A 2009 varicella outbreak in a Connecticut residential facility for adults with intellectual disability.

We investigated a varicella outbreak in a residential facility for adults with intellectual disabilities. A case of varicella was defined as a generalized maculopapular rash that developed in a facility resident or employee. Immunoglobulin M testing was conducted on serologic samples, and polymerase chain reaction testing was performed on environmental and skin lesion samples. Eleven cases were identified among 70 residents and 2 among ∼145 staff. An unrecognized case of herpes zoster was the likely source. Case patients first entered any residential facility at a younger age than non-case residents (9.5 vs 15.0 years; P < .01). Varicella zoster virus DNA was detected 2 months after the outbreak in environmental samples obtained from case patients' residences. This outbreak exemplifies the potential for at-risk pockets of varicella-susceptible adults, especially among those who have lived in residential facilities from a young age. Evidence of immunity should be verified for all adults and healthcare staff in similar residential settings.