A prospective study of scabies outbreaks in ten residential care facilities for the elderly in South-East England, 2014-15

Introduction Scabies is a significant problem in UK elderly residential care facilities (RCF); outbreaks are common and difficult to control. Clinical presentations in the elderly are poorly understood. We studied scabies outbreaks in RCFs to investigate the clinical signs and risk factors in this population. Methods We visited RCFs with suspected scabies outbreaks. We examined residents, performed dermoscopy and skin scrapings, and classified their scabies diagnosis as definite (mite visualised)/probable (compatible symptoms, mite not visualised)/possible (non-specific rash + contact with case) or non-scabies. All residents were treated twice with a topical scabicide, and a second visit conducted. Results We examined 230 residents at 10 RCFs between 03/02/2014-11/02/2015. Their median age was 87 years, 76% were female, and 68% had dementia. 61 (27%) had scabies (13% definite); 41% with burrows, 51% had not reported symptoms. Dermoscopy identified the mite in 7 cases (11.5%), skin scrapings in 3. We diagnosed a median 6 cases/RCF. Dementia was strongly associated with scabies (OR=2.4, 95% CI 1.4-4.1). No new cases were identified at the second visit (median interval 44 days), 10 cases still had scabies (2 probable, 8 possible). Discussion Scabies diagnosis is difficult in this population; half of cases were asymptomatic, and dermoscopy and skin scrapings were of limited diagnostic value. Our study is the first to confirm that dementia is a risk factor for scabies in this group. Careful examination of elderly residents of RCFs with suspected scabies outbreaks is important, particularly those with dementia, as they may have no obvious clinical signs.