Scabies
Scabies | |
---|---|
Other names | Seven-year itch |
Medication | permethrin, crotamiton, lindane, ivermectin[8] |
Frequency | 204 million / 2.8% (2015)[9] |
Scabies (
Scabies is caused by infection with the female
Several medications are available to treat those infected, including oral and topical ivermectin, and permethrin, crotamiton, and lindane creams.[8] Sexual contacts within the last month and people who live in the same house should also be treated at the same time.[13] Bedding and clothing used in the last three days should be washed in hot water and dried in a hot dryer.[13] As the mite does not live for more than three days away from human skin, more washing is not needed.[13] Symptoms may continue for two to four weeks following treatment.[13] If after this time symptoms continue, retreatment may be needed.[13]
Scabies is one of the three most common skin disorders in children, along with
Other animals do not spread human scabies;
Signs and symptoms
The characteristic symptoms of a scabies infection include intense
Itching
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.[19] As a symptom, it is less common in the elderly.[19]
Rash
The superficial burrows of scabies usually occur in the area of the finger webs, feet, ventral wrists, elbows, back, buttocks, and external genitals.
-
Scabies of the foot
-
Scabies of the arm
-
Scabies of the hand
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. 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, the elderly, and the immunocompromised.[21] 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.[22]
Crusted scabies
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).[19][22][23] On those with weaker immune systems, 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.[3][24] Such areas make eradication of mites particularly difficult, as the crusts protect the mites from topical miticides/scabicides, necessitating prolonged treatment of these areas.[citation needed]
Cause
Scabies mite
In the 18th century, Italian biologists
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 (
The movement of mites within and on the skin produces an intense itch, which has the characteristics of a delayed
Transmission
Scabies is
Healthcare workers are at risk of contracting scabies from patients, because they may be in extended contact with them.[31]
Pathophysiology
The symptoms are caused by an
Rates of scabies are negatively related to temperature and positively related to humidity.[32]
Diagnosis
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.
Differential diagnosis
Symptoms of early scabies infestation mirror other skin diseases, including
Prevention of passing on scabies to other people
Mass-treatment programs that use topical permethrin or oral ivermectin have been effective in reducing the prevalence of scabies in a number of populations.[15] 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.[15] 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 is of little importance.[15] Rooms used by those with crusted scabies require thorough cleaning.[34]
Management
Treatment
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.[15] In addition to treating the infestation, options to control itchiness include antihistamines and prescription anti-inflammatory agents.[35] Bedding, clothing and towels used during the previous three days should be washed in hot water and dried in a hot dryer.[36]
Treatment protocols for crusted scabies are significantly more intense than for common scabies.[8][37][38]
Permethrin
Permethrin, a pyrethroid insecticide, is the most effective treatment for scabies,[39] and remains the treatment of choice.[15][40] It is applied from the neck down, usually before sleep, and left on for about eight to 14 hours, then washed off in the morning.[15] 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 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).[15][40][41] Permethrin may cause slight irritation of the skin that is usually tolerable.[19]
Ivermectin
Oral ivermectin is effective in eradicating scabies, often in a single dose.[4][15] It is the treatment of choice for crusted scabies, and is sometimes prescribed in combination with a topical agent.[15][19] It has not been tested on infants, and is not recommended for children under six years of age.[19]
One review found that the efficacy of permethrin is similar to that of systemic or topical ivermectin.[45] A separate review found that although oral ivermectin is usually effective for treatment of scabies, it does have a higher treatment failure rate than topical permethrin.[46] Another review found that oral ivermectin provided a reasonable balance between efficacy and safety.[47] A study has demonstrated that scabies is markedly reduced in populations taking ivermectin regularly;[48] the drug is widely used for treating scabies and other parasitic diseases particularly among the poor and disadvantaged in the tropics, beginning with the developer Merck providing the drug at no cost to treat onchocerciasis from 1987.[49]
