What is
scabies?
Scabies is an infestation of
the skin by the human itch mite (Sarcoptes scabiei var. hominis).
The microscopic scabies mite burrows into the upper layer of the skin where it
lives and lays its eggs. The most common symptoms of scabies are intense
itching and a pimple-like skin rash. The scabies mite usually is spread by
direct, prolonged, skin-to-skin contact with a person who has scabies.
Scabies is found worldwide and
affects people of all races and social classes. Scabies can spread rapidly
under crowded conditions where close body and skin contact is frequent.
Institutions such as nursing homes, extended-care facilities, and prisons are
often sites of scabies outbreaks. Child care facilities also are a common site
of scabies infestations.
What is crusted (Norwegian) scabies?
Crusted scabies is a severe
form of scabies that can occur in some persons who are immunocompromised (have
a weak immune system), elderly, disabled, or debilitated. It is also called
Norwegian scabies. Persons with crusted scabies have thick crusts of skin that
contain large numbers of scabies mites and eggs. Persons with crusted scabies
are very contagious to other persons and can spread the infestation easily both
by direct skin-to-skin contact and by contamination of items such as their
clothing, bedding, and furniture. Persons with crusted scabies may not show the
usually signs and symptoms of scabies such as the characteristic rash or
itching (pruritus). Persons with crusted scabies should receive quick and
aggressive medical treatment for their infestation to prevent outbreaks of
scabies.
How soon after infestation do symptoms of scabies begin?
If a person has never had
scabies before, symptoms may take as long as 4-6 weeks to begin. It is
important to remember that an infested person can spread scabies during this
time, even if he/she does not have symptoms yet.
In a person who has had
scabies before, symptoms usually appear much sooner (1-4 days) after exposure.
What are
the signs and symptoms of scabies infestation?
The most common signs and
symptoms of scabies are intense itching (pruritus), especially at night, and a
pimple-like (papular) itchy rash. The itching and rash each may affect much of
the body or be limited to common sites such as the wrist, elbow, armpit,
webbing between the fingers, nipple, penis, waist, belt-line, and buttocks. The
rash also can include tiny blisters (vesicles) and scales. Scratching the rash
can cause skin sores; sometimes these sores become infected by bacteria.
Tiny burrows sometimes are
seen on the skin; these are caused by the female scabies mite tunneling just
beneath the surface of the skin. These burrows appear as tiny raised and
crooked (serpiginous) grayish-white or skin-colored lines on the skin surface.
Because mites are often few in number (only 10-15 mites per person), these
burrows may be difficult to find. They are found most often in the webbing between
the fingers, in the skin folds on the wrist, elbow, or knee, and on the penis,
breast, or shoulder blades.
The head, face, neck, palms,
and soles often are involved in infants and very young children, but usually
not adults and older children.
Persons with crusted scabies
may not show the usual signs and symptoms of scabies such as the characteristic
rash or itching .
How did I get scabies?
Scabies usually is spread by
direct, prolonged, skin-to-skin contact with a person who has scabies. Contact
generally must be prolonged; a quick handshake or hug usually will not spread
scabies. Scabies is spread easily to sexual partners and household members.
Scabies in adults frequently is sexually acquired. Scabies sometimes is spread
indirectly by sharing articles such as clothing, towels, or bedding used by an
infested person; however, such indirect spread can occur much more easily when
the infested person has crusted scabies.
How is scabies infestation diagnosed
Diagnosis of a scabies
infestation usually is made based on the customary appearance and distribution
of the rash and the presence of burrows. Whenever possible, the diagnosis of
scabies should be confirmed by identifying the mite, mite eggs, or mite fecal
matter (scybala). This can be done by carefully removing a mite from the end of
its burrow using the tip of a needle or by obtaining skin scraping to examine
under a microscope for mites, eggs, or mite fecal matter. It is important to
remember that a person can still be infested even if mites, eggs, or fecal
matter cannot be found; typically fewer than 10-15 mites can be present on the
entire body of an infested person who is otherwise healthy. However, persons with
crusted scabies can be infested with thousands of mites and should be
considered highly contagious.
