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63-433: Scabies ( / ˈ s k eɪ b iː z , ˈ s k eɪ b i iː z / ; also sometimes known as the seven-year itch ) is a contagious human skin infestation by the tiny (0.2–0.45 mm) mite Sarcoptes scabiei , variety hominis . The word is from Latin : scabere , lit.   'to scratch'. The most common symptoms are severe itchiness and a pimple -like rash. Occasionally, tiny burrows may appear on

126-410: A poor immune system ; the number of mites also makes them much more contagious. In these cases, spread of infection may occur during brief contact or by contaminated objects. The mite is very small and at the limit of detection with the human eye. It is not readily obvious; factors that aid in detection are good lighting, magnification, and knowing what to look for. Diagnosis is based either on detecting

189-406: A " nymphal " stage, before maturing as adults, which live three to four weeks in the host's skin. Males roam on top of the skin, occasionally burrowing into the skin. In general, the total number of adult mites infesting a healthy hygienic person with non-crusted scabies is small, about 11 females in burrows, on average. The movement of mites within and on the skin produces an intense itch, which has

252-487: A description consistent with scabies. Arab physician Ibn Zuhr is believed to have been the first to provide a clinical description of the scabies mites. Roman encyclopedist and medical writer Aulus Cornelius Celsus ( circa 25 BC – 50 AD) is credited with naming the disease "scabies" and describing its characteristic features. The parasitic etiology of scabies was documented by Italian physician Giovanni Cosimo Bonomo (1663–1696) in his 1687 letter, "Observations concerning

315-404: A few days after mites are eradicated. Nodular lesions from scabies may continue to be symptomatic for weeks after the mites have been killed. Rates of scabies are negatively related to temperature and positively related to humidity. Scabies may be diagnosed clinically in geographical areas where it is common when diffuse itching presents along with either lesions in two typical spots or itchiness

378-410: A higher treatment failure rate than topical permethrin. Another review found that oral ivermectin provided a reasonable balance between efficacy and safety. A study has demonstrated that scabies is markedly reduced in populations taking ivermectin regularly; the drug is widely used for treating scabies and other parasitic diseases particularly among the poor and disadvantaged in the tropics, beginning with

441-412: A number of populations. No vaccine is available for scabies. The simultaneous treatment of all close contacts is recommended, even if they show no symptoms of infection ( asymptomatic ), to reduce rates of recurrence. Since mites can survive for only two to three days without a host, other objects in the environment pose little risk of transmission except in the case of crusted scabies. Therefore, cleaning

504-476: A period of about 48 days. Keratinocyte differentiation throughout the epidermis is in part mediated by a calcium gradient, increasing from the stratum basale until the outer stratum granulosum, where it reaches its maximum, and decreasing in the stratum corneum. Calcium concentration in the stratum corneum is very low in part because those relatively dry cells are not able to dissolve the ions. This calcium gradient parallels keratinocyte differentiation and as such

567-411: A rate of 30 - 90 milligrams of skin flakes every hour, or 0.720 - 2.16 grams per day. Epidermal development is a product of several growth factors , two of which are: The epidermis serves as a barrier to protect the body against microbial pathogens, oxidant stress ( UV light ), and chemical compounds, and provides mechanical resistance to minor injury. Most of this barrier role is played by

630-708: Is a fatal disease of wombats. Scabies is also a concern for cattle . The International Alliance for the Control of Scabies was started in 2012, and brings together over 150 researchers, clinicians, and public-health experts from more than 15 countries. It has managed to bring the global health implications of scabies to the attention of the World Health Organization (WHO). Consequently, the WHO has included scabies on its official list of neglected tropical diseases and other neglected conditions. Moxidectin

693-530: Is being evaluated as a treatment for scabies. It is established in veterinary medicine to treat a range of parasites, including sarcoptic mange. Its advantage over ivermectin is its longer half-life in humans, thus potential duration of action. Tea tree oil (TTO) exhibits scabicidal action in a laboratory setting. Infestation Too Many Requests If you report this error to the Wikimedia System Administrators, please include

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756-566: Is considered a key regulator in the formation of the epidermal layers. Elevation of extracellular calcium concentrations induces an increase in intracellular free calcium concentrations. Part of that intracellular increase comes from calcium released from intracellular stores and another part comes from transmembrane calcium influx, through both calcium-sensitive chloride channels and voltage-independent cation channels permeable to calcium. Moreover, it has been suggested that an extracellular calcium-sensing receptor (CaSR) also contributes to

819-503: Is endemic in many developing countries, where it tends to be particularly problematic in rural and remote areas. In such settings, community-wide control strategies are required to reduce the rate of disease, as treatment of only individuals is ineffective due to the high rate of reinfection. Large-scale mass drug administration strategies may be required where coordinated interventions aim to treat whole communities in one concerted effort. Although such strategies have shown to be able to reduce

882-482: Is known as sarcoptic mange , and is typically caused by slightly different but related mites. The characteristic symptoms of a scabies infection include intense itching and superficial burrows. Because the host develops the symptoms as a reaction to the mites' presence over time, typically a delay of four to six weeks occurs between the onset of infestation and the onset of itching. Similarly, symptoms often persist for one to several weeks after successful eradication of

945-452: Is not recommended for children under six years of age. Topical ivermectin preparations have been shown to be effective for scabies in adults. It has also been useful for sarcoptic mange , the veterinary analog of human scabies. One review found that the efficacy of permethrin is similar to that of systemic or topical ivermectin. A separate review found that although oral ivermectin is usually effective for treatment of scabies, it does have

1008-460: Is of little importance. Rooms used by those with crusted scabies require thorough cleaning. Several medications are effective in treating scabies. Treatment should involve the entire household, and any others who have had recent, prolonged contact with the infested individual. In addition to treating the infestation, options to control itchiness include antihistamines and prescription anti-inflammatory agents. Bedding, clothing and towels used during

1071-443: Is one of the three most common skin disorders in children, along with ringworm and bacterial skin infections . As of 2015, it affects about 204 million people (2.8% of the world population). It is equally common in both sexes. The young and the old are more commonly affected. It also occurs more commonly in the developing world and tropical climates . Other animals do not spread human scabies; similar infection in other animals

1134-539: Is one of the three most common skin disorders in children, along with tinea and pyoderma . As of 2010, it affects about 100 million people (1.5% of the population) and its frequency is not related to gender. The mites are distributed around the world and equally infect all ages, races, and socioeconomic classes in different climates. Scabies is more often seen in crowded areas with unhygienic living conditions. Globally as of 2009, an estimated 300 million cases of scabies occur each year, although various parties claim

1197-424: Is present in another household member. The classical sign of scabies is the burrow made by a mite within the skin. To detect the burrow, the suspected area is rubbed with ink from a fountain pen or a topical tetracycline solution, which glows under a special light. The skin is then wiped with an alcohol pad. If the person is infected with scabies, the characteristic zigzag or S pattern of the burrow will appear across

1260-645: Is sarcoptic mange, caused by the subspecies Sarcoptes scabiei canis , most commonly in dogs and cats. Sarcoptic mange is transmissible to humans who come into prolonged contact with infested animals, and is distinguished from human scabies by its distribution on skin surfaces covered by clothing. Scabies-infected domestic fowl develop what is known as "scaly leg". Domestic animals that have gone feral and have no veterinary care are frequently affected by scabies. Nondomestic animals have also been observed to develop scabies. Gorillas, for instance, are known to be susceptible to infection by contact with items used by humans, and it

1323-469: Is thought to explain the observed far more rapid allergic skin response to reinfection seen in persons who have been infected previously, especially within the previous year or two. Scabies is contagious and can be contracted through prolonged physical contact with an infested person. This includes sexual intercourse , although a majority of cases are acquired through other forms of skin-to-skin contact. Less commonly, scabies infestation can happen through

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1386-500: The British Medical Journal in 1945. In the 1995 documentary Anne Frank Remembered , Bloeme Evers-Emden told of how she was selected from Auschwitz and sent to a work camp where conditions were sufficiently improved that she was able to survive until the liberation. She said Anne Frank was rejected for this transfer because she had contracted scabies. Scabies may occur in a number of domestic and wild animals;

1449-435: The area of the finger webs, feet, ventral wrists, elbows, back, buttocks, and external genitals. Except in infants and the immunosuppressed, infection generally does not occur in the skin of the face or scalp. The burrows are created by excavation of the adult mite in the epidermis . Acropustulosis , or blisters and pustules on the palms and soles of the feet, are characteristic symptoms of scabies in infants. In most people,

1512-563: The basal layer. The thickness of the epidermis varies from 31.2μm for the penis to 596.6μm for the sole of the foot with most being roughly 90μm. Thickness does not vary between the sexes but becomes thinner with age. The human epidermis is an example of epithelium , particularly a stratified squamous epithelium . The word epidermis is derived through Latin from Ancient Greek epidermis , itself from Ancient Greek epi  'over, upon' and from Ancient Greek derma  'skin'. Something related to or part of

