Scabies is an itchy skin condition caused by a tiny burrowing mite called Sarcoptes scabiei. Intense itching occurs in the area where the mite burrows. The urge to scratch may be especially strong at night.
Scabies is contagious and can spread quickly through close physical contact in a family, child care group, school class, nursing home or prison. Because scabies is so contagious, doctors often recommend treatment for entire families or contact groups.
Scabies can be readily treated. Medications applied to your skin kill the mites that cause scabies and their eggs. But you may still have some itching for several weeks after treatment.
Symptoms:
Scabies signs and symptoms include:
- Itching, often severe and usually worse at night
- Thin, irregular burrow tracks made up of tiny blisters or bumps on your skin
The burrows or tracks typically appear in folds of skin. Though almost any part of the body may be involved, in adults and older children scabies is most often found:
- Between the fingers
- In the armpits
- Around the waist
- Along the insides of the wrists
- On the inner elbows
- On the soles of the feet
- Around the breasts
- Around the male genital area
- On the buttocks
- On the knees
In infants and young children, common sites of infestation usually include the:
- Scalp
- Palms of the hands
- Soles of the feet
If you've had scabies before, signs and symptoms may develop within a few days of exposure. If you've never had scabies, it can take as long as six weeks for signs and symptoms to begin. You can still spread scabies even if you don't have any signs or symptoms yet.
Causes
The eight-legged mite that causes scabies in humans is microscopic. The female mite burrows just beneath your skin and makes a tunnel where it deposits eggs.
The eggs hatch, and the mite larvae work their way to the surface of your skin, where they mature and can spread to other areas of your skin or to the skin of other people. The itching of scabies results from your body's allergic reaction to the mites, their eggs and their waste.
Close physical contact and, less often, the sharing of clothing or bedding with an infected person can spread the mites.
Animals and humans all are affected by their own distinct species of mites. Each species prefers one specific type of host and doesn't live long away from that preferred host.
Humans may have a temporary skin reaction from contact with the animal scabies mite. But people are unlikely to develop full-blown scabies from this source, as they might from contact with the human scabies mite.
Diagnosis
To diagnose scabies, your doctor examines your skin, looking for signs of mites, including the characteristic burrows. When your doctor locates a mite burrow, he or she may take a scraping from that area of your skin to examine under a microscope. The microscopic examination can determine the presence of mites or their eggs.
Treatment
Scabies treatment involves eliminating the infestation with medications. Several creams and lotions are available with a doctor's prescription.
Your doctor will likely ask you to apply the medication to your whole body, from the neck down, and leave the medication on for at least eight to 10 hours. Some treatments require a second application, and treatments need to be repeated if new burrows and a rash appear.
Because scabies spreads so easily, your doctor will likely recommend treatment for all household members and other close contacts, even if they show no signs of scabies infestation.
Medications commonly prescribed for scabies include:
- Permethrin cream (Elimite). Permethrin is a topical cream that contains chemicals that kill scabies mites and their eggs. It is generally considered safe for adults, pregnant women, and children ages 2 months and older.
- Lindane lotion. This medication — also a chemical treatment — is recommended only for people who can't tolerate other approved treatments or for whom other treatments didn't work. This medication isn't safe for children younger than age 10 years, women who are pregnant or nursing, or anyone who weighs less than 110 pounds (50 kilograms).
- Crotamiton (Eurax). This medication is available as a cream or a lotion. It's applied once a day for two days. The safety of this medication hasn't been established in children, adults 65 and older, or women who are pregnant or nursing. Frequent treatment failure has been reported with crotamiton.
- Ivermectin (Stromectol). Doctors may prescribe this oral medication for people with altered immune systems, for people who have crusted scabies, or for people who don't respond to the prescription lotions and creams. Ivermectin isn't recommended for women who are pregnant or nursing, or for children who weigh less than 33 pounds (15 kilograms).
Although these medications kill the mites promptly, you may find that the itching doesn't stop entirely for several weeks.
Doctors may prescribe other topical medications, such as sulfur compounded in petrolatum, for people who don't respond to or can't use these medications.
