Scabies , also known as the seven-year itch , is a contagious skin infestation by the mite Sarcoptes scabiei. Scabies is caused by infection with the female mite Sarcoptes scabiei var.
A number of medications are available to treat those infected, including permethrin , crotamiton , and lindane creams and ivermectin pills. Scabies is one of the three most common skin disorders in children, along with ringworm and bacterial skin infections. The characteristic symptoms of a scabies infection include intense itching and superficial burrows.
Similarly, symptoms often persist for one to several weeks after successful eradication of 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.
The superficial burrows of scabies usually occur in the area of the finger webs, feet, ventral wrists, elbows, back, buttocks, and external genitals. The burrows are created by excavation of the adult mite in the epidermis. In most people, 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.
These signs are often found in crevices of the body, such as on the webs of fingers and toes, around the genital area, in stomach folds of the skin, and under the breasts of women.
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 an impaired immune system , such as HIV , cancer , or those on immunosuppressive medications , are susceptible to crusted scabies also called Norwegian scabies.
The mites in crusted scabies are not more virulent than in noncrusted scabies; however, they are much more numerous up to two million. People with crusted scabies exhibit scaly rashes, slight itching, and thick crusts of skin that contain the large numbers of scabies mites.
Due to being infected thus, persons with crusted scabies are more contagious to other persons. In the 18th century, Italian biologists Giovanni Cosimo Bonomo and Diacinto Cestoni — 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 the same phylogenetic class Arachnida as spiders and ticks.
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 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 noncrusted 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 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.
Sarcoptic scabiei morphology pdf writer
Immediate antibody-mediated allergic reactions wheals have been elicited in infected persons, but not in healthy persons; immediate hypersensitivity of this type is thought to explain the observed far more rapid allergic skin response to reinfection seen in persons having been previously infected especially having been infected within the previous year or two. Scabies is contagious and can be contracted through prolonged physical contact with an infested person.
Less commonly, scabies infestation can happen through 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. 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 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.
New lesions may appear for 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 is present in another household member. 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 the skin; however, interpreting this test may be difficult, as the burrows are scarce and may be obscured by scratch marks. 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 a number of populations.
The simultaneous treatment of all close contacts is recommended, even if they show no symptoms of infection asymptomatic , to reduce rates of recurrence. Therefore cleaning is of little importance. A number of 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.
Permethrin , a pyrethroid insecticide, is the most effective treatment for scabies,  and remains the treatment of choice.
One application is normally sufficient, as permethrin kills eggs and hatchlings, as well as 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. Oral ivermectin is effective in eradicating scabies, often in a single dose. Topical ivermectin preparations have been shown to be effective for scabies in adults, though only one such formulation is available in the United States at present, and it is not FDA-approved as a scabies treatment. Other treatments include lindane, benzyl benzoate , crotamiton , malathion , and sulfur preparations.
Scabies 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.
SCABIES, Causes, Signs and Symptoms, Diagnosis and Treatment.
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 is one of the three most common skin disorders in children, along with tinea and pyoderma. Scabies has been observed in humans since ancient times. The Roman encyclopedist and medical writer Aulus Cornelius Celsus c. In Europe in the late 19th through midth 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 the British Medical Journal in The International Alliance for the Control of Scabies was started in ,    and brings together over researchers, clinicians, and public-health experts from more than 15 different countries.
It has managed to bring the global health implications of scabies to the attention of the World Health Organization. Scabies may occur in a number of domestic and wild animals; the mites that cause these infestations are of different subspecies from the one typically causing the human form. They often lose weight and become frail.
The most frequently diagnosed form of scabies in domestic animals 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 suffer what is known as "scaly leg".
Domestic animals that have gone feral and have no veterinary care are frequently afflicted with scabies and a host of other ailments. Gorillas, for instance, are known to be susceptible to infection by contact with items used by humans. Moxidectin is being evaluated as a treatment for scabies. Its advantage over ivermectin is its longer half life in humans and, thus, potential duration of action.
From Wikipedia, the free encyclopedia. Human disease. For psychological condition, see The seven-year itch. Main article: Sarcoptes scabiei. Play media. Main articles: Sarcoptic mange and Acariasis. Infectious disease secrets 2. Philadelphia: Elsevier, Hanley Belfus.
Center for Disease Control and Prevention. November 2, Archived from the original on 2 May Retrieved 18 May Centers for Disease Control and Prevention.
Archived from the original on 29 April World Health Organization. Archived from the original on Retrieved Archived from the original on 18 May Archived from the original on 30 April Deutsches Arzteblatt International. Archived from the original on 28 April North Am. Mosby-Year Book Inc.