Scabies
A tiny mite has infested humans for at least 2,500 years. It is
often hard to detect and causes a fierce, itchy skin condition known as scabies.
Dermatologists estimate that more than 300 million cases of scabies occur
worldwide every year. The condition can strike anyone of any race or age,
regardless of personal hygiene. But there is good news: with better detection
methods and treatments, scabies need not cause more than temporary distress.
More than an Itch: How Scabies Develops
The microscopic mite that causes scabies can barely be seen by the human eye. A
tiny, eight-legged creature with a round body, the mite burrows within the skin.
Within several weeks the patient develops an allergic reaction. This results in
severe itching, often intense enough to keep sufferers awake all night.
Human scabies is almost always caught from another person by close contact - it
could be a child, a friend, or another family member. Dermatologists, who
frequently treat patients with scabies, point out that scabies is not a
condition only of low-income families, neglected children, or poor hygiene.
Although, more prominent in crowded living conditions, and poor hygiene -
everyone is susceptible.
Scabies skin mite is about 0.4mm, just visible to the human eye
Attracted to warmth and odor, the female mite burrows into the skin, lays eggs,
and produces secretions that cause allergic reactions. Larvae, or newly hatched
mites, travel to the skin surface, lying in shallow pockets where they will
develop into adult mites. If the mite is scratched off the skin, it can live in
bedding up to 24 hours. It may be up to a month before a newly infested person
will notice the itching, especially in people with good hygiene and who bathe
regularly.
What to Look for
The earliest and most common symptom of scabies is itching, especially at night.
Early on, little red bumps, like hives, tiny bites, or pimples appear. In more
advanced cases, the skin may be crusty or scaly.
Scabies prefers warmer sites on the skin such as skin folds where clothing is
tight. These areas include between the fingers, on the elbows or wrists,
buttocks or belt line, around the nipples, and on the penis. Mites also tend to
hide in, or on, the skin under rings, bracelets or watchbands, or under the
nails. In children, the infestation may involve the entire body, including the
palms, soles, and scalp. The child may be tired and irritable as a result of
loss of sleep from itching or scratching all night long.
Bacterial infection may occur secondarily with scabies due to scratching. In
many cases, children are treated because of infected skin lesions rather than
for the scabies itself. Although treatment of bacterial infections sometimes
provides relief, recurrence is almost certain if the scabies infection is not
treated.
Crusted Scabies
Crusted scabies is a form of the disease in which the symptoms are far more
severe than usual. Large areas of the body, including hands and feet, may be
scaly and crusted. These crusts hide thousands of live mites and their eggs,
making treatment difficult because medications applied directly to the skin may
not be able to penetrate the thickened skin. This type of scabies occurs mostly
among the elderly, in some AIDS patients, or in people whose immunity is
decreased. These cases are extremely infectious.
Diagnosis
A thorough head-to-toe examination in good lighting, with careful attention to
skin crevices, will usually be recommended and performed at your dermatologist's
office.
Scabies masquerading as contact dermatitis
Many cases of scabies can be diagnosed by dermatologists without special tests.
To confirm scabies your dermatologist can perform a painless test that involves
applying a drop of oil to the suspected lesion. The site is then scraped and
transferred to a glass slide which is then examined using a microscope. A
diagnosis is made by finding scabies mites or their eggs.
Who is most at risk?
Scabies is most common in those who have close physical contact with others,
particularly children, mothers of young children, and elderly people in nursing
homes.
All in the family - Studies of families have shown that children under two years
of age are most at risk, followed by mothers and older female siblings, and then
by other family members who have frequent and close physical contact.
Scabies on sole of child's foot
Among the elderly - Scabies among resident patients of nursing homes and
extended care facilities has become a common problem due to delayed diagnosis
since it can often be mistaken for other skin conditions. The delay allows time
for scabies to spread to nursing home staff and other residents. Because
residents require assistance in daily living activities, this intimate exposure
provides an opportunity for the scabies mite to spread.
Getting Rid of Scabies
Scabies is easy and quick to treat with prescription drugs: 5 percent permethrin
cream is applied to the skin from head-to-toe at bedtime, and washed off the
next morning. Dermatologists recommend that the cream be applied to cool, dry
skin, over the entire body (including the palms of the hands, soles of the feet,
groin, under finger nails, and the scalp in small children) and left on for 8 to
14 hours. A second treatment one week later may be recommended for infants with
scabies of the palms and soles, or if new lesions appear after treatment. The
only reported side effect of 5 percent permethrin cream is a mild, temporary
burning and stinging, particularly in bad cases of scabies. All lesions should
be healed within four weeks after the treatment. If a patient continues to have
trouble, he or she may be getting reinfested and require further evaluation and
treatment by a dermatologist.
Another effective prescription treatment is 1 percent lindane lotion. Also an
overnight treatment, lindane is effective after 1 to 2 doses. Patients using
lindane are instructed to wash the lotion off after 8 to 12 hours, not to exceed
recommended doses, and to avoid a second treatment within a 7-day period.
Lindane should not be used on infants, small children, pregnant or nursing
women, or people with seizures or other neurological diseases.
Sulfur ointment and Crotamiton cream are other special care treatment options.
(Note: Antihistamines may be prescribed to relieve itching, which can last for
weeks.)
Umbilical and waistline lesions
Ivermectin is an oral medicine which may be prescribed for certain cases of
scabies, especially the difficult to treat crusted form. Like lindane, it is not
for use by infants or pregnant women.
The critical factor in the treatment of scabies is getting rid of the mite. Each
individual in the family or group, whether itching or not, should be treated.
The entire community at risk must be treated to stop an epidemic of scabies.
In a family, all members should be treated at the same time, as well as others
who are in close contact, such as close friends, and sometimes day care or
school classmates. Scabies in institutions can be kept to manageable levels by
routinely examining patients and conducting thorough skin exams of all new
residents. The most successful, cost-effective approach is to treat all patients
and health care personnel at the same time. Bedding and clothing must be washed
or dry-cleaned.
Successful eradication of this infestation requires the following:
