Scabies

Definition

Scabies is a relatively contagious infection caused by a tiny mite.

Description

Scabies is caused by a tiny, 0.3 mm long insect called a mite. When a human comes in contact with the female mite, the mite burrows under the skin, laying eggs along the line of its burrow. These eggs hatch, and the resulting offspring rise to the surface of the skin, mate,

and repeat the cycle either within the skin of the original host, or within the skin of its next victim.

The intense itching almost always caused by scabies is due to a reaction within the skin to the feces of the mite. The first time someone is infected with scabies, he or she may not notice any itching for a number of weeks (four to six weeks). With subsequent infections, the itchiness will begin within hours of picking up the first mite.

— Rosalyn Carson-DeWitt, MD

Dictionary: sca·bies  (skā'bēz)

1. A contagious skin disease caused by a parasitic mite (Sarcoptes scabiei) and characterized by intense itching.
2. A similar disease in animals, especially sheep.

[Middle English, from Latin scabiēs, from scabere, to scratch.]

A contagious disease caused by Sarcoptes scabiei, the itch mite, characterized by intense itching of the skin.

Scabies. (Zitelli/Davis, 2002)

Definition

Scabies, also known as sarcoptic acariasis, is a contagious, parasitic skin infection caused by a tiny mite (sarcoptes scabiei).

Description

Scabies is caused by a tiny, 0.3 mm-long, parasitic insect called a mite. When a human comes into contact with the female mite, the mite burrows under the skin, laying eggs along the lines of its burrow. These eggs hatch, and the resulting offspring rise to the surface of the skin; mate; and repeat the cycle either within the skin of the original host; or within the skin of its next victim, causing red lesions.

The intense itching, or pruritus, that is almost always caused by scabies is due to a reaction within the skin to the feces of the mite. The first time someone is infected with scabies, he or she may not notice any itching for four to six weeks. With subsequent infections, the itchiness will begin within hours of picking up the first mite.

Causes & Symptoms

Scabies is most common among people who live in overcrowded conditions, and whose ability to practice good hygiene is limited. Scabies can be passed between people by close skin contact. Although the mites can only live away from human skin for about three days, sharing clothing or bedclothes can pass scabies among family members or close contacts. In May 2002, the Centers for Disease Control (CDC) included scabies in its updated guidelines for the treatment of sexually transmitted diseases.

Mite burrows within the skin are seen as winding, slightly raised gray lines along a person's skin. The female mite may be found at one end of the burrow, as a tiny pearl-like bump underneath the skin. Because of the intense itching, burrows may be obscured by scratch marks left by the patient. The most common locations for burrows include the sides of the fingers, between the fingers, the top of the wrists, around the elbows and armpits, around the nipples of the breasts in women, in the genitalia of men, around the waist (beltline), and on the lower part of the buttocks. Babies may have burrows on the soles of their feet, palms of their hands, and faces. The itching from scabies becomes worse after a hot shower and at night. Scratching, however, seems to serve some purpose in scabies, as the mites are apparently often inadvertently removed. Most infestations with scabies are caused by no more than 15 mites altogether.

Infestation with huge numbers of mites (on the order of thousands to millions) occurs when an individual does not scratch, or when an individual has a weakened immune system. These patients include those who live in institutions; are mentally retarded, or physically infirm; have other diseases which affect the amount of sensation they have in their skin (leprosy or syringomyelia); have leukemia or diabetes; are taking medications that lower their immune response (cancer chemotherapy, drugs given after organ transplantation); or have other diseases which lower their immune response (such as acquired immunodeficiency syndrome or AIDS). This form of scabies, with its major infestation, is referred to as crusted scabies or Norwegian scabies. Infected patients have thickened crusty areas all over their bodies, including over the scalp. Their skin appears scaly, and their fingernails may be thickened and horny.

Diagnosis

Diagnosis can be made simply by observing the characteristic burrows of the mites causing scabies. A sterilized needle can be used to explore the pearly bump at the end of a burrow, remove its contents, and place it on a slide to be examined. The mite itself may then be identified under a microscope.

Occasionally, a type of mite carried on dogs (Sarcoptes scabiei var. canis) may infect humans. These mites cannot survive for very long on humans, however, so the infection is less severe.

Treatment

A paste made from two herbs, neem (Azadirachta indica) and turmeric (Curcuma longa,) applied to the affected area daily for 15 days has been found to be effective in treating scabies.

Allopathic Treatment

Several types of lotions (usually containing 5% permethrin) can be applied to the body and left on for 12–24 hours. One topical application is usually sufficient, although the scabicide may be reapplied after a week if mites remain. Preparations containing lindane are no longer recommended for treating scabies as of 2003 because of the potential for damage to the nervous system. Itching can be lessened by the use of calamine lotion or antihistamine medications.

In addition to topical medications, the doctor may prescribe oral ivermectin. Ivermectin is a drug that was originally developed for veterinary practice as a broad-spectrum antiparasite agent. Studies done in humans, however, have found that ivermectin is as safe and effective as topical medications for treating scabies. A study published in 2003 reported that ivermectin is safe for people in high-risk categories, including those with compromised immune systems.

Expected Results

The prognosis for complete recovery from a scabies infestation is excellent. In patients with weak immune systems, the biggest danger is that the areas of skin involved with scabies will become secondarily infected with bacteria.

Prevention

Good hygiene is essential in the prevention of scabies. When a member of a household is diagnosed with scabies, all that person's recently worn clothing and bedding should be washed in very hot water. Extensive cleaning of the household, however, is not necessary because the mite does not live long away from the human body.

Resources

Books

Darmstadt, Gary L., and Al Lane. "Arthropod Bites and Infestations." In Nelson Textbook of Pediatrics, edited by Richard Behrman. Philadelphia: W.B. Saunders Co., 1996.

Maguire, James H. "Ectoparasite Infestations and Arthropod Bites and Stings." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw–Hill, 1998.

"Scabies (The Itch)." Section 10, Chapter 114 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002.

Stoffman, Phyllis. The Family Guide to Preventing and Treating 100 Infectious Diseases. New York: John Wiley and Sons, Inc., 1995.

Periodicals

Burroughs, R. F., and D. M. Elston. "What's Eating You? Canine Scabies." Cutis 72 (August 2003): 107–109.

Burstein, G. R., and K. A. Workowski. "Sexually Transmitted Diseases Treatment Guidelines." Current Opinion in Pediatrics 15 (August 2003): 391–397.

Fawcett, R. S. "Ivermectin Use in Scabies." American Family Physician 68 (September 15, 2003): 1089–1092.

Santoro, A. F., M. A. Rezac, and J. B. Lee. "Current Trend in Ivermectin Usage for Scabies." Journal of Drugs in Dermatology 2 (August 2003): 397–401.

Organizations

American Academy of Dermatology (AAD). 930 East Woodfield Road, Schaumburg, IL 60173. (847) 330-0230. .

[Article by: Kathleen D. Wright; Rebecca J. Frey, PhD]

Definition

Scabies is a relatively contagious infection caused by a tiny mite called Sarcoptes scabiei.

Description

Scabies is caused by a tiny insect about 0.3 mm long called a mite. When a human comes in contact with the female mite, the mite burrows under the skin, laying eggs along the line of its burrow. These eggs hatch, and the resulting offspring rise to the surface of the skin, mate, and repeat the cycle either within the skin of the original host or within the skin of its next victim.

The intense itching almost always caused by scabies is due to a reaction within the skin to the feces of the mite. The first time someone is infected with scabies, he or she may not notice any itching for a number of weeks (four to six weeks). With subsequent infections, the itchiness begins within hours of picking up the first mite.

Demographics

Prevalence rates are not clear; some studies suggest that between 6 and 27 percent of the population have scabies at any one time. Scabies is more common among schoolchildren and individuals living in crowded conditions.

Causes and Symptoms

Scabies is most common among people who live in overcrowded conditions and whose ability to practice good hygiene is limited. Scabies can be passed between people by close skin contact. Although the mites can only live away from human skin for about three days, sharing clothing or bedclothes can pass scabies among family members or close contacts. In May 2002, the Centers for Disease Control (CDC) included scabies in its updated guidelines for the treatment of sexually transmitted diseases.

