What is scabies?
Scabies is a contagious, itchy skin disease caused by an infestation of Sarcoptes scabiei, a microscopic mite that burrows under the skin. Scabies is characterized by intense itching caused by a skin reaction to the mites. Itching most often occurs at night and may be accompanied by pimple-like irritations or rashes, and sores caused by scratching.
Scabies is a common disease that can affect any gender, race, age group, or social background. More than 300 million scabies cases occur globally every year, according to the American Osteopathic College of Dermatology (Source: AOCD).
Scabies spreads through skin-to-skin contact with an infected person. Transmission commonly occurs between family members and sexual partners. Scabies is a major problem in crowded areas, particularly in hospitals, child care centers, prisons, and nursing homes. In some cases, scabies is transmitted by sharing unwashed clothes, towels and bedding. Your pets are not able to spread human scabies, but they can be affected by a different mite infection called mange.
It’s important to know that even people with good personal hygiene can catch scabies. Fortunately, effective medications called scabicides can treat scabies, while washing and drying clothes at hot temperatures can eradicate infestations in clothing and bedding.
Crusted (or Norwegian) scabies is a more serious and extremely infectious form of the disease. Crusted scabies affects large areas of the body, such as the hands and feet, causing scaly and crusted skin. Thousands of mites infest areas of skin under the crusts, which makes it difficult to kill the live mites and their eggs. Crusted scabies is mostly found among older people or people who are immunocompromised, such as organ transplant recipients and HIV/AIDS patients.
In some cases, scabies and crusted scabies can lead to serious complications, such as secondary infections and poststreptococcal glomerulonephritis, which is inflammation of the kidneys. Seek prompt medical care if you have symptoms of scabies, such as intense itching and a skin rash. Early diagnosis and treatment can minimize the spread of the disease and reduce the risk of complications.
What are the symptoms of scabies?
If a person has never had scabies, symptoms may not appear until four to six weeks after exposure to the mites that cause scabies. However, a person who has had scabies in the past may develop symptoms one to four days after exposure. An infected person can spread scabies even if symptoms have not yet appeared.
The main symptom of scabies is intense itching and scratching. Other symptoms include:
Irritations and sores due to intense scratching
Pimple-like, itchy rashes, which may include scales and blisters
Thin, irregular burrow tracks comprised of tiny blisters or bumps in skin folds
Where do symptoms appear?
Both children and adults can be affected by scabies anywhere on the body. However, the scabies mites tend to gather and burrow in warmer skin regions, such as areas under tight clothing, bracelets, watchbands and rings. They also burrow between the fingers and toes and in the skin folds of the elbow, knee, breast and genitals.
Common areas affected by itching and rash include:
Around the nipples
Between the fingers and toes
- Eyelid margin
Skin folds of the knees and elbows
Soles of the feet
Under the nails
Serious symptoms that might indicate a life-threatening condition
In some cases, scabies can lead to serious complications from secondary bacterial infections and poststreptococcal glomerulonephritis, which is inflammation of the kidneys. Seek immediate medical care (call 911) if you, or someone you are with, have any of these symptoms:
What causes scabies?
Scabies is an itchy skin condition caused by the bite of female mites known as “human itch mites,” or Sarcoptes scabiei. These eight-legged mites are attracted to warmth and odor and survive by burrowing into the upper layers of human skin, where they lay their eggs. After a few weeks, these bites result in an allergic reaction causing intense itching and scratching, especially at night.
Scabies is typically spread through prolonged, direct skin-to-skin contact, and it can pass easily between family members and sexual partners. Scabies represents a serious concern in crowded areas, such as hospitals, child care centers, prisons, and nursing homes.
Sarcoptes scabiei mites can also live in linens or clothing for 24 hours or more and can be spread by sharing infested clothes, towels or bedding in some cases. A rare but serious and infectious form of scabies called crusted, or Norwegian, scabies is easily spread through linens and clothing. Pets do not carry or spread human scabies.
What are the risk factors for scabies?
A number of factors may increase your chances of developing scabies. You can lower your risk of contracting scabies by avoiding common risk factors including:
- Crowded areas or unsanitary conditions, such as big cities, hospitals, child care centers, prisons, and nursing homes
- Direct, prolonged skin-to-skin contact with infected individuals, such as children, mothers of young children, and older people in nursing homes. Crusted (Norwegian) scabies may be spread by more casual contact.
- Immunocompromised health
- Poor personal hygiene
- Poor nutritional status
- Sharing unwashed clothes, towels and bedding
- Skin-to-skin contact through sexual activity, especially among young adults
How is scabies treated?
Scabies can be treated with prescription creams and lotions, known as scabicides, which kill the mites. Some medications also kill the eggs. Residual itching and inflammation after treatment with scabicides can be treated with antihistamines and corticosteroid creams. Complete treatment of the infestation also requires a comprehensive process to eradicate infestations in linens and clothing.
Applying scabies medications
To completely cure scabies, you must take the fully prescribed course of scabicide medications exactly as directed by your health care provider. Different types of scabicide medications are generally prescribed for different people and age groups. It is very important not to share your medication prescription with other people. Do not use insecticides intended for use on animals infected with different types of mites.
In general, the scabicide cream or lotion is applied from the neck down to the feet and toes for adults and older children. For infants and young children, it may be recommended that the medication be applied to the head and neck as well. Scabicides should be left on the body for the recommended time before being washed off. Clean clothes should be worn after each application.
Anyone with whom an infected person has had prolonged skin-to-skin contact, such as household members and sexual partners, should also be treated with a specific scabicide that is prescribed for that person. All potentially affected persons should be treated at the same time, even if they have no symptoms. This prevents spreading the infestation from an untreated person back to a person who has already been treated.
Medications may need to be reapplied if itching continues more than two to four weeks after treatment, or if new burrows or rashes appear. Your doctor or health care provider will advise you about the need for reapplication.
There is also an oral medication that may be prescribed in some cases. In the event that skin sores become infected with bacteria, your health care provider will prescribe antibiotics.
Eradication of scabies infestations in linen and clothing
It can be a challenge to get rid of a scabies infestation in the home, because scabies mites can survive in linen, carpeting, upholstery and clothing for up to two to three days. They can spread when household members or sexual partners have close skin contact with any of these items.
Decontamination methods for linens, clothing and rugs include:
Sealing in a plastic bag for at least 72 hours
Vacuuming all carpeting and upholstered furniture
Washing in hot water and drying in a hot dryer
What are the potential complications of scabies?
If scabies bites are scratched excessively, the skin can break down, leading to sores and secondary bacterial infections. In some cases, a bacterial infection can lead to additional serious complications, such as poststreptococcal glomerulonephritis. You can best treat scabies and lower your risk of these and other complications by following the treatment plan that you and your health care professional design specifically for you.
Complications of scabies can include:
Bacterial skin infections due to secondary infection with Staphylococcus aureus (staph) or streptococcal bacteria (strep)
Impetigo (bacterial infection of the skin)
Poststreptococcal glomerulonephritis (inflammation of the kidneys)
Recurrences of scabies infestation
- Skin sores and lesions due to heavy scratching of scabies