How can we learn more about scabies worldwide?

Scabies is very common throughout the world. It is caused by a parasitic mite, Sarcoptes scabiei var. hominis , which burrows into the skin and causes intense itching. It is spread by skin‐to‐skin contact. Children are especially affected. Severe itching can lead to sleep deprivation, impaired concentration, time off school or work, and economic hardship. In low income areas of the world, secondary bacterial infection with Staphylococcus aureus and Streptococcus pyogenes is common. This leads to boils and abscesses, and streptococcal infection can even lead to kidney failure and heart valve disease. The authors, based in the UK and Australia, reviewed what is known about the prevalence of scabies, how it is spread, and approaches to disease control. In 2012, the International Alliance for Control of Scabies (IACS) was established, with the aim of identifying priorities and supporting research into diagnosis and treatment. Scabies is generally diagnosed by healthcare practitioners in their clinics. Sometimes, but not always, the diagnosis can be confirmed by examining skin scrapings under the microscope, but this is time‐consuming and taking skin samples can be distressing for children. Examination with a hand‐held magnifier called a dermatoscope may be helpful, but dermatoscopes are expensive and not freely available in resource‐poor areas. Other diagnostic aids being developed include low‐cost means of magnification and a testing method called rapid antigen detection. Diagnosis can often be delayed because of a lack of clear diagnostic standards, meaning defined standards which will help healthcare workers evaluate if the symptoms are scabies. Researchers in several countries have devised algorithms to aid diagnosis by primary care health workers, but these have proved of limited value. IACS has led a discussion to improve diagnostic criteria, released in 2020. The global prevalence of scabies – meaning how many people have it – was estimated at 175 406 000 in 2017, but this may be an underestimate; however, little is known about its relative prevalence within vulnerable communities compared with more affluent populations in the same country. It is reported to be commoner in disadvantaged communities, for example among refugees. Severe systemic illness (meaning it affects other organs in the body) caused by streptococcal infection is common (estimated at around 18 million people) in resource‐poor areas, but it is not clear how much is secondary to scabies. The World Health Organization has classified scabies as a neglected ttropical disease (NTD). Integration of epidemiology (which looks at things like patterns, causes and risk factors) and treatment programmes for scabies with other skin NTDs is proving successful in several parts of the world. This strengthens the case for increased funding of control programmes. Linked Article:   Cox et al . Br J Dermatol 2021; 184 :237–242.