Scabies is a contagious skin disease caused by an insect that literally gets under the skin. It is caused by a parasitic mite that burrows under the skin of humans where it feeds and lays eggs. The mite responsible for this condition is called Sarcoptes scabiei and belongs to the arachnid family, to which spiders, ticks and scorpions also belong. Scabies is similar to mange, a skin disorder which affects dogs.
An extremely itchy, pimple-like rash on the skin is a main symptom of scabies. A person with the disease may have visible but small inflamed blisters. He or she may even be able to see the burrows, though they are far less numerous than the mites themselves. Sometimes, scabies causes the skin to ooze and scab, and because of intense itching and scratching, a secondary infection may occur. The mite that causes it is extremely small and invisible to the naked eye, only to be seen with a magnifying glass or microscope. Because the mites are so tiny, the condition is often misdiagnosed as a different kind of rash.
Scabies most commonly affects the hands, wrists and forearms. The mites prefer to dwell in folds of skin such as between the fingers and creases in the arms. The mites also like to congregate in other areas of the body, such as the genitals, waist and breasts. Fortunately, scabies vary rarely affects the face, though it is possible for it to occur anywhere on the body.
This disease usually spreads from skin-to-skin contact. However, it is also spread through sheets, clothing and other materials that are in close contact with an infected body. Members of a household and crowded areas where people are together for an extended period of time, such as schools, shelters and nursing homes, create the ideal environment for scabies to spread. A person may be infected with the mites for more than a month before symptoms occur, though they are still able to transmit them to others.
The symptoms of scabies are caused by an allergic reaction to the eggs and waste of the mites. In a healthy person, the reaction is the body's way of developing antibodies and subsequently killing some of the mites. For those with compromised immune systems, the body is unable to protect itself and the infestation may worsen.
Medical treatment usually involves topical medications in the form of lotions such as permethrin and lindane, though these are only for adults. These lotions are applied liberally from the neck down on a person infected with the mites. Other drugs, though still in the experimental phase, can be taken orally in a single dose. Scabies mites can remain alive without a host for about a week, so it is important to wash all linen and clothing that an infected person has had contact with to prevent re-infestation.