The itching (pruritus) from scabies is worse after a hot shower and at night. Burrows are seen as winding, slightly raised gray lines along the skin. The female mite may be seen at one end of the burrow, as a tiny pearl-like bump underneath the skin. Because of the intense itching, burrows may be obscured by scratch marks left by the patient. The most common locations for burrows are the sides of the fingers, between the fingers, the top of the wrists, around the elbows and armpits, around the nipples of the breasts in women, in the genitalia of men, around the waist (beltline), and on the lower part of the buttocks. Babies may have burrows on the soles of their feet, palms of their hands, and faces.

Scratching seems to serve some purpose in scabies, as the mites are apparently often inadvertently removed. Most infestations with scabies are caused by no more than 15 mites altogether.

Infestation with huge numbers of mites (on the order of thousands to millions) occurs when an individual does not scratch or when an individual has a weakened immune system. These patients include the elderly; those who live in institutions; the mentally retarded or physically infirm; those who have other diseases which affect the amount of sensation they have in their skin (leprosy or syringomyelia); leukemia or diabetes sufferers; those taking medications which lower their immune response (cancer chemotherapy or immunosuppressant drugs given after organ transplantation); or people with other diseases which lower their immune response (such as acquired immunodeficiency syndrome or AIDS). This form of scabies, with its major infestation, is referred to as crusted scabies or Norwegian scabies. Infected patients have thickened, crusty areas all over their bodies, including over the scalp. Their skin is scaly. Their fingernails may be thickened and horny.

Diagnosis

Diagnosis can be made simply by observing the characteristic burrows of the mites causing scabies. A sterilized needle can be used to explore the pearly bump at the end of a burrow, remove its contents, and place it on a slide to be examined. The mite itself may then be identified under a microscope.

Occasionally, a type of mite carried on dogs (Sarcoptes scabiei var. canis) may infect humans. These mites cannot survive for very long on humans, and so the infection is very light.

Treatment

Several types of lotions (usually containing 5% permethrin) can be applied to the body and left on for 12 to 24 hours. One topical application is usually sufficient, although the scabicide may be reapplied after a week if mites remain. Preparations containing lindane are no longer recommended for treating scabies because of the potential for damage to the nervous system. Itching can be lessened by the use of calamine lotion or antihistamine medications.

In addition to topical medications, the doctor may prescribe oral ivermectin, a drug that was originally developed for veterinary practice as a broad-spectrum antiparasite agent. Studies done in humans, however, have found that ivermectin is as safe and effective as topical medications for treating scabies. A study published in 2003 reported that ivermectin is safe for people in high-risk categories, including those with compromised immune systems.

Prognosis

The prognosis for complete recovery from scabies infestation is excellent. In patients with weak immune systems, the biggest danger is that the areas of skin involved with scabies will become secondarily infected with bacteria.

Prevention

Good hygiene is essential in the prevention of scabies. When a member of a household is diagnosed with scabies, all that person's recently worn clothing and bedding should be washed in very hot water.

Parental Concerns

One of the biggest concerns among family members of an individual with scabies is its ready transmissibility. Care should be taken to avoid sharing bedding, towels, and clothing with an infected family member. Some healthcare providers recommend that all family members be treated with a scabicide, whether or not scabies is evident. Linens of all family members should be washed in the hottest water possible to avoid cross-contamination.

Resources

Books

"Arthropod Bites and Infestations." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.

"Infestations and Bites." In Clinical Dermatology, 4th ed. Edited by Thomas P. Habif et al. St. Louis, MO: Mosby, 2004.

"Scabies." In Ferri's Clinical Advisor: Instant Diagnosis and Treatment. Edited by Fred F. Ferri. St. Louis, MO: Mosby, 2004.

Organizations

American Academy of Dermatology (AAD). 930 East Woodfield Road, Schaumburg, IL 60173. Web site: www.aad.org.Web sites "Facts about Scabies." Available online at www.safe2use.com/pests/scabies/scabies.htm (accessed December 30, 2004).

[Article by: Rosalyn Carson-DeWitt, MD Rebecca J. Frey, PhD]

A skin infection caused by a mite, Sarcoptes scabei. The female mite burrows under the skin, particularly around the fingers and genitalia, and lays eggs. Scabies is transmitted by close body contact, especially in crowded and unhygienic places, but the mite is no respecter of social class. Infection does not interfere with physical activity, although it can be transmitted in close contact sports such as wrestling. Treatment is application of a cream that gets rid of the mites. Athletes can return to contact sports the day after the mites have been removed.

Infestation by mites of the genus Sarcoptes. See also sarcoptic mange.

• feline s. — see notoedres cati.
• s. incognito — a variant of sarcoptic mange in dogs in which mites are difficult or impossible to recover in skin scrapings, presumably because of the extensive grooming and generally high level of skin hygiene that lacks only the use of a scabicide. Also there are usually only a few mites present once an immunity develops. Further infection may cause a hypersensitivity but the mites present will still be in small numbers.
• Norwegian s. — a variety characterized by immense numbers of mites and marked scaling of the skin. Seen in immunocompromised patients.

This article is about scabies in humans. For scabies in dogs, see mange.

Scabies
Classification & external resources

ICD-10	B86.
ICD-9	133.0
DiseasesDB	11841

Sarcoptes scabiei var canis

Scabies is a transmissible ectoparasite skin infection characterized by superficial burrows, intense pruritus (itching) and secondary infection. The word scabies comes from the Latin word for "scratch" (scabere).

Etiology

Scabies is caused by the mite Sarcoptes scabiei, variety hominis, as shown by the Italian biologist Diacinto Cestoni in the 18th century. It produces intense, itchy skin rashes when the impregnated female tunnels into the stratum corneum of the skin and deposits eggs in the burrow. The larvae, which hatch in 3-10 days, move about on the skin, molt into a "nymphal" stage, and then mature into adult mites. The adult mites live 3-4 weeks in the host's skin.

The action of the mites moving within the skin and on the skin itself produces an intense itch which may resemble an allergic reaction in appearance. The presence of the eggs produces a massive allergic response which, in turn, produces more itching.

Scabies is transmitted readily, often throughout an entire household, by skin-to-skin contact with an infected person (e.g. bed partners, schoolmates, daycare), and thus is sometimes, although inaccurately, classed as a sexually transmitted disease. Spread by clothing, bedding, or towels is a less significant risk, though possible.

Onset

It takes approximately 4-6 weeks to develop symptoms after initial infestation. Therefore, a person may have been contagious for at least a month before being diagnosed. This means that person might have passed scabies to anyone at that time with whom they had close contact. Someone who sleeps in the same room with a person with scabies has a high possibility of having scabies as well, although they may not show symptoms.

The symptoms are caused by an allergic reaction that the body develops over time to the mites and their by-products under the skin, thus the 4-6 week "incubation" period. There are usually relatively few mites on a normal, healthy person — about 11 females in burrows. Scabies are microscopic although sometimes they are visible as a pinpoint of white. The females burrow into the skin and lay eggs there. Males roam on top of the skin, however, they can and do occasionally burrow. Both males and females surface at times, especially at night. They can be washed or scratched off (however scratching should be done with a washcloth to avoid cutting the skin as this can lead to infection), which, although not a cure, helps to keep the total population low. Also, humans create antibodies to the scabies mites which do kill some of them.

Signs, symptoms, and diagnosis

A scabies burrow under magnification. The scaly patch at the left is due to scratching of the original papule. The mite traveled from there to the upper right, where it can be seen as a dark spot at the end of the burrow.

A delayed hypersensitivity (allergic) response resulting in a papular eruption (red, elevated area on skin) often occurs 30-40 days after infestation. While there may be hundreds of papules, fewer than 10 burrows are typically found. The burrow appears as a fine, wavy and slightly scaly line a few millimeters to one centimeter long. A tiny mite (0.3 to 0.9.08 mm) may sometimes be seen at the end of the burrow. Most burrows occur in the webs of fingers, flexing surfaces of the wrists, around elbows and armpits, the areolae of the breasts in females and on genitals of males, along the belt line, and on the lower buttocks. The face usually does not become involved in adults.

