Intervention programs in Panama, Brazil, the Solomon Islands, and remote northern Australian Aboriginal communities have resulted in dramatic reductions in the prevalence of scabies and skin sores 58 , , Success at the individual community level has varied and has not always been sustainable. Often low levels of scabies persist within communities after the implementation of these community-based programs Furthermore, mass community treatment in communities of endemicity creates an environment for emerging drug tolerance or resistance, and new approaches to control are needed.
Published in vitro acaricide efficacy studies indicate that S. Resistance should also be considered in regions of nonendemicity when patients experience persistent symptoms for up to several weeks after curative treatment. Promising new acaricides include a number of essential oils in which terpenoids are most likely the primary active components In the treatment of crusted scabies, the importance of combining topical therapy with oral ivermectin has been noted Severe crusted-scabies cases may require up to seven doses of ivermectin to ensure the cure and eradication of mites 64 , Currently there is no efficient means of diagnosing human or animal scabies.
Detecting visible lesions can be difficult, as they are often obscured by eczema or impetigo or are atypical. Detection of burrows with India ink was advocated more than 20 years ago , but the test is often impractical and is not routinely used. Presumptive diagnosis can be made on the basis of a typical history of pruritus, pruritus that is worse at night, the distribution of the inflammatory papules, and a history of contact with other scabies cases Definitive diagnosis is based on the identification of mites, eggs, eggshell fragments, or mite fecal pellets from skin scrapings e.
This method provides excellent specificity but has low sensitivity for ordinary scabies, due to the low numbers of parasites. Furthermore, several factors may influence the level of sensitivity, e. A skin biopsy may confirm the diagnosis of scabies if a mite or parts of it can be identified. However, in most cases, the histological appearance is that of nonspecific, delayed hypersensitivity with superficial and deep perivascular inflammatory mononuclear cell infiltrates with numerous eosinophils, papillary edema, and epidermal spongiosis In practice, identifying a mite is challenging, and a negative result, even from an expert, does not rule out scabies.
Presumptive therapy can be used as a diagnosis, but its value is questionable and confounded by the variable delay until resolution of symptoms following therapy. A positive response to treatment cannot exclude the spontaneous disappearance of a dermatological disease other than scabies, and a negative response does not exclude scabies, especially with resistant mites In the absence of confirmed mites, diagnosis is currently based entirely on clinical and epidemiological findings.
Given the extensive differential diagnoses, the specificity of clinical diagnosis is poor, especially for those inexperienced regarding scabies. Furthermore, there are the difficulties in distinguishing among active infestation, residual skin reaction, and reinfestation.
Problems in Diagnosing Scabies, a Global Disease in Human and Animal Populations
Epiluminescence microscopy and high-resolution videodermatoscopy are noninvasive techniques that allow detailed inspection of the patient's skin, from the surface to the superficial papillary dermis 2 , 49 , Due to difficulties obtaining skin scrapings from some patients, e. The key weakness of a scabies PCR diagnostic is that, as with microscopy diagnosis, it relies on the physical presence of a mite or mite part in the sample. Therefore, it is unlikely to become a viable test for widespread use, due to the generally low mite burden and, thus, low sensitivity.
PCR followed by enzyme-linked immunosorbent assay detection of the PCR product was suggested to be a sensitive technique for diagnosing patients with atypical scabies However, the method described was labor-intensive and time-consuming. The intradermal skin test method is currently not feasible to use with whole-mite extract due to the inability to culture sufficient quantities of S. Furthermore, whole-mite extracts obtained from animal models contain a heterogenous mixture of host and parasite antigens, including house dust mite cross-reactive epitopes, and vary in composition, potency, and purity.
Patients with scabies often present to clinicians with a generalized pruritus of unknown cause. Purified, well-characterized recombinant scabies mite allergens with standardized protein contents could potentially be utilized in the future for scabies skin test assays for clinically difficult-to-diagnose cases and for immunotherapy. Studies document that scabies mite infestation causes the production of measurable antibodies in infested host species 4 , Furthermore, host IgG has been demonstrated in the anterior midgut and esophagus of fresh mites 94 , Enzyme-linked immunosorbent assays have now been developed for the detection of antibodies to S.
These assays rely on whole-mite antigen preparations derived from S. This is not surprising, as studies using molecular markers suggest that S. A major limitation in biomedical research on scabies has been the difficulty of obtaining mites in sufficient numbers, due to the generally low parasite burden and the lack of an in vitro culture system.
To overcome this, cDNA libraries have now been constructed from S. From these databases, scabies mite homologues to most of the known house dust mite allergens have now been identified, as well as many other relevant molecules 33 , 43 , 61 , 62 , 75 , Recombinant antigens promise a continuous, reproducible quantity of allergenic proteins in a purified form suitable for use in in vitro assays.
