabies is also different from
bedbug bites. In contrast to scabies, bedbugs are visible to the naked eye and can live for long periods of time without feeding. Chiggers are a type of mite that can feed off human blood, but unlike scabies, they are acquired through contact with vegetation and feed for only a few days. Less commonly, the rashes of other skin diseases such as
ringworm, shingles, eczema,
allergic reactions (hives), or impetigo may be confused with that of scabies.
Allergic ReactionAn allergic reaction is an overreaction to a harmless substance. Symptoms and signs of an allergic reaction include hives, rashes, swelling, itching, wheezing, ...learn more >>
Hives and AngioedemaHives is a sudden allergic skin reaction. Hives are raised reddish bumps that cause severe itching. Angioedema is similar to hives but the welts are larger and ...learn more >>
RashA rash is a visible skin outbreak. Examples of noninfectious rashes include eczema, psoriasis, contact dermatitis, seborrheic dermatitis, rosacea, hives, and al...learn more >>
Author: Melissa Conrad Stöppler, MD
Editor: Charles Davis, MD, PhD
Scabies occurs when mites of the species Sarcoptes scabiei burrow into the skin,
causing a troubling and relentless itching. The itching may persist for about
two weeks even if all of the mites are killed. If an individual is known to have
scabies and no previous skin-to-skin contact has occurred, prevention can
usually be accomplished by avoiding direct skin contact. It is also advisable to
avoid contact with bedding, clothing, and sometimes even furniture that has been
used by the infested person.
Among young people, skin-to-skin transmission most often occurs during sexual
contact, so scabies can be considered a form of sexually transmitted disease.
However, other forms of close contact such as hugging may spread the disease.
Casual contact such as shaking hands usually will not result in transmission of
the mites.