The rash may become secondarily infected; scratching the rash may break the skin and make secondary infection more likely. In persons with severely reduced immunity, such as those with HIV infection, or people being treated with immunosuppressive drugs like steroids, a widespread rash with thick scaling may result. This variety of scabies is called Norwegian scabies.

Scabies is frequently misdiagnosed as intense pruritus (itching of healthy skin) before papular eruptions form. Upon initial pruritus the burrows appear as small, barely noticeable bumps on the hands and may be slightly shiny and dark in color rather than red. Initially the itching may not exactly correlate to the location of these bumps. As the infestation progresses, these bumps become more red in color.

Generally diagnosis is made by finding burrows, which often may be difficult because they are scarce, because they are obscured by scratch marks, or by secondary dermatitis (unrelated skin irritation). If burrows are not found in the primary areas known to be affected, the entire skin surface of the body should be examined.

The suspicious area can be rubbed with ink from a fountain pen or alternately a topical tetracycline solution which will glow under a special light. The surface is then wiped off with an alcohol pad; if the person is infected with scabies, the characteristic zigzag or S pattern of the burrow across the skin will appear.

When a suspected burrow is found, diagnosis may be confirmed by microscopy of surface scrapings, which are placed on a slide in glycerol, mineral oil or immersion in oil and covered with a coverslip. Avoiding potassium hydroxide is necessary because it may dissolve fecal pellets. Positive diagnosis is made when the mite, ova, or fecal pellets are found.

Evolution of a scabies infection on a woman.	Day 3 of scabies	Day 4 of scabies	Day 6 of scabies
Day 7 of scabies	The disease was diagnosed on day 8, and treatment with a pesticide lotion began on the same day.	Day 8 of scabies (treatment begins)	Day 11 of scabies (under treatment)
Day 12 of scabies (under treatment)	Day 13 of scabies (under treatment)	Scarless healing

Scabies in animals

Puppy with Scabies (Sarcoptic mange)

Many domestic animals have their own species of Sarcoptes mites, and all can transiently affect humans.^[1][2] The most frequently diagnosed form is Sarcoptic mange in dogs. In dogs and other animals, scabies produces severe itching and secondary skin infections. Affected animals often lose weight and become unthrifty.

Compromised immune systems

People with compromised immune systems may not develop antibodies to the mites and may develop crusted Norwegian scabies. In this case, many form scabs or develop very red skin especially in the elderly and the mentally handicapped where white or gray crusted areas develop with little itching and little or no red bumps and mite population numbers soar to hundreds, thousands, or millions in AIDS patients ^{[citation needed]}. These cases require additional treatment options to ensure a complete kill. Ivermectin is the treatment of choice in these patients combined with any other topical treatment.

Scabies on the Foot

Scabies on the Arm

Scabies on the Hand

Scabies of the Finger

Treatment

The neutrality of this section is disputed. Please see the discussion on the talk page.

Medications

Expect increased itching and red bumps for the first week after taking any medication for scabies. The dead mites remain in the skin for 30 days. They are removed with the body's natural shedding process. During those 30 days expect new bumps and itching.

The following agents have been used in the treatment of scabies:

Oral

1. Ivermectin (Stromectol): Broad spectrum anti-parasite medication. Newest scabies treatment. Safer than other alternatives and is the easiest and quickest to use. [1]

A single dose of ivermectin (dosing: 200 µg/kg) has been reported to cure, but is an off-label use; some authorities recommend repeating treatment at 14 days.

Topical

^[1]

1. Crotamiton (except to eyes, nose, mouth), 25% benzyl benzoate cream or lotion.
2. Malathion: Common pesticide, nervous system toxin in high quantities, no known mutagenic or carcinogenic properties in humans have been confirmed.[2]
3. Permethrin: Another pesticide, lacks carcinogenic and teratogenic testing in humans although animal tests showed no signs of carcinogenic or teratogenic effects. Toxicity may resemble allergic reactions. [3]
4. Crotamiton (Eurax): Less toxic, but less effective. Must use for roughly 3 days. [4]
5. Benzyl benzoate: Less toxic, but can cause asthmatic and allergic reactions. Must use for a week on 1st, 4th, and 7th day.^{[citation needed]}
6. 10% sulfur ointment: Can be used in pregnant women and infants under two months of age. It is available over-the-counter.
7. Lindane: (Kwell, Kwellada). For use with patients where permethrin use is contraindicated.[5]