Others
Other treatments include lindane, benzyl benzoate, crotamiton, malathion, and sulfur preparations.[15][19] Lindane is effective, but concerns over potential neurotoxicity have limited its availability in many countries.[19] It is banned in California,[50] but may be used in other states as a second-line treatment.[51] Sulfur ointments or benzyl benzoate are often used in the developing world due to their low cost;[19] Some 10% sulfur solutions have been shown to be effective,[52] and sulfur ointments are typically used for at least a week, though many people find the odor of sulfur products unpleasant.[19] Crotamiton has been found to be less effective than permethrin in limited studies.[19] Crotamiton or sulfur preparations are sometimes recommended instead of permethrin for children, due to concerns over dermal absorption of permethrin.[15]
-
Day 4
-
Day 8 (treatment begins)
-
Day 12 (under treatment)
-
Healed
Communities
Scabies is endemic in many developing countries,[15] 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.[53] Although such strategies have shown to be able to reduce the burden of scabies in these kinds of communities, debate remains about the best strategy to adopt, including the choice of drug.[53][54]
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.[53][54]
Epidemiology
Scabies is one of the three most common skin disorders in children, along with
History
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.[20][57] In the fourth century BC, Aristotle reported on "lice" that "escape from little pimples if they are pricked" – a description consistent with scabies.[58] Arab physician Ibn Zuhr is believed to have been the first to provide a clinical description of the scabies mites.[59]
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.[58] The parasitic etiology of scabies was documented by Italian physician Giovanni Cosimo Bonomo (1663–1696) in his 1687 letter, "Observations concerning the fleshworms of the human body".[58] Bonomo's description established scabies as one of the first human diseases with a well-understood cause.[20][57]
In Europe in the late 19th through mid-20th centuries, a sulfur-bearing
Scabies in animals
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.[19] These subspecies can infest animals that are not their usual hosts, but such infections do not last long.[19] Scabies-infected animals experience severe itching and secondary skin infections. They often lose weight and become frail.[26]
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,[61] 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 and a host of other ailments.[62] 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,[63] and it is a fatal disease of wombats.[64]
Scabies is also a concern for cattle.[65][66][67][68]
Society and culture
The International Alliance for the Control of Scabies was started in 2012,[6][54][69] 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).[54] Consequently, the WHO has included scabies on its official list of neglected tropical diseases and other neglected conditions.[70]
Research
Moxidectin is being evaluated as a treatment for scabies.[71] 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.[72]
Tea tree oil (TTO) exhibits scabicidal action in a laboratory setting.[73]
References
- ^ ISBN 978-1-56053-543-0.
- ^ a b c d e f g h i j k l "Parasites – Scabies Disease". Center for Disease Control and Prevention. 2 November 2010. Archived from the original on 2 May 2015. Retrieved 18 May 2015.
- ^ a b c d e f g h i j k l "Parasites - Scabies: Epidemiology & Risk Factors". Centers for Disease Control and Prevention. 2 November 2010. Archived from the original on 29 April 2015. Retrieved 1 January 2024.
- ^ a b c "WHO -Water-related Disease". World Health Organization. Archived from the original on 22 October 2010. Retrieved 10 October 2010.
- ^ Muthiani Y (21 June 2017). "Potential skin pathogens on second hand clothes and the effectiveness of disinfection methods". JKUAT Annual Scientific Conference.
- ^ a b c d "Scabies". World Health Organization. Archived from the original on 18 May 2015. Retrieved 18 May 2015.
- ISBN 978-0323076999.
- ^ a b c "Parasites – Scabies Medications". Center for Disease Control and Prevention. 2 October 2019. Archived from the original on 30 April 2015.
- ^ PMID 27733282.
- ISBN 978-1-4058-8118-0.
- ISBN 9780801672255.
- PMID 27974144.
- ^ a b c d e f "Parasites - Scabies Treatment". Center for Disease Control and Prevention. 2 November 2010. Archived from the original on 28 April 2015. Retrieved 18 May 2015.
- PMID 32034956.
- ^ PMID 19962029.
- ^ PMID 23245607.
- ISBN 9781455739882.
- ^ a b "Scabies". CDC Parasitology Diagnostic Web Site. Archived from the original on 20 February 2009. Retrieved 9 February 2009.
- ^ S2CID 41376428.
- ^ ISBN 978-0-7216-4793-7.
- ^ a b Maguire JR (March 2022). "Scabies: Diagnosis and Treatment with Images". DermNet. With link to many images
- ^ S2CID 206001293.
