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Scabies is a skin condition that is very contagious. Scabies is caused by scabies mites, which are tiny parasites with eight legs. The main symptom of scabies is an itchy rash, which is caused by an allergic reaction to the proteins on the mites and in their feces.
Scabies often cause a pimple-like rash which can be severely itchy. Left untreated, itching from scabies becomes progressively worse. Scabies rash typically itches more at night, to the point that it can prevent sleep. People with scabies may scratch so much that they break open their skin which can give access to infection-causing bacteria.
Scabies infection may occur anywhere on the body. Mites are most commonly found between the fingers, on the arms around the wrist, elbow, or armpit, or on the trunk of the body around the penis, nipples, waist, buttocks, or shoulder blades. Young children may also be infected on the head, face, or neck, as well as on the palms of the hands and soles of the feet.
Female scabies mites burrow under the surface of the skin to lay their eggs. This can cause tiny burrow lines or tracks in the skin that may be skin-colored or gray-white. Scabies infection may consist of only 10 to 15 mites, so the burrows may be very difficult to find. Common locations include between the fingers, in the skin folds on the elbow, wrist, or knee, or on the penis, breast, or shoulder blades.
Some people may develop a more severe form of scabies known as crusted scabies. This is most common in the elderly, people who are immunocompromised, and people who cannot itch or scratch such as those who have a loss of sensation, spinal cord injury, or paralysis. Symptoms of crusted scabies include crusted areas on the skin and pockets which can contain up to 2 million mites. People with crusted scabies may not be able to feel the normal itching caused by scabies.
Scabies is a highly contagious condition. Mites are generally transferred directly from skin to skin during prolonged contact such as during sex. A person is able to spread scabies as soon as he is infected, although symptoms can take between two and six weeks to develop.