Lindane has been used in the past to treat both scabies and lice. While infrequent, serious side effects have occurred when using lindane and is therefore considered a treatment option of last resort [6]. Lindane is no longer available in the UK or Australia, but is still available in the U.S.. Lindane is readily absorbed through the skin if the shower to wash it off is too hot. Similarly, 5–10% sulfur ointments are considered historical.

Preventing Reinfection

All family and close contacts should be treated at the same time, even if asymptomatic. After treatment has been applied or taken, (or directly before treatment if you are careful and wear gloves) cleaning of environment should occur. A person can easily be reinfected with scabies.

Without a host, scabies mites can on average survive up to 48-72 hours away from human skin. [7] As in cases of Crusted Scabies, they can survive much longer, up to 7 days. Therefore it is recommended, after treatment, to wash all material (such as clothes, bedding, and towels) that has been in contact with all infested persons in the last three days.

All household members should be treated at the same time and cleaning must be thorough and simultaneous. Either isolate long enough for the mites to die in a plastic bag for at least 1 week, or clean or freeze overnight.

• Vacuuming floors, carpets, and rugs.
• Disinfecting floor and bathroom surfaces by mopping (this only needs to be done after the first treatment).
• Daily washing of recently worn clothes, towels and bedding in hot water and drying in a hot dryer.
• Hot drying pillows for 30 minutes.
• Overnight freezing, in a plastic bag: stuffed animals, brushes, combs, shoes, coats, gloves, hats, robes, wetsuits, etc.
• Quarantine in a plastic bag for two weeks: things that cannot be washed, hot dried, frozen or drycleaned.
• Drycleaning: things that cannot be washed, hot dried or frozen or quarantined.

Treatment for Pets

Pets and humans get infected with different types of mites. The mites that we get can not survive and reproduce on pets.

Itchiness During Treatment

Options to combat itchiness include antihistamines such as cetirizine. Prescription: Doxepin (Sinequan - oral or Zonalon - topical).

References

• Center for Disease Control
• The Merck Manual of Diagnosis and Therapy, 17th edition, 1999
• Clinician's Pocket Reference, 9th edition, 2002
• Taber's Cyclopedic Medical Dictionary, 17th edition, 1993
• United States Centers for Disease Control and Protection
• World Health Organization Essential Medicines Library
• American Social Health Association
• Chosidow O. "Scabies". New Engl J Med 354 (16): 1718–1727. 
• MedlinePlus Drug Information: Lindane

Numbered references

1. ^ Topical (surface) medications are often effective and should be applied thoroughly to all skin from the neck down, especially to areas known to be primarily affected (skin folds, hands, etc.). The topical medication of choice is 5% permethrin because it is safe for all age groups.Scheinfeld NS (2004). "Controlling scabies in institutional settings: a review of medications, treatment models, and implementation.". Amer J Clin Dermatol 5 (1): 31-7. 

External links

Pediculosis, acariasis and other infestations (B85-B89, 132-134)
Pediculosis - Phthiriasis - Scabies - Myiasis

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - fnat, scabies

Nederlands (Dutch)
schurft

Français (French)
n. - gale

Deutsch (German)
n. - Krätze

Ελληνική (Greek)
n. - (παθολ.) ψώρα

Italiano (Italian)
scabbia

Português (Portuguese)
n. - sarna (f) (Med.)

Русский (Russian)
чесотка

Español (Spanish)
n. - sarna

Svenska (Swedish)
n. - skabb

中文（简体） (Chinese (Simplified))
疥疮

中文（繁體） (Chinese (Traditional))
n. - 疥瘡

한국어 (Korean)
n. - 개선, 옴

日本語 (Japanese)
n. - 疥癬

العربيه (Arabic)
‏(الاسم) ألجرب‏

עברית (Hebrew)
n. - ‮גרדת, גרבת‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.