Scabies Symptoms, Causes & Treatment Options

Scabies is a very itchy rash caused by mites living in and on the skin. It is curable via topical or oral medications, and most infestations will also require cleaning of clothing and furniture.

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Contents

  1. Overview
  2. Symptoms
  3. Potential Causes
  4. Treatment, Prevention and Relief
  5. When to Seek Further Consultation
  6. References

What Is Scabies?

Summary

Scabies is an itchy rash that occurs when the Sarcoptes scabiei mite infests the skin, burrowing and laying eggs there. Scabies will be very itchy and will look like red bumps, linear burrows, pustules, scaling, and may even have excoriations around it from itching. Scabies most often affects the areas between fingers and toes, the genitals, ankles, wrists, and armpits. It is spread from direct skin-to-skin contact, including sexual contact, or through shared clothing or furniture. Scabies is usually treated with topical creams to kill the mites. Oral medications are also available, and additional medications may be necessary to reduce itch during treatment. Complete treatment of a scabies outbreak will require treatment of family members and close contacts (even those without symptoms) as well as thorough washing of clothing, furniture, and housing.

Recommended care

Scabies Symptoms

Main symptoms

Scabies infestation will generally present with the following symptoms:

  • Itching: Scabies infestation is known to be one of the very itchiest conditions possible. Itching may be especially bad after hot showers or at night. Itching can sometimes persist for several weeks even after proper treatment [1].
  • Burrows: Burrows are a unique feature of scabies infestation though they are not always present. They look like small linear red or gray tracks in the skin.
  • Papules: Papules are red or pink bumps that may occur alone or in groups or clumps as a part of a scabies infestation.
  • Scale and crust: The skin overlying papules and burrows may peel and flake.
  • Excoriations: Scabies infestation is so itchy that the scratching itself may cause wounds in the skin, named excoriations.
  • Vesicles: In infants and small children, scabies may present as vesicles (fluid-filled bumps resembling small blisters) or pustules (pus-filled bumps resembling acne) [2].
  • Distribution: The itching and the skin markings described above tend to appear in the following locations, which scabies mites prefer: the spaced between the fingers and toes, the insides of the wrists, the ankles, the genitals, and the armpits. Scabies infestations also tend to spare the scalp [3].

Complications

In the following cases, scabies infestations may become more severe and require extra treatments:

  • Superinfection: The scabies rashes above may become infected with native skin bacteria, or infectious foreign bacteria, and can transform into a folliculitis, or cellulitis. Look for redness, swelling, pus, and hot, firm skin to indicate a superinfection.
  • Crusted scabies: Crusted scabies (or Norwegian scabies) occurs in severe scabies infestations, that are more likely to affect people with weakened immune systems. Crusted scabies will present as thick crusts of skin, often on the hands or feet that may not itch at all. Crusted scabies is especially infectious to others since the crusting, shedding skin can contain large numbers of scabies mites and eggs.

Asymptomatic infestation

It is also important to know that not all scabies infestations will have symptoms – it is possible for someone to carry and transmit scabies mites without having any symptoms at all!

Scabies Causes

Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which is a microscopic arthropod. The scabies mite has evolved specifically to live in the stratum corneum layer of human skin. Adult scabies mites live for about 10-20 days, burrowing into the skin to lay their eggs. Adult mites, eggs, larva, and scabies feces, called scybala can all be detected in scabies infestations.

A scabies infestation is usually spread from one person to another by the following routes:

  • Direct skin contact: This must occur over a somewhat longer period of time – a handshake is usually not dangerous.
  • Sexual contact
  • Fomites: This means spreading mites through clothing, furniture, and other objects. Mites can only live an average of 3 days without a host, though some sources claim that mites can live on a fomite for up to 6 weeks [1].
  • Asymptomatic individuals: Remember that someone can carry and spread scabies without showing any symptoms!

Certain types of people may be at a greater risk of acquiring a scabies infestation. Some of these categories are listed below:

  • Immunocompromised: People with compromised immune systems are more likely to have cases of scabies that are severe (crusted) or complicated by infection.
  • Communal living: People in crowded conditions or those residing in group homes, like residents of nursing homes or hospitals, are more likely to acquire scabies [4].
  • Small children: Small children are likely to acquire scabies because of skin contact, residing in groups, and less developed hygiene. Parents of small children are also at increased risk.
  • Sexually active individuals

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Treatment Options, Relief, and Prevention for Scabies

Treatment

A dermatologist will usually be able to diagnose and treat scabies within about a week. The doctor may diagnose scabies in several ways: One way is from clinical appearance alone. The doctor may also diagnose by examining skin with a special magnifying glass called a dermatoscope to see mites or eggs directly. The most specific way of diagnosing scabies is using a blade to gently scrape at a scabies burrow (this should not be painful) and examining recovered mites, eggs, or scybala under a microscope. After definitive diagnosis, scabies can be treated as follows:

  • Topical medications: Most cases will respond to two overnight applications of permethrin 5% cream over the entire body from the neck to the toes, 1 week apart.
  • Special cases: In cases where the infection occurs in someone who is immunocompromised, infants, or the elderly, you may need to apply the permethrin cream to the face and scalp as well.
  • Symptom relief: Since itch may persist even after effective treatment, topical steroids (like hydrocortisone or triamcinolone) or antihistamines like diphenhydramine (Benadryl) or cetirizine (Zyrtec) may provide symptomatic relief from itch [2].
  • Oral medications: Oral ivermectin (200mcg/kg) is another treatment option that may be selected instead of, or in addition to topical creams. This may be more convenient for some, or more effective.
  • Crusted scabies: Crusted scabies may require a longer and more intensive course of treatment that should be guided by your dermatologist [1].
  • Rooms should be cleaned thoroughly with normal household products and carpets should be vacuumed, but fumigation is not required [1].

Prevention

In addition to treating the initial scabies infection, additional efforts must be made to prevent the spread of the infestation, or a re-infestation after treatment. Key actions to prevent spread and re-infestation include:

  • Treat ALL contacts: In a confirmed case of scabies, all family members living with the affected individual should receive full scabies treatment, regardless of whether they are showing symptoms of scabies. Close personal contacts and sexual partners should be included in this group as well.
  • Wash clothing and bedding: All clothing and bedding of the affected individual, as well as close contacts, should be washed in hot water and dried on high heat to kill any remaining mites, which can otherwise survive for up to 6 weeks.
  • Seal non-washable items in plastic: Non-washable items should be sealed in air-tight plastic bags for at least 10 straight days to kill mites. This includes furniture.
  • Clean and vacuum inhabited rooms: It is good practice to thoroughly clean any rooms involved in a scabies infestation with normal household products. Any carpeted rooms should be vacuumed well. It is NOT necessary to fumigate or use special cleaning products.

When to Seek Further Consultation for Scabies

If you suspect that you have scabies, you should see a dermatologist or primary care doctor immediately to receive a diagnosis and prompt treatment. Any delay in treatment could mean spreading the infestation to family and close contacts.

It is especially important to seek further consultation if your scabies has failed to respond to normal treatment – this may mean that the diagnosis is incorrect or that a stronger treatment is required.

You should also seek consultation immediately if you suspect a superinfection of scabies, as this can progress from discomfort to a life-threatening infection.

Finally, if you are immunocompromised or suspect crusted scabies, seek consultation immediately.