Recently, a number of scabies mite homologues to house dust mite allergens have been cloned, expressed, and affinity purified. These include mature forms of both active and inactive homologues of the cysteine protease group 1 allergens 62 , mature forms of active and inactive homologues of the serine protease group 3 allergens 61 , a mu class and a delta class glutathione S -transferase group 8 allergen 33 , 91 , and a homologue to the C terminus of an apolipoprotein group 14 allergen Immunohistochemical staining of sections of human skin which was highly infested with S.
Moreover, the group 1 and group 3 scabies mite allergens have now been expressed in Pichia pastoris , with considerable evidence that they are in native conformation and that they are localized to the digestive system of the mite ; D. Studies are now under way to evaluate the diagnostic potential of the identified proteins by characterizing specific human and animal humoral and cellular immune responses. Serological features that are diagnostically important are the interval between exposure to infection and antibody response and the nature of the antibodies that make up the response.
Serial section of human scabies mite. Red shows binding of polyclonal S. Using an appropriate recombinant antigen, the development of an S.
Problems in Diagnosing Scabies, a Global Disease in Human and Animal Populations
Its development will enable the selective treatment of affected individuals and animals, reducing the requirement for mass treatment and the associated costs. This should decrease the potential for escalating mite resistance and provide another means of controlling scabies in highly affected areas. There is little evidence that simple mass treatment is effective in the long term.
Molecular studies aimed at improved diagnosis and better therapeutic options will significantly contribute to reductions in the high prevalence of scabies observed currently in resource-poor communities. National Center for Biotechnology Information , U. Journal List Clin Microbiol Rev v. Currie 1, 2, 3.
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Author information Copyright and License information Disclaimer. Menzies School of Health Research, P. Box , Casuarina NT , Australia. This article has been cited by other articles in PMC. Abstract Scabies is a worldwide disease and a major public health problem in many developing countries, related primarily to poverty and overcrowding. Life Cycle The female mite burrows just under the surface of the skin and lays two to three eggs per day in the stratum corneum for up to 6 weeks at a time, resulting in raised papules on the skin's surface.
Open in a separate window. Infectivity, Survival, and Transmission Scabies transmission is mediated primarily by close, prolonged personal contact with an infected person and therefore is common among family members and often seen in institutional settings. Cyclical Pattern of Infection Early accounts of the epidemiology of human scabies described large epidemics or pandemics of scabies.
Poverty, Overcrowding, and Poor Hygiene The relationship between the prevalence of scabies and the relative levels of poverty, crowding, and hygiene within a community is complex. Significance in Australian Indigenous Communities Despite the availability of effective chemotherapy, scabies is still a major problem in many remote Aboriginal communities in Australia, relating primarily to levels of poverty and overcrowding Reinfestation With reinfestation, sensitization develops rapidly, and the associated lesions and pruritus are evident within 24 to 48 h.
Differential Diagnosis The clinical signs and symptoms of scabies infestations can mimic many other skin conditions. Secondary Infection Untreated scabies is often associated with pyoderma from secondary infection with group A streptococcus and S. Crusted Scabies Crusted scabies was first described among leprosy patients in Norway in and thus is historically known as Norwegian scabies. Crusted scabies with chronic secondary ulcers and depigmentation. Clinical Features of Mange The clinical signs of mange in animals are slightly raised red papules seen on the sparsely haired regions of the body.
Host Specificity Mite populations are primarily host specific, with little evidence of interbreeding between strains. Immediate versus Delayed-Type Hypersensitivity Reactions to Scabies Mites The severe itching and papular rash of the primary infestation are accompanied by skin lesions characterized by inflammatory cell infiltrates typical of a delayed sensitivity cell-mediated immune reaction.
Cross-Reactivity between Scabies Mite Infections and House Dust Mite Allergy Investigations have demonstrated that patients sensitive to house dust mites but with no history of scabies have circulating IgE antibodies that recognize antigens in S. TREATMENT There are a number of agents available on the market to treat scabies, and choice is largely based on the age of the patient, state of their health, degree of excoriation or eczema, potential toxicity, cost, and availability.
Microscopy Definitive diagnosis is based on the identification of mites, eggs, eggshell fragments, or mite fecal pellets from skin scrapings e. Dermatoscopy Epiluminescence microscopy and high-resolution videodermatoscopy are noninvasive techniques that allow detailed inspection of the patient's skin, from the surface to the superficial papillary dermis 2 , 49 , Antigen Detection and PCR Diagnostic The key weakness of a scabies PCR diagnostic is that, as with microscopy diagnosis, it relies on the physical presence of a mite or mite part in the sample. Intradermal Skin Test for Scabies The intradermal skin test method is currently not feasible to use with whole-mite extract due to the inability to culture sufficient quantities of S.
