Scabies Causes, Symptoms, and Treatment
Table of Contents
- Written by Dr. Patricia Shelton on March 18, 2022
Scabies is a skin infection that’s caused by a parasite called Sarcoptes scabiei. This is a small arthropod (a bug similar to a tick or spider) that burrows into the top layer of the skin, where it lives and lays its eggs. It causes a bumpy rash that is intensely itchy.
Many people have questions about this disease. In what ways are scabies contagious? Is scabies a sexually transmitted disease? How can scabies be treated? Here are answers to some of the most common questions about scabies.
How can scabies be transmitted?
Scabies is transmitted through any type of prolonged skin-to-skin contact. This includes sexual contact, which almost always lasts long enough for the mites to spread. Scabies can also be transmitted through sharing items like clothing, towels, and blankets, if these are not washed in between the different people using them.
Scabies tends to spread rapidly under conditions where people are crowded together, such as in nursing homes and prisons. However, it can affect people of any social class, and can spread easily between people who are living together. It also tends to spread easily in schools.
Scabies can infect the skin of any part of the body. However, the mites prefer to burrow in places that are usually covered by clothing, including the buttocks, groins, genitals, and around the nipples. This is part of why scabies can easily be transmitted through sexual contact. The mites also prefer the areas between the fingers, and the inside of the elbows and wrists.
Although there are also other diseases that can cause bumps on and around the genitals (including herpes and molluscum contagiosum), the bumps of scabies are different. They’re pink bumps that cause intense itching, and you may also be able to see wavy lines on your skin, which are caused by the mites burrowing just under the surface of your skin.
Are there different types of scabies?
Scabies is always caused by the same species of mite. Although it can spread in different ways (through sexual contact, other skin-to-skin contact, or on surfaces), it’s ultimately the same infection. No matter how you got scabies, it’s the same disease, and the treatment will be the same.
People who are immunocompromised (such as the elderly and people with chronic diseases) may develop a form of scabies known as crusted scabies, also known as Norwegian scabies. Instead of itchy red bumps, the skin forms a crust, which contains a very large number of scabies mites and eggs. Although the disease looks somewhat different, it’s actually the same disease, only in a more severe form. People with crusted scabies can spread the disease very easily because of the large numbers of the mites that they’re carrying, and should be urgently treated so that they don’t cause an outbreak.
There are other species of mites that can affect animals. However, the mite that causes scabies only infects humans. You cannot get scabies from your pet, or give scabies to your pet.
How fast can scabies spread?
It takes about ten minutes of skin-to-skin contact for scabies to spread. Although spread won’t occur through casual contact, a sexual encounter will almost certainly be long enough to lead to catching scabies.
Even a person who’s asymptomatic can still spread scabies. They may have just a few mites in their skin, but if some of those are transferred to someone else, then they can cause a scabies infection. It can take 4-8 weeks for someone to develop symptoms after getting scabies, but they can still transmit the infection before they show symptoms.
How long to cure scabies?
Scabies is generally treated with a prescription cream or lotion containing a medication called permethrin. This is an insecticide that kills the mites. Usually, it’s recommended that everyone in the house be treated, even if they don’t have symptoms. This helps to prevent family members from passing the infection back and forth to each other. Anyone that you’ve recently had sexual contact with should also be treated. It’s also very important to wash all bedding, towels, and clothing in hot water, to ensure that the mites and their eggs are destroyed.
In many cases, the infection is treated after just one application of the prescription. It’s put on the body, left on for a fairly long period (about 8-24 hours, depending on the specific preparation), and then washed off. The treatment may be repeated after a week to ensure that all of the mites have been killed.
Although the treatment kills the mites, the rash and the itching may take a few weeks to heal. This happens because your skin is still reacting, even though the mites themselves are now gone. Your doctor can prescribe medication to help with itching, if it’s bothering you or preventing you from sleeping.
After scabies treatment are you still contagious?
After the first treatment, you’re no longer considered contagious. It’s safe for you to return to school, sports, or work.
How long do scabies last off of a human body?
After a scabies infection, it’s generally recommended that you wash all clothing, towels, and bedding items in hot water and then dry them on the hot setting in the dryer, in order to ensure that you’ve destroyed all the mites and their eggs. However, there may be some items that can’t withstand this treatment. In this case, you can put the items into a plastic bag and seal it for at least 72 hours. The mites can’t live for longer than 2-3 days off of human skin, so this will ensure that they all die and the item is safe to use again.
What happens if scabies is left untreated?
If scabies is left untreated, then the life cycle of the mites can continue indefinitely. They will continue to lay eggs, which will mature into adult mites, breed, and lay new eggs. There’s no way to wash them off. Without treatment, you could have scabies for a long time.
Is scabies included in an STD test?
Scabies is not always included in a standard STD test (whether a clinic or a home STD test). However, the test can rule out other possible causes of a genital rash, such as herpes. If you suspect that you have scabies, then you should get a specific test for scabies. A doctor can usually diagnose it by taking a scraping of the rash and looking for the mites under a microscope. If someone that you’ve had sexual contact with in the past month is diagnosed with scabies, then you should also be treated, as it’s likely that you have it too and just haven’t developed symptoms yet.
Leung AKC, Lann JM, et al. Scabies: A Neglected Global Disease. Curr Pediatr Rev 2020;16(1):33-42. doi: 10.2174/1573396315666190717114131.
Orrico JA, Krause-Parello CA. Facts, fiction, and figures of the Sarcoptes scabiei infection. J Sch Nurs 2010 Aug;26(4):260-6. doi: 10.1177/1059840510375413.
Parasites - Scabies. Centers for Disease Control and Prevention (2010). https://www.cdc.gov/parasites/scabies/index.html. Accessed 17 March 2022.
Scabies. Cedars Sinai Medical Center (2021). https://www.cedars-sinai.org/health-library/diseases-and-conditions/s/scabies.html. Accessed 17 March 2022.
Scabies. Mayo Clinic (2020). https://www.mayoclinic.org/diseases-conditions/scabies/symptoms-causes/syc-20377378. Accessed 17 March 2022.
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