An Overview of Scabies

Show Article Table of Contents

Scabies is a condition caused by Sarcoptes scabiei, a mite. It is characterized by an itchy sensation that may or may not be accompanied by a rash. Scabies affects males and females equally, can be seen in people of all ages, and spreads to individuals of all ethnic groups and in geographic regions throughout the world. In fact, it is estimated that at least 300 million cases of scabies occur worldwide every year. Scabies can be treated and is not typically associated with harmful health problems, although skin infection or scarring can occur as a result of excessive scratching and resulting bacterial infection. 

Symptoms

Leading the list of scabies signs and symptoms is intense itching that starts within days of exposure to the mite, but may begin up to several weeks after. The incubation period, the time between exposure to the mite and the onset of symptoms, is shorter if you have had the infection before.

Itching most commonly affects the underarms, elbows, wrists, fingers, breasts, buttocks, or genitals, and does not usually affect the face. The itching is normally present all the time but is often more noticeable at night.

The itching of scabies may be accompanied by a visible rash that can appear as small red bumps, welts, or scaly lesions. You might develop skin cuts and scratch marks as the result of repeatedly scratching your itchy skin.

Symptoms can be worse if you have an allergic reaction to the mite. Very young children may have more extensive involvement, including the face, head, palms, and soles, while adults do not.

An advanced form of scabies, Norwegian scabies, is characterized by areas of crusting that contain large amounts of mites.

Causes

Scabies is caused by an invasion of the mite into the skin, which occurs when there is direct skin-to-skin contact with someone who has the condition. This can be and often is sexual contact, but other kinds of close and prolonged skin contact are also associated with the spread of scabies (as is often the case in crowded situations). Giving someone a quick hug or a handshake does not usually put you at risk.

The mite does not live for longer than a day or two on inanimate objects, so it is rare to catch scabies by touching things that have come in contact with someone who has or has had scabies. Nevertheless, while it is not common, infested bedding or clothes may cause a new infection.

The parasitic mite is tiny, typically too small to be seen with the naked eye. The female mite burrows under the skin and lays 10 to 25 eggs before she dies. The eggs hatch three days later and the larvae move to the surface of the skin. The larvae mature into adults in 10 to 14 days.

Diagnosis

A doctor's judgment is usually all that is used to diagnose scabies, and he or she will specifically consider the presence of intense itching and the appearance and location of a rash. Perhaps obviously, your rash is more likely to be scabies if you live with someone or have come in contact with someone who has scabies.

The Rash

The rash that scabies causes can often look similar to other rashes. Again, a scabies rash typically occurs on the wrists, in between fingers, in the armpits, around the waist, and in the genital area. While rash in those locations doesn't outright confirm scabies, it is something that certainly raises the prospect of it.

The rash causes red papules with small lines that are attached, called burrows, which essentially trace the path of the mite. Since the mite doesn't usually travel far once it's under the skin, burrows may or may not be visible. The rash may also cause intense inflammation in the skin with blisters, redness, and itching. Scabies photos can give you a good idea of what a scabies rash can look like. 

Diagnostic Tests

There are no good tests that can diagnose scabies, but a doctor might consider scraping off a small portion of the rash and having it examined under a microscope for mites or mite eggs; scaly skin makes for the best samples. Often, however, the mite and the eggs are not visualized, even if a person has scabies.

Some advanced microscopic techniques may improve the sensitivity of diagnosis. 

Treatment

The following treatment options can help get rid of scabies rash.

  • Permethrin 5% cream: Standard first-line therapy for most people, including pregnant or breastfeeding women and children over 2 months old. Apply it liberally from the top of the neck to the soles of the feet at bedtime and rinse it off in the morning. It is important to know that permethrin is the safest treatment for pregnant women.
  • Ivermectin: An alternative therapy but not recommended for children weighing under 33 pounds. This oral medication is used to treat other parasites. The dose used is calculated by your weight, and the medication is taken in two doses, two weeks apart. It is currently not approved by the FDA for the treatment of scabies, but there are studies that show that it is effective, and the Centers for Disease Control (CDC) recommends its use for people who do not improve with treatments for scabies that are FDA approved. 
  • Sulfur ointment (precipitated sulfur): Another safe second-line treatment in pregnant women. It's also used as a first-line treatment for newborns younger than 2 months old. 

    Medications work by killing the mites, but they remain in the skin until the body breaks them down and absorbs them. This process can take about four weeks, and it is common for the scabies rash to be very itchy for that duration. Topical steroids applied to particularly bothersome spots and oral antihistamines, like Benadryl (diphenhydramine Hcl), may help relieve itching.

    Prevention

    As mentioned, the best way to prevent scabies is to avoid close contact with those who have it. That said, many cases of scabies are passed from one person to another before the first individual even knows they have been affected.

    If you have been in close contact with someone who has been diagnosed with scabies, you should also be treated—whether you are showing signs and symptoms of scabies or not. Often, entire households are treated even if only one person has scabies. If your healthcare provider recommends treating your whole family, everyone should receive treatment at the same time. 

    All clothes, bedding, and towels used by the person who has scabies rash should be washed in hot water and dried in a hot dryer. Very high temperature destroys the mite, preventing it from spreading. If you cannot wash certain objects, you can avoid contact and put them in a plastic bag for three days to decontaminate them. The mite can survive for months on a person's body, but only for a few days on objects, which makes efforts to decontaminate items effective if done properly. 

    A Word From Verywell

    If you have scabies, the itching and rash can be intensely uncomfortable. You can recover much faster and more comfortably if you get medical attention as soon as you know that you might have been exposed, or as soon as you begin to experience signs or symptoms of the condition—whichever comes first.

    There can be a stigma associated with scabies, as many are unaware of exactly how it is caused. If this is a concern for you, you may find it helpful to be upfront about your diagnosis with those it may affect, explain the steps you're taking to protect shared spaces, and talk about what you've learned in regard to how easily it can be spread.

    Symptoms of Scabies
    View Article Sources