- S2CID 221647574.
- ^ a b "DPDx – Scabies". Laboratory Identification of Parasites of Public Health Concern. CDC. Archived from the original on 20 February 2009.
- ISSN 0044-586X.
- ^ PMID 17428886.
- ISBN 978-0-8160-6403-8.
- ^ "Scabies Causes". WebMD. October 2010. Archived from the original on 22 September 2010. Retrieved 9 October 2010.
- PMID 16625010.
- ^ "Scabies – Fast Facts". American Social Health Association. Archived from the original on 22 April 2011. Retrieved 9 October 2010.
- PMID 24566946.
- PMID 27905271.
- PMID 2494934.
- ^ "Prevention and Control – Scabies". Center for Disease Control and Prevention. Archived from the original on 7 March 2010. Retrieved 9 October 2010.
- S2CID 72142958.
- ^ "Parasites - Scabies". cdc.gov. 2 November 2010. Archived from the original on 11 December 2014. Retrieved 11 December 2014.
- S2CID 32956377.
- ^ Thomas L (October 2021). "Crusted scabies". DermNet.
- PMID 17636630.
- ^ a b "Scabies". Illinois Department of Public Health. January 2008. Archived from the original on 5 December 2010. Retrieved 7 October 2010.
- ISBN 978-0-553-59340-2.
- S2CID 39384922.
- S2CID 28579947.
- PMID 26981951.
- PMID 29608022.
- PMID 29241784.
- PMID 30654070.
- PMID 21321478.
- PMID 28285851.
- PMID 18335094.
- ^ "FDA Public Health Advisory: Safety of Topical Lindane Products for the Treatment of Scabies and Lice". Fda.gov. 30 April 2009. Archived from the original on 26 November 2010. Retrieved 14 November 2010.
- S2CID 21544520.
- ^ S2CID 26416151.
- ^ PMID 23951369.
- PMID 2509232.
- S2CID 221647574.
- ^ a b "Scabies homepage". Stanford University. Archived from the original on 13 May 2010. Retrieved 9 October 2010.
- ^ PMID 3307123.
- ^ "Ibn Zuhr | Encyclopedia.com". www.encyclopedia.com.
- PMC 2056959.
- ^ Borgman W (June 30, 2006). Dog mange called scabies can transfer to humans. Orlando Sentinel archive Archived 2015-02-16 at the Wayback Machine. Retrieved February 16, 2015.
- ^ "Bali Animal Welfare Association". Archived from the original on 26 February 2010. Retrieved 28 July 2009.
- ^ "Uganda: Out of the Wild". Frontline. PBS. Archived from the original on 5 November 2013. Transcript | A Death In Tehran | FRONTLINE | PBS (section on rare diseases in Uganda). Retrieved 4 November 2013.
- ^ Old JM, Sengupta C, Narayan E, Wolfenden J (2018). Sarcoptic mange in wombats – A review and future research directions. Transboundary and Emerging Diseases. 65, 399-407. DOI: 10.1111/tbed.12770
- ^ Reichard MV (15 May 2015). "Mange in Cattle - Integumentary System". Merck Veterinary Manual. Retrieved 22 April 2022.
- Texas A & M UniversityExtension Beef Cattle Resource Committee. pp. 1–3.
- US Department of Agriculture. p. 591.: 292–297
- ^ "Beef cattle-Scabies mite". Pacific Northwest Pest Management Handbooks. Pacific Northwest Extension (Oregon, Washington, Idaho). 22 October 2015. Retrieved 22 April 2022.
- ^ "International Alliance for the Control of Scabies". International Alliance for the Control of Scabies. Archived from the original on 2 February 2014. Retrieved 1 February 2014.
- ^ "The 17 neglected tropical diseases". Neglected tropical diseases. World Health Organization. Archived from the original on 22 February 2014. Retrieved 1 February 2014.
- PMID 26985995.
- PMID 24533275.
- PMID 26787146.
Bibliography
- Friedman R (1947). The Story of Scabies. Froben Press. ASIN B0007FK79C.
- Craig E (2022). The Itch : Scabies. Oxford University Press. ISBN 978-0192848406.