Scabies, also known as the seven-year itch, is a contagious skin infestation by the mite Sarcoptes scabiei. The most common symptoms are severe itchiness and a pimple-like rash.Occasionally, tiny burrows may be seen in the skin. In a first-ever infection a person will usually develop symptoms in between two and six weeks.During a second infection symptoms may begin in as little as 24 hours.These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline.The head may be affected, but this is typically only in young children.The itch is often worse at night.Scratching may cause skin breakdown and an additional bacterial infection of the skin.
Scabies is caused by infection with the female mite Sarcoptes scabiei var. hominis, an ectoparasite.The mites burrow into the skin to live and deposit eggs. The symptoms of scabies are due to an allergic reaction to the mites.Often, only between 10 and 15 mites are involved in an infectionScabies is most often spread during a relatively long period of direct skin contact with an infected person (at least 10 minutes) such as that which may occur during sex or living together.Spread of disease may occur even if the person has not developed symptoms yet.Crowded living conditions, such as those found in child-care facilities, group homes, and prisons, increase the risk of spread.Areas with a lack of access to water also have higher rates of disease.Crusted scabies is a more severe form of the disease. It typically only occurs in those with a poor immune system and people may have millions of mites, making them much more contagious.In these cases, spread of infection may occur during brief contact or by contaminated objects.The mite is very small and usually not directly visible. Diagnosis is based on the signs and symptoms.