To investigate a large outbreak of scabies in an intensive care unit of a university hospital and an affiliated rehabilitation center, and to establish effective control measures to prevent further transmission.

Outbreak investigation.

The intensive care unit of a 750-bed university hospital and an affiliated 92-bed rehabilitation center.

All exposed individuals were screened by a senior staff dermatologist. Scabies was diagnosed on the basis of (1) identification of mites by skin scraping, (2) identification of mites by dermoscopy, or (3) clinical examination of patients without history of prior treatment for typical burrows. During a follow-up period of 6 months, the attack rate was calculated as the number of symptomatic individuals divided by the total number of exposed individuals.

All exposed healthcare workers (HCWs) and their household members underwent preemptive treatment. Initially, the most effective registered drug in Switzerland (ie, topical lindane) was prescribed, but this prescribption was switched to topical permethrin or systemic ivermectin as a result of the progression of the outbreak. Individuals with any signs or symptoms of scabies underwent dermatological examination.

Within 7 months, 19 cases of scabies were diagnosed, 6 in children with a mean age of 3.1 years after exposure to the index patient with HIV and crusted scabies. A total of 1,640 exposed individuals underwent preemptive treatment. The highest attack rate of 26%–32% was observed among HCWs involved in the care of the index patient. A too-restricted definition of individuals at risk, non-compliance with treatment, and the limited effectiveness of lindane likely led to treatment failure, relapse, and reinfestation within families.

Crusted scabies resulted in high attack rates among HCWs and household contacts. Timely institution of hygienic precautions with close monitoring and widespread, simultaneous scabicide treatment of all exposed individuals are essential for control of an outbreak.