1575-461: The burden of scabies in these kinds of communities, debate remains about the best strategy to adopt, including the choice of drug. The resources required to implement such large-scale interventions in a cost-effective and sustainable way are significant. Furthermore, since endemic scabies is largely restricted to poor and remote areas, it is a public health issue that has not attracted much attention from policy makers and international donors. Scabies

1638-455: The characteristics of a delayed cell-mediated inflammatory response to allergens. IgE antibodies are present in the serum and the site of infection, which react to multiple protein allergens in the body of the mite. Some of these cross-react to allergens from house dust mites . Immediate antibody-mediated allergic reactions (wheals) have been elicited in infected persons, but not in those not infected; immediate hypersensitivity of this type

1701-489: The crusts protect the mites from topical miticides/scabicides, necessitating prolonged treatment of these areas. In the 18th century, Italian biologists Giovanni Cosimo Bonomo and Diacinto Cestoni (1637–1718) described the mite now called Sarcoptes scabiei , variety hominis , as the cause of scabies. Sarcoptes is a genus of skin parasites and part of the larger family of mites collectively known as scab mites. These organisms have eight legs as adults, and are placed in

1764-431: The details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 218814480 Upstream caches: cp1108 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 07:44:46 GMT Epidermis (skin) The epidermis is composed of multiple layers of flattened cells that overlie a base layer ( stratum basale ) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in

1827-514: The developer Merck providing the drug at no cost to treat onchocerciasis from 1987. Other treatments include lindane , benzyl benzoate , crotamiton , malathion , and sulfur preparations. Lindane is effective, but concerns over potential neurotoxicity have limited its availability in many countries. It is banned in California , but may be used in other states as a second-line treatment. Sulfur ointments or benzyl benzoate are often used in

1890-472: The developing world due to their low cost; Some 10% sulfur solutions have been shown to be effective, and sulfur ointments are typically used for at least a week, though many people find the odor of sulfur products unpleasant. Crotamiton has been found to be less effective than permethrin in limited studies. Crotamiton or sulfur preparations are sometimes recommended instead of permethrin for children, due to concerns over dermal absorption of permethrin. Scabies

1953-441: The disease may occur even if the person has not developed symptoms yet. Crowded living conditions, such as those found in child-care facilities, group homes, and prisons, increase the risk of spread. Areas with a lack of access to water also have higher rates of disease. Crusted scabies is a more severe form of the disease, not essentially different but an infestation by very large numbers of mites that typically only affects those with

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2016-569: The elderly, and the immunocompromised. Symptoms typically appear two to six weeks after infestation for individuals never before exposed to scabies. For those having been previously exposed, the symptoms can appear within several days after infestation. However, symptoms may appear after several months or years. The elderly, disabled, and people with impaired immune systems , such as those with HIV/AIDS, cancer, or those on immunosuppressive medications , are susceptible to crusted scabies (also called Norwegian scabies). On those with weaker immune systems,

2079-402: The epidermal cells are of the adherens junction type, formed by transmembrane proteins called cadherins . Inside the cell, the cadherins are linked to actin filaments. In immunofluorescence microscopy, the actin filament network appears as a thick border surrounding the cells, although the actin filaments are actually located inside the cell and run parallel to the cell membrane. Because of

2142-458: The epidermis is maintained by cell division within the stratum basale. Differentiating cells delaminate from the basement membrane and are displaced outward through the epidermal layers, undergoing multiple stages of differentiation until, in the stratum corneum, losing their nucleus and fusing to squamous sheets, which are eventually shed from the surface ( desquamation ). Differentiated keratinocytes secrete keratin proteins, which contribute to

2205-416: The epidermis is termed epidermal. The epidermis primarily consists of keratinocytes ( proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes , Langerhans cells , Merkel cells , and inflammatory cells. Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae . Blood capillaries are found beneath

2268-456: The epidermis is the main reason for variation in skin color in Homo sapiens . Melanin is found in the small melanosomes , particles formed in melanocytes from where they are transferred to the surrounding keratinocytes. The size, number, and arrangement of the melanosomes vary between racial groups, but while the number of melanocytes can vary between different body regions, their numbers remain

2331-433: The epidermis, and are linked to an arteriole and a venule . The epidermis itself has no blood supply and is nourished almost exclusively by diffused oxygen from the surrounding air. Cellular mechanisms for regulating water and sodium levels ( ENaCs ) are found in all layers of the epidermis. Epidermal cells are tightly interconnected to serve as a tight barrier against the exterior environment. The junctions between

