How Do You Catch Scabies?

Scabies is an itchy skin condition caused by a mite infestation, usually contracted through skin-to-skin contact. Pictured is a colorized microscopic view of the scabies mite, which is a fraction of a millimetre in size.

Scabies is an infestation by a mite called Sarcoptes scabiei. These mites are just 1/3-millimeter-long, are eight-legged parasites (in contrast to insects, which have six legs), and burrow into the skin which creates intense itching that is worse at night.

Symptoms of scabies include:

• Itching, which is usually more intense at night
• Pimple-like rash
• Small red bumps
• Blisters
• Scales
• Infected sores if the rash is scratched

Itching and rash may be anywhere on the body, but common sites include:

• Webbing between the fingers and toes
• Area around the nails
• Wrists
• Elbows
• Armpits
• Knees
• Waist and belt-line
• Nipples
• Buttocks
• Genitals
• The sides and backs of the feet
• Head, face, neck, palms, and soles (in infants and young children)

Scabies is contagious and is caused by direct and prolonged skin-to-skin contact with a person who has scabies. The most common way scabies is transmitted is via sexual contact, but the mite can also be transmitted from parents hugging children, particularly mother-to-infant.

The diagnosis of scabies is typically made with a physical examination of the scabies lesions and the patient’s history. 

Other tests that may be used to diagnose scabies include:

• Skin scraping to look for the mites or eggs
• Dermoscopy, which uses a handheld device with a light source and magnifier to allow closer visual examination of the skin to inspect for mites
• Adhesive tape test, in which a strong adhesive tape is applied to the skin lesions, pulled off and viewed under a microscope to check for mites
• A felt-tip-marker test, whereby a doctor draws on the rash with a washable felt-tip marker and then wipes it off with alcohol to help to identify a burrow 

Medications for scabies include:

• Permethrin (Elimite), a mite-killer
• Crotamiton (Eurax) cream or lotion, a mite-killer that also helps with itching
• Lindane (not a first-line treatment due to a risk of seizures), a mite-killer
• Sulfur ointment
• Oral ivermectin (Stromectol), an antiparasitic
• Diphenhydramine (Benadryl) for itching

Avoid scratching the bumps and keep any open sores clean to avoid secondary infection. If infection occurs, antibiotics may be needed. 

In some cases, mites may be difficult to find and even if tests are negative treatment may still be recommended if the doctor suspects scabies is present. 

Mites don't live more than 72 hours away from the body, so washing bedding and towels in hot water and drying on high heat is enough to kill mites. If items cannot be washed, dry cleaning is recommended. Items can also be sealed in a plastic bag for at least one week, which is sufficient time for all mites to die off. 

Mites will die off on their own in a few days if there is no contact with humans. It is usually not necessary to deep clean furniture and carpets. However, crusted scabies is considered very infectious, so careful vacuuming of furniture and carpets in rooms used by infested persons is recommended.

To prevent scabies mites from spreading: 

• Everyone who is in contact with an infested person should be treated, especially those who come into frequent, close contact with that person (i.e., sexual partners, household members, small children and infants of an infested parent)
• Keep fingernails and toenails well-trimmed and clean of any mites or eggs
• Do not scratch bumps or lesions