Antibody Detection Studies document that scabies mite infestation causes the production of measurable antibodies in infested host species 4 , Immunodiagnostic Assay Using Recombinant S. Arthropods and human skin. Energetic relationships of Sarcoptes scabiei var. Sarcoptidae with the laboratory rabbit. Circulating IgE in patients with ordinary and crusted scabies.
Extracts of scabies mites Sarcoptidae: Sarcoptes scabiei modulate cytokine expression by human peripheral blood mononuclear cells and dendritic cells. Modulation of cytokine expression in human keratinocytes and fibroblasts by extracts of scabies mites. Evidence that scabies mites Acari: Sarcoptidae influence production of interleukin and the function of T-regulatory cells Tr1 in humans. The development of protective immunity in canine scabies. Survival and infestivity of Sarcoptes scabiei var.
Cross infestivity of Sarcoptes scabiei. Host-seeking behavior of Sarcoptes scabiei.
Life cycle of Sarcoptes scabiei var canis. Cross-antigenicity between the scabies mite, Sarcoptes scabiei , and the house dust mite, Dermatophagoides pteronyssinus. Sarcoptic mange Sarcoptes scabiei var. Animal scabies affecting man. Evaluation of an enzyme-linked immunosorbant assay ELISA for the serological diagnosis of canine sarcoptic mange. Serodiagnosis of sarcoptic mange in pigs.
Microbiology of secondary bacterial infection in scabies lesions. Sarcoptes scabiei and scabies. The immunology of scabies. Success of a scabies control program in an Australian aboriginal community. Using slaughter inspections to evaluate sarcoptic mange infestation of finishing swine. Scabies in spinal injuries ward.
Skin infections and infestations in Aboriginal communities in northern Australia. Advertising revenue supports our not-for-profit mission.
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This content does not have an English version. This content does not have an Arabic version. Scabies Scabies is caused by tiny mites that burrow into your skin. Request an Appointment at Mayo Clinic. Mayo Foundation for Medical Education and Research; Goldstein BG, et al. Epidemiology, clinical features, and diagnosis. Accessed May 30, Puza CJ, et al.
Scabies and pruritus — A historical review. Bope ET, et al. Parasitic diseases of the skin. Conn's Current Therapy Accessed June 8, Bennett JE, et al. Mayo Clinic Marketplace Check out these best-sellers and special offers on books and newsletters from Mayo Clinic. Scabies mites leave small red blotches and silver-coloured lines on the skin. These marks are caused by the mites burrowing into the skin. Male mites move between different burrow sites looking to mate.
After hatching, the young mites move to the surface of the skin, where they mature into adults after 10 to 15 days. The life cycle is then repeated. Without effective treatment, the life cycle of the scabies mite can continue indefinitely. Scabies mites are resistant to soap and hot water and can't be scrubbed out of the skin.
It's unlikely that scabies will be transmitted through brief physical contact, such as shaking hands or hugging. There's an increased risk of catching scabies in confined environments, such as schools and nursing homes, where people are in close proximity to one another. Your GP should be able to diagnose scabies from the appearance of your skin, and by looking for the burrow marks of the Sarcoptes scabiei mite.
Your GP will also want to rule out other skin conditions that may be causing your symptoms, such as eczema or impetigo a highly contagious bacterial skin infection. The burrows of scabies mites can be identified by using an ink test. Ink is rubbed around an area of itchy skin before being wiped off with an alcohol pad.
If scabies burrows are present, some of the ink will remain and will have tracked into the burrows, showing up as a dark line. Visit your GP if you think you have scabies. If you think you have genital scabies or your partner has been diagnosed with it, visit your nearest sexual health clinic , where you'll be examined and, if necessary, treated. If you've had genital scabies in the past, anyone you've had sex with in the previous 48 hours will need to be treated. If you're embarrassed about contacting previous sexual partners, your GP surgery or local sexual health clinic may be able to inform them that they've been exposed to scabies on your behalf without disclosing your identity.
Some sexual health clinics operate on a walk-in basis. It's therefore a good idea to call first. When you attend a clinic, you'll be asked for your name, date of birth and contact details. These details will be treated confidentially and won't be passed on to your GP without your agreement. See your GP immediately if you have scabies and you haven't had a previous infection.
Delaying treatment places other people at risk.
As other more serious skin conditions can sometimes cause similar symptoms to the symptoms of scabies , your GP will need to rule these out. If you have scabies, your partner will also need to be treated regardless of whether or not they have any symptoms. Lotions and creams are commonly used to treat scabies. Your GP, pharmacist or nurse will be able to advise you about which treatment to use. Don't apply it after having a hot bath. If you apply it when your body is hot, it will quickly be absorbed into your skin and won't remain on the area where the scabies burrows are.
It can take a month after treatment for the general itching to subside completely, and longer for the lumpy genital lesions to resolve. As this type of antihistamine can cause drowsiness, you should avoid driving or operating heavy machinery if you're affected in this way. Non-sedating antihistamines don't help relieve the itching of scabies.