2394-538: The figure is either over- or underestimated. About 1–10% of the global population is estimated to be infected with scabies, but in certain populations, the infection rate may be as high as 50–80%. Scabies has been observed in humans since ancient times. Archeological evidence from Egypt and the Middle East suggests scabies was present as early as 494 BC. In the fourth century BC, Aristotle reported on "lice" that "escape from little pimples if they are pricked" –

2457-436: The fleshworms of the human body". Bonomo's description established scabies as one of the first human diseases with a well-understood cause. In Europe in the late 19th through mid-20th centuries, a sulfur-bearing ointment called by the medical eponym of Wilkinson's ointment was widely used for topical treatment of scabies. The contents and origins of several versions of the ointment were detailed in correspondence published in

2520-402: The formation of an extracellular matrix that is an integral part of the skin barrier function. In normal skin, the rate of keratinocyte production equals the rate of loss, taking about two weeks for a cell to journey from the stratum basale to the top of the stratum granulosum, and an additional four weeks to cross the stratum corneum. The entire epidermis is replaced by new cell growth over

2583-558: The host becomes a more fertile breeding ground for the mites, which spread over the host's body, except the face. The mites in crusted scabies are not more virulent than in noncrusted scabies but are much more numerous, sometimes up to two million. People with crusted scabies exhibit scaly rashes, slight itching, and thick crusts of skin that contain large numbers of scabies mites. For this reason, persons with crusted scabies are more contagious to others than those with typical scabies. Such areas make eradication of mites particularly difficult, as

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2646-523: The host's body to mite proteins, though exactly which proteins remains a topic of study. The mite proteins are also present from the gut, in mite feces, which are deposited under the skin. The allergic reaction is both of the delayed (cell-mediated) and immediate (antibody-mediated) type, and involves IgE (antibodies are presumed to mediate the very rapid symptoms on reinfection). The allergy-type symptoms (itching) continue for some days, and even several weeks, after all mites are killed. New lesions may appear for

2709-484: The inner basal layer or stratum germinativum has formed. This inner layer is a germinal epithelium that gives rise to all epidermal cells. It divides to form the outer spinous layer ( stratum spinosum ). The cells of these two layers, together called the Malpighian layer (s) after Marcello Malpighi , divide to form the superficial granular layer ( Stratum granulosum ) of the epidermis. The cells in

2772-439: The last month and people who live in the same house should also be treated at the same time. Bedding and clothing used in the last three days should be washed in hot water and dried in a hot dryer. As the mite does not live for more than three days away from human skin, more washing is not needed. Symptoms may continue for two to four weeks following treatment. If after this time symptoms continue, retreatment may be needed. Scabies

2835-443: The mite (confirmed scabies), detecting typical lesions in a typical distribution with typical historical features (clinical scabies), or detecting atypical lesions or atypical distribution of lesions with only some historical features present (suspected scabies). Several medications are available to treat those infected, including oral and topical ivermectin , and permethrin , crotamiton , and lindane creams. Sexual contacts within

2898-411: The mites that cause these infestations are of different subspecies from the one typically causing the human form. These subspecies can infest animals that are not their usual hosts, but such infections do not last long. Scabies-infected animals experience severe itching and secondary skin infections. They often lose weight and become frail. The most frequently diagnosed form of scabies in domestic animals

2961-431: The mites. As noted, those re-exposed to scabies after successful treatment may exhibit symptoms of the new infestation in a much shorter period—as little as one to four days. In the classic scenario, the itch is made worse by warmth, and is usually experienced as being worse at night, possibly because distractions are fewer. As a symptom, it is less common in the elderly. The superficial burrows of scabies usually occur in

3024-530: The morning. Care should be taken to coat the entire skin surface, not just symptomatic areas; any patch of skin left untreated can provide a "safe haven" for one or more mites to survive. One application is normally sufficient, as permethrin kills eggs, hatchlings, and adult mites, though many physicians recommend a second application three to seven days later as a precaution. Crusted scabies may require multiple applications, or supplemental treatment with oral ivermectin (below). Permethrin may cause slight irritation of

3087-416: The previous three days should be washed in hot water and dried in a hot dryer. Treatment protocols for crusted scabies are significantly more intense than for common scabies. Permethrin , a pyrethroid insecticide, is the most effective treatment for scabies, and remains the treatment of choice. It is applied from the neck down, usually before sleep, and left on for about 8 to 14 hours, then washed off in

3150-420: The proximity of the neighboring cells and tightness of the junctions, the actin immunofluorescence appears as a border between cells. The epidermis is composed of 4 or 5 layers, depending on the region of skin being considered. Those layers from outermost to innermost are: The epidermis is separated from the dermis, its underlying tissue , by a basement membrane . As a stratified squamous epithelium ,