How long
can scabies mites live?
On a person, scabies mites can
live for as long as 1-2 months. Off a person, scabies mites usually do not
survive more than 48-72 hours. Scabies mites will die if exposed to a
temperature of 50°C (122°F) for 10 minutes.
Can
scabies be treated?
Yes. Products used to treat
scabies are called scabicides because they kill scabies mites; some also
kill eggs. Scabicides to treat human scabies are available only with a doctor’s
prescription; no "over-the-counter" (non-prescription) products have
been tested and approved for humans.
Always follow carefully the
instructions provided by the doctor and pharmacist, as well as those contained
in the box or printed on the label. When treating adults and older children,
scabicide cream or lotion is applied to all areas of the body from the neck
down to the feet and toes; when treating infants and young children, the cream
or lotion also is applied to the head and neck. The medication should be left
on the body for the recommended time before it is washed off. Clean clothes
should be worn after treatment.
In addition to the infested
person, treatment also is recommended for household members and sexual
contacts, particularly those who have had prolonged skin-to-skin contact with
the infested person. All persons should be treated at the same time in order to
prevent reinfestation. Retreatment may be necessary if itching continues more
than 2-4 weeks after treatment or if new burrows or rash continue to appear.
Never use a scabicide intended
for veterinary or agricultural use to treat humans!
Who
should be treated for scabies?
Anyone who is diagnosed with
scabies, as well as his or her sexual partners and other contacts who have had
prolonged skin-to-skin contact with the infested person, should be treated.
Treatment is recommended for members of the same household as the person with
scabies, particularly those persons who have had prolonged skin-to-skin contact
with the infested person. All persons should be treated at the same time to
prevent reinfestation.
Retreatment may be necessary
if itching continues more than 2-4 weeks after treatment or if new burrows or
rash continue to appear.
How soon after treatment will I feel better?
If itching continues more than
2-4 weeks after initial treatment or if new burrows or rash continue to appear
(if initial treatment includes more than one application or dose, then the 2-4
time period begins after the last application or dose), retreatment with
scabicide may be necessary; seek the advice of a physician.
Did I get
scabies from my pet?
No. Animals do not spread
human scabies. Pets can become infested with a different kind of scabies mite
that does not survive or reproduce on humans but causes "mange" in
animals. If an animal with "mange" has close contact with a person,
the animal mite can get under the person’s skin and cause temporary itching and
skin irritation. However, the animal mite cannot reproduce on a person and will
die on its own in a couple of days. Although the person does not need to be
treated, the animal should be treated because its mites can continue to burrow
into the person’s skin and cause symptoms until the animal has been treated
successfully.
Can
scabies be spread by swimming in a public pool?
Scabies is spread by prolonged
skin-to-skin contact with a person who has scabies. Scabies sometimes also can
be spread by contact with items such as clothing, bedding, or towels that have
been used by a person with scabies, but such spread is very uncommon unless the
infested person has crusted scabies.
Scabies is very unlikely to be
spread by water in a swimming pool. Except for a person with crusted scabies,
only about 10-15 scabies mites are present on an infested person; it is
extremely unlikely that any would emerge from under wet skin.
Although uncommon, scabies can
be spread by sharing a towel or item of clothing that has been used by a person
with scabies.
How can I
remove scabies mites from my house or carpet?
Scabies mites do not survive
more than 2-3 days away from human skin. Items such as bedding, clothing, and
towels used by a person with scabies can be decontaminated by machine-washing
in hot water and drying using the hot cycle or by dry-cleaning. Items that
cannot be washed or dry-cleaned can be decontaminated by removing from any body
contact for at least 72 hours.
Because persons with crusted
scabies are considered very infectious, careful vacuuming of furniture and
carpets in rooms used by these persons is recommended.
