Overview
Scabies is a skin infestation caused by the human itch mite, Sarcoptes scabiei, which burrows into the top layer of skin, causing intense itching and a pimple-like rash.
Disease Summary
- Category
- Infectious Disease
- Cause
- Infestation of the skin by the human itch mite (Sarcoptes scabiei)
- Transmission
- Spreads through prolonged, direct skin-to-skin contact with an infested person; can also spread, less commonly, through shared bedding or clothing
- Body System
- Skin
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Symptoms can take four to eight weeks to appear after a first infestation, though reinfestation can cause symptoms within a few days.
Intense Itching
Often worse at night, itching is the most common and noticeable symptom.
Pimple-like Rash
A raised, bumpy rash typically appears in areas of mite activity.
Burrow Tracks
Thin, greyish-white lines on the skin surface where female mites have burrowed.
Rash in Common Areas
Often appears between the fingers, on the wrists, and around the waist, though it can differ in infants and young children.
Danger Signs
Seek prompt medical attention if any of the following develop.
Widespread Thick, Crusted Skin
May indicate crusted scabies, a severe form that requires urgent, aggressive treatment.
Signs of Skin Infection
Redness, warmth, or pus from scratched areas can indicate a bacterial skin infection.
Fever with Widespread Rash
May indicate a secondary infection and needs medical evaluation.
Dark or Foamy Urine
Can rarely occur if a bacterial skin infection leads to a related kidney complication.
Diagnosis
Clinical Assessment
Diagnosis is often based on the pattern of itching, rash location, and visible burrows.
Skin Scraping
A sample from a burrow can be examined under a microscope to look for mites, eggs, or fecal matter.
Dermoscopy
A handheld magnifying tool can help visualize mites or burrows directly on the skin.
Laboratory Tests
Skin Scraping Microscopy
Confirms the diagnosis by identifying mites, eggs, or fecal matter under a microscope.
Dermoscopy
A non-invasive way to visualize burrows and sometimes the mite itself.
Skin Biopsy (in select cases)
Occasionally used when the diagnosis remains unclear after other methods.
Treatment
Topical Scabicide
Prescription creams, such as permethrin, applied from the neck down are the standard treatment and kill the mites.
Oral Medication
Oral ivermectin is an alternative treatment option, taken in two doses about one to two weeks apart.
Prevention
Avoid direct skin-to-skin contact with an infested person
Scabies spreads through prolonged, direct contact, so avoiding this reduces the risk of infestation.
Avoid sharing clothing, towels, or bedding
These items can occasionally spread mites, particularly from someone with crusted scabies.
Wash items in hot water
Washing clothing, towels, and bedding in hot water and drying on high heat kills mites and eggs.
Treat close contacts simultaneously
Treating household members and close contacts at the same time helps prevent reinfestation.
Risk Factors
High Risk
These factors substantially increase the likelihood of scabies infestation.
- Close, prolonged skin-to-skin contact with an infested person
- Living in crowded settings, such as nursing homes or shelters
- Sharing a bed with someone who has scabies
Increased Risk
These factors are associated with a moderately higher risk of severe or crusted scabies.
- Weakened immune system
- Conditions that limit the ability to itch or scratch, such as paralysis
- Living or working in long-term care facilities
Additional Contributing Factors
Other factors linked with an increased likelihood of infestation or spread.
- Limited access to healthcare or delayed treatment
- Sexual contact with an infested person
- Close contact in childcare or school settings
Complications
Bacterial Skin Infection
Scratching can introduce bacteria, leading to skin infections that may need antibiotics.
Crusted Scabies
A severe, highly contagious form that occurs mainly in people with weakened immune systems.
Post-streptococcal Complications
Rarely, a bacterial skin infection from scabies can lead to kidney inflammation.
When to Seek Medical Care
Widespread or Crusted Rash
May indicate crusted scabies, which needs urgent, aggressive treatment.
Signs of Skin Infection
Redness, warmth, or pus from scratched areas needs medical assessment.
Fever
Fever alongside a widespread rash may indicate a secondary infection.
Symptoms Not Improving After Treatment
Itching or new burrows appearing one to two weeks after treatment may mean retreatment is needed.
Prognosis
Good with Appropriate Treatment
Prescription treatment is highly effective at killing the mites causing infestation.
Itching May Continue After Treatment
Itching can persist for several weeks after treatment due to an ongoing allergic reaction, even once the mites are gone.
Excellent Long-term Outlook
With appropriate treatment, scabies fully resolves without lasting effects for most people.
Differential Diagnosis
Eczema
Can cause itching and rash but typically lacks the characteristic burrows seen in scabies.
Contact Dermatitis
An allergic or irritant skin reaction that can resemble scabies but is linked to a specific exposure.
Insect Bites
Can cause itchy bumps similar to scabies but usually appear in exposed areas rather than the characteristic scabies distribution.
Impetigo
A bacterial skin infection that can develop as a complication of scabies or occur independently.
References
Centers for Disease Control and Prevention (CDC)
CDC guidance on the causes, spread, and prevention of scabies.
Centers for Disease Control and Prevention (CDC), Symptoms
CDC guidance on recognizing scabies symptoms and complications.
World Health Organization (WHO)
WHO fact sheet on scabies symptoms, transmission, and treatment.
Frequently Asked Questions
Is scabies contagious?
Yes. Scabies spreads through prolonged, direct skin-to-skin contact, and a person can spread it even before symptoms appear.
Can scabies go away on its own?
No. Scabies requires prescription treatment to kill the mites; it will not resolve without treatment.
Why does itching continue after treatment?
Itching is caused by an allergic reaction to the mites and their waste, so it can persist for several weeks even after the mites are killed.
Do I need to treat my whole household?
Yes. All household members and close contacts should be treated at the same time, even without symptoms, to prevent reinfestation.