What is scabies?
Scabies is a contagious, itchy skin disease from an infestation of Sarcoptes scabiei. This microscopic mite burrows under the skin, causing a scabies rash and intense itching. Itching most often occurs at night and may be accompanied by burrows, pimple-like irritations or rashes, and sores from 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.
Scabies spreads through direct 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 spreads by sharing unwashed clothes, towels and bedding. Your pets are not able to spread human scabies, but they can get a different mite infection called mange.
It is important to know that even people with good personal hygiene can catch scabies. Fortunately, effective medications called scabicides can treat scabies. Washing and drying clothes at hot temperatures can eradicate infestations in clothing and bedding.
In some cases, 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 different types of scabies?
There is only one type of mite that causes scabies in humans. However, there can be subtypes in how the infestation presents clinically. Other than the traditional symptoms and presentation, rare subtypes of scabies include:
Bullous scabies forms large, fluid-filled blisters that can measure nearly 0.5 inches. The blisters can appear anywhere on the body, but commonly develop on the trunk and extremities. This subtype tends to affect older males most often.
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 mostly affects older people or people who are immunocompromised, such as organ transplant recipients and HIV/AIDS patients.
- Nodular scabies occurs when itchy nodules—or lumps—develop and persist for months after a scabies infection. This is likely due to an allergic reaction to leftover parts of the mite. It most often affects the genitals.
What are the symptoms of scabies?
If a person has never had scabies, symptoms may not appear until 4 to 6 weeks after exposure to the mites that cause scabies. However, a person who has had scabies in the past may develop symptoms 1 to 4 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 scabies symptoms include:
Irritations and sores due to intense scratching
Pimple-like, itchy rashes, which may include scales and blisters
- Thin, irregular burrow tracks composed of tiny blisters or bumps in skin folds
It is also possible to develop nodules.
Where do symptoms appear?
Both children and adults can get 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, watch bands, 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
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) for any of these symptoms:
What causes scabies?
Sarcoptes scabiei mites can also live in linens or clothing for 24 hours or more and can spread by sharing infested clothes, towels or bedding in some cases. Pets do not carry or spread human scabies.
Scabies is an itchy skin condition from 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 typically spreads 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.
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, and nursing homes
Direct, prolonged skin-to-skin contact with infected individuals, such as children, mothers of young children, and older people living in nursing homes. Crusted (Norwegian) scabies may be spread by more casual contact.
Poor personal hygiene
Poor nutritional status
Sharing unwashed clothes, towels and bedding
- Skin-to-skin contact through sexual activity, especially among young adults
How do you prevent scabies?
You may be able to prevent spreading scabies and re-infestation of scabies by:
Avoiding skin-to-skin contact with an infected person and contact with clothes, bedding, towels, and other items an infected person has used
Cleaning all clothes, linens, bedsheets and towels that an infected person used within three days of starting treatment. Use the hottest water safe for the items and dry on high heat. Dry clean items you cannot wash.
Placing items you cannot wash or dry clean in a plastic garbage bag and sealing it. Keep the sealed bag in a garage or other space for up to two weeks to kill the mites.
Staying home until the day after treatment begins
Treating family members and close contacts at the same time as the infected person
- Vacuuming and cleaning rooms an infected person has used
How do doctors diagnose scabies?
To diagnose scabies, your doctor will take a medical history and perform a physical exam. Sometimes, testing may be necessary. Questions your doctor may ask include:
What symptoms are you experiencing?
When did your symptoms start?
What parts of the body are your symptoms affecting?
Are your symptoms worsening or staying the same?
Does anyone else in the household or other close contact have similar symptoms?
For children, is your child in a child care program?
What medical conditions do you have?
- What medications do you take?
In most cases, the physical exam alone can diagnose scabies. Your doctor can usually make the diagnosis by observing the rash and characteristic burrows. Doctors may take a skin scraping from a burrow or attempt to remove the mite with a needle tip. They may also use a dermatoscope to magnify the burrow and find the mite. This method can assist with finding mites in dark or hairy skin. In some cases, it may be necessary to take a skin biopsy to confirm the presence of mites.
How do you treat scabies?
Scabies treatment involves prescription creams and lotions, known as scabicides, which kill the mites. Some medications also kill the eggs. Doctors treat itching and inflammation with antihistamines and corticosteroid creams. Complete scabies treatment also requires a thorough process to wipe out infestations in linens and clothing.
Applying scabies medications
To completely cure scabies, you must complete the course of scabicide medications exactly as your doctor prescribes. Doctors may use different types of scabicide medications for different people and age groups. It is very important not to share your prescription medication with other people. Do not treat human infections with insecticides intended for use on animals infected with different types of mites.
In general, you apply the scabicide cream or lotion from the neck down to the feet and toes for adults and older children. For infants and young children, doctors may recommend applying the medication to the head and neck as well. Leave the scabicide on the body for the recommended time before washing it off. Wear clean clothes after each application.
People who have prolonged skin-to-skin contact with an infected person should also receive treatment. This includes household members and sexual partners. Doctors will prescribe a specific scabicide 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 completed treatment.
Medications may need reapplication if itching continues for more than 2 to 4 weeks after treatment, or if new burrows or rashes appear. Your doctor or healthcare provider will advise you about the need for reapplication.
There is also an oral medication that doctors may prescribe in some cases. In the event that skin sores become infected with bacteria, your doctor will prescribe antibiotics.
Eradication of scabies infestations in linen and clothing
Scabies mites can survive in linen, carpeting, upholstery and clothing for up to 2 to 3 days. This can make it a challenge to get rid of a scabies infestation in the home. Mites can spread when household members or sexual partners have close skin contact with any of these infected 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 clothes or linens in hot water and drying in a hot dryer
What are the potential complications of scabies?
Scratching scabies bites excessively can break down the skin. This can lead 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 doctor 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