How can I remove scabies mites from my clothes?
Scabies mites do not survive
more than 2-3 days away from human skin. Items such as bedding, clothing, and
towels used by a person with scabies can be decontaminated by machine-washing
in hot water and drying using the hot cycle or by dry-cleaning. Items that
cannot be washed or dry-cleaned can be decontaminated by removing from any body
contact for at least 72 hours.
My spouse and I were diagnosed with scabies. After several treatments,
he/she still has symptoms while I am cured. Why?
The rash and itching of
scabies can persist for several weeks to a month after treatment, even if the
treatment was successful and all the mites and eggs have been killed. Your
health care provider may prescribe additional medication to relieve itching if
it is severe. Symptoms that persist for longer than 2 weeks after treatment can
be due to a number of reasons, including:
· Incorrect diagnosis of
scabies. Many drug reactions can mimic the symptoms of scabies and cause a skin
rash and itching; the diagnosis of scabies should be confirmed by a skin
scraping that includes observing the mite, eggs, or mite feces (scybala) under
a microscope. If you are sleeping in the same bed with your spouse and have not
become reinfested, and you have not retreated yourself for at least 30 days,
then it is unlikely that your spouse has scabies.
· Reinfestation with scabies
from a family member or other infested person if all patients and their
contacts are not treated at the same time; infested persons and their contacts
must be treated at the same time to prevent reinfestation.
· Treatment failure caused by
resistance to medication, by faulty application of topical scabicides, or by
failure to do a second application when necessary; no new burrows should appear
24-48 hours after effective treatment.
· Treatment failure of crusted
scabies because of poor penetration of scabicide into thick scaly skin
containing large numbers of scabies mites; repeated treatment with a
combination of both topical and oral medication may be necessary to treat
crusted scabies successfully.
· Reinfestation from items
(fomites) such as clothing, bedding, or towels that were not appropriately
washed or dry-cleaned (this is mainly of concern for items used by persons with
crusted scabies); potentially contaminated items (fomites) should be machine
washed in hot water and dried using the hot temperature cycle, dry-cleaned, or
removed from skin contact for at least 72 hours.
· An allergic skin rash
(dermatitis); or
· Exposure to household mites
that cause symptoms to persist because of cross-reactivity between mite
antigens.
If itching continues more than 2-4 weeks or if new burrows or rash
continue to appear, seek the advice of a physician; retreatment with the same
or a different scabicide may be necessary.
If I come
in contact with a person who has scabies, should I treat myself?
No. If a person thinks he or
she might have scabies, he/she should contact a doctor. The doctor can examine
the person, confirm the diagnosis of scabies, and prescribe an appropriate
treatment. Products used to treat scabies in humans are available only with a
doctor’s prescription.
Sleeping with or having sex
with any scabies infested person presents a high risk for transmission. The
longer a person has skin-to-skin exposure, the greater is the likelihood for
transmission to occur. Although briefly shaking hands with a person who has
non-crusted scabies could be considered as presenting a relatively low risk,
holding the hand of a person with scabies for 5-10 minutes could be considered
to present a relatively high risk of transmission. However, transmission can
occur even after brief skin-to-skin contact, such as a handshake, with a person
who has crusted scabies. In general, a person who has skin-to-skin contact with
a person who has crusted scabies would be considered a good candidate for
treatment.
To determine when prophylactic
treatment should be given to reduce the risk of transmission, early
consultation should be sought with a health care provider who understands:
1. the type of scabies (i.e.
non-crusted vs crusted) to which a person has been exposed;
2. the degree and duration of
skin exposure that a person has had to the infested patient;
3. whether the exposure occurred
before or after the patient was treated for scabies; and,
4. whether the exposed person
works in an environment where he/she would be likely to expose other people
during the asymptomatic incubation period. For example, a nurse or caretaker
who works in a nursing home or hospital often would be treated prophylactically
to reduce the risk of further scabies transmission in the facility.
From CDC