3213-402: The rise in intracellular calcium concentration. Epidermal organogenesis , the formation of the epidermis, begins in the cells covering the embryo after neurulation , the formation of the central nervous system . In most vertebrates , this original one-layered structure quickly transforms into a two-layered tissue ; a temporary outer layer, the embryonic periderm , which is disposed once

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3276-413: The role of Merkel cells in sensing touch has been thought to be indirect, due their close association with nerve endings. However, recent work in mice and other model organisms demonstrates that Merkel cells intrinsically transform touch into electrical signals that are transmitted to the nervous system. Laboratory culture of keratinocytes to form a 3D structure ( artificial skin ) recapitulating most of

3339-429: The same in individual body regions in all human beings. In white and Asian skin the melanosomes are packed in "aggregates", but in black skin they are larger and distributed more evenly. The number of melanosomes in the keratinocytes increases with UV radiation exposure, while their distribution remain largely unaffected. The skin contains specialized epidermal touch receptor cells called Merkel cells . Historically,

3402-407: The same phylogenetic class ( Arachnida ) as spiders and ticks. S. scabiei mites are under 0.5 mm in size; they are sometimes visible as pinpoints of white. Gravid females tunnel into the dead, outermost layer ( stratum corneum ) of a host's skin and deposit eggs in the shallow burrows. The eggs hatch into larvae in three to ten days. These young mites move about on the skin and molt into

3465-570: The sharing of clothes, towels, and bedding, but this is not a major mode of transmission; individual mites can survive for only two to three days, at most, away from human skin at room temperature. As with lice, a latex condom is ineffective against scabies transmission during intercourse, because mites typically migrate from one individual to the next at sites other than the sex organs. Healthcare workers are at risk of contracting scabies from patients, because they may be in extended contact with them. The symptoms are caused by an allergic reaction of

3528-421: The skin directly. Symptoms of early scabies infestation mirror other skin diseases, including dermatitis , syphilis , erythema multiforme , various urticaria -related syndromes, allergic reactions, ringworm-related diseases, and other ectoparasites such as lice and fleas . Mass-treatment programs that use topical permethrin or oral ivermectin have been effective in reducing the prevalence of scabies in

3591-405: The skin that is usually tolerable. In recent years, concern is growing about permethrin-resistant scabies, although some researchers refer to this as pseudo-resistance. Oral ivermectin is effective in eradicating scabies, often in a single dose. It is the treatment of choice for crusted scabies, and is sometimes prescribed in combination with a topical agent. It has not been tested on infants, and

3654-529: The skin. Scabies is caused by infection with the female mite Sarcoptes scabiei var. hominis , an ectoparasite . The mites burrow into the skin to live and deposit eggs. The symptoms of scabies are due to an allergic reaction to the mites. Often, only between 10 and 15 mites are involved in an infection. Scabies is most often spread during a relatively long period of direct skin contact with an infected person (at least 10 minutes) such as that which may occur during sexual activity or living together. Spread of

3717-490: The skin. In a first-ever infection, the infected person usually develops symptoms within two to six weeks. During a second infection, symptoms may begin within 24 hours. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection in

3780-405: The skin; however, interpreting this test may be difficult, as the burrows are scarce and may be obscured by scratch marks. A definitive diagnosis is made by finding either the scabies mites or their eggs and fecal pellets. Searches for these signs involve either scraping a suspected area, mounting the sample in potassium hydroxide and examining it under a microscope, or using dermoscopy to examine

3843-413: The stratum corneum. The ability of the skin to hold water is primarily due to the stratum corneum and is critical for maintaining healthy skin. Skin hydration is quantified using corneometry . Lipids arranged through a gradient and in an organized manner between the cells of the stratum corneum form a barrier to transepidermal water loss . The amount and distribution of melanin pigment in

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3906-446: The stratum granulosum do not divide, but instead form skin cells called keratinocytes from the granules of keratin . These skin cells finally become the cornified layer ( stratum corneum ), the outermost epidermal layer, where the cells become flattened sacks with their nuclei located at one end of the cell. After birth these outermost cells are replaced by new cells from the stratum granulosum and throughout life they are shed at

3969-438: The trails of the burrowing mites are linear or S-shaped tracks in the skin, often accompanied by rows of small, pimple-like mosquito or insect bites. Lesions are symmetrical, and mainly affect the hands, wrists, axillae, thighs, buttocks, waist, soles of the feet, areola and vulva in females, and penis and scrotum in males. The neck and above are usually not affected, except in cases of crusted scabies and in infestations of infants,

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