What Is Scabies? Rash, Treatment, Symptoms, Pictures
What Is Scabies?
Scabies is a skin condition caused by an infestation of the human itch mite called Sarcoptes scabiei. These microscopic mites burrow into the skin and cause symptoms of itching and rash.
How Do You Get Scabies?
Anyone can get scabies. It is found all over the world and the mite is
transmitted by direct and prolonged skin-to-skin contact with a person
who has scabies. Sexual contact is the most common way scabies is
transmitted. Transmission can also happen from parents to children,
particularly mother-to-infant. The mite can only survive about 48 to 72
hours without human contact, so it is uncommon, though possible, for
scabies to spread through infested bedding or furniture.
How Long Does Scabies Last?
Scabies mites can only live about 72 hours without human contact, but
once on a person, the mites can live up to two months. Mites survive
longer in colder conditions with higher humidity. Once on a person,
mites can burrow into the skin, and symptoms usually begin three to six
weeks after infestation.
Can You Catch Scabies from a Dog or Cat?
Animals do not spread the same types of mites that cause human scabies,
so it is not possible to catch scabies from a dog or cat. The type of
scabies that can infest pets is called "mange." Mange mites can spread
to humans and cause minor itching and redness, but those mites cannot
survive or reproduce on human skin and will die out on their own,
limiting symptoms in humans. People do not need to be treated if they
come into contact with mange, but dogs and cats must be treated because
mange can spread and cause fur loss, and scaly and itchy skin in pets.
What Are the Signs and Symptoms of Scabies?
Symptoms of scabies are usually itching
(which tends to be more intense at night), and a pimple-like rash.
Scabies rash can appear on any part of the body, but the most common
sites are wrists, elbows, armpits, the skin between the fingers and toes
and around the nails, and skin usually covered by clothing such as the
buttocks, belt line, nipples, and penis. Infants and young children may
have scabies rash on their head, face, neck, palms, and soles.
In some patients with weakened immune systems, scabies rash may become crusted.
In some patients with weakened immune systems, scabies rash may become crusted.
What Does a Scabies Infection Feel Like?
Scabies causes
intense itching, often worst at night. The itching starts as a minor
nuisance and progresses to a point where the infested person cannot
sleep.
How Is Scabies Tested and Diagnosed?
Scabies is
usually diagnosed by the patient's history and a physical examination of
the lesions (bumps). Other tests that may be done include:
- Skin scraping to identify the mites or eggs
- Dermoscopy, which uses a handheld dermoscope to allow closer visual examination of the skin to look for mites
- Adhesive tape test in which a doctor uses strong adhesive tape applied to the skin lesions and then pulled off and viewed under a microscope to check for mites
Scabies Treatment: Cream Applications
There are no
over-the-counter approved treatments for scabies. A doctor must
prescribe treatment. A first-line treatment for scabies may involve a
topical cream, such as permethrin (Elimite), which is applied directly
to the skin, from the neck to the soles of the feet. It should be left
on overnight and then washed off 8 to 14 hours later. Usually a second
application after 1 to 2 weeks is recommended.
Other topical scabies treatments include crotamiton (Crotan, Eurax) cream or lotion, lindane (not usually used as a first-line treatment due to risk of seizures), sulfur ointment, and benzyl benzoate (not available in the United States).
Other topical scabies treatments include crotamiton (Crotan, Eurax) cream or lotion, lindane (not usually used as a first-line treatment due to risk of seizures), sulfur ointment, and benzyl benzoate (not available in the United States).
Scabies Treatment: Oral Medication
In some cases,
oral ivermectin may be used, particularly in cases where scabies covers a
large part of the body and is crusted. It is also often used in
settings such as nursing homes where there may be widespread outbreaks.
The Centers for Disease Control (CDC) recommends a dose of 200 mcg/kg as
a single dose, repeated in two weeks. The advantages of oral ivermectin
are that it is easy to use and it does not cause related skin problems.
However, oral ivermectin can cause unwanted side effects so it is not
always the first choice treatment.
Scabies Treatment: Antihistamines
To get relief
from the symptom of itching, some over-the-counter antihistamines such
as diphenhydramine (Benadryl) may help control the itch and allow sleep.
Scabies Treatment: Wash Linens and Bedclothes
Scabies mites do
not survive more than 72 hours without human contact. It is usually
sufficient to machine wash bed linens and clothing in hot water and dry
on high heat, or have the items dry-cleaned. It is not necessary to have
furniture or carpets cleaned as the mites will die off on their own in a
few days without human contact.
Scabies Treatment: Additional Tips
Some additional ways you can treat scabies mites or prevent them from spreading include:
- Make sure everyone who is in contact with the infested person is treated, particularly those who come in frequent, close contact with that person (i.e., sexual partners, people who live with the infested person, small children and infants cared for by an infested parent).
- Keep fingernails and toenails well trimmed and clean of any mites or eggs.
- Thoroughly vacuum carpets, furniture, and car interiors. Use extra caution vacuuming after someone who has crusted mites, as these are more contagious. Discard the vacuum cleaner bags or clear out the dirt receptacle when done.
- Avoid scratching bumps or lesions.
- Keep open sores clean.
- Remember that once treatment starts it may still take a few days for itching and other symptoms to subside. If it does not go away, see a doctor.
Are Cases of Scabies Often Misdiagnosed?
In What Special Situations Can Scabies Be More Easily Spread?
Scabies may
spread more easily in nursing homes and other extended-care facilities
because of the close contact of residents and staff. Scabies mites can
also more easily spread among people with compromised immune systems,
such as people with HIV/AIDS, or cancer.
What Is “Norwegian Scabies”?
"Norwegian scabies" is another name for crusted scabies, which tends to
occur more often in patients with compromised immune systems due to
conditions such as HIV/AIDS or cancer, or in the elderly, and in
patients with Down syndrome. Patients with crusted scabies have large
numbers of scabies mites and are very contagious. It can affect any area
of the body but the scalp, hands, and feet are most commonly affected.
The scales become warty, with crusts and fissures. Lesions may have an
unpleasant odor. Nails may be thick and discolored, and patients may or
may not have symptoms of itching.
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