162 CDI Vol 35 No 2 2011 Peer-reviewed articles Peer-reviewed articles NOROVIRUS IN RESIDENTIAL CARE FACILITIES: DOES PROMPT NOTIFICATION OF OUTBREAKS HELP? Craