Scabies is a contagious skin disease caused by a species of mite that is very small.

Scabies is found worldwide among people of all groups and ages. It is spread by direct contact with infected people and less often by sharing clothing or bedding. Sometimes whole families are affected.

The mites that cause scabies burrow into the skin and deposit their eggs, forming a burrow that looks like a pencil mark. Eggs mature in 21 days. The itchy rash is an allergic response to the mite.

• Itching, especially at night
• Rashes
• Sores (abrasions) on the skin from scratching and digging
• Thin, pencil-mark lines on the skin

Mites may be more widespread on a baby's skin, causing pimples over the trunk, or small blisters over the palms and soles. In young children, the head, neck, shoulders, palms, and soles are involved. In older children and adults, the hands, wrists, genitals, and abdomen are involved.

Examination of the skin shows signs of scabies. Tests include an examination under the microscope of skin scrapings taken from a burrow.

Prescription medicated creams are commonly used to treat scabies infections. The most commonly used cream is permethrin 5%. Other creams include benzyl benzoate and sulfur in petrolatum. Lindane is rarely used, because of its side effects.

Creams are applied all over the body. The whole family or sexual partners of infected people may need to be treated, even if they do not have symptoms.

For difficult cases, some health care providers may also prescribe medication taken by mouth to kill the scabies mites. Ivermectin is a pill that may be used.

Itching may continue after treatment begins, but will disappear if you follow your health care provider's prescribed treatment plan. You can reduce itching with cool soaks and calamine lotion. Your doctor may also recommend an oral antihistamine.

Most cases of scabies can be cured without any long-term problems. A severe case with a lot of scaling or crusting may be a sign that the person has a disease such as HIV.

Intense scratching can cause a secondary skin infection, such as impetigo.

Call your health care provider if:

• You have symptoms of scabies
• A person you have been in close contact with has been diagnosed with scabies

Avoid contact with infected persons.

Jacobson CC, Abel EA. Parasitic infestations. J Am Acad Dermatol. 2007;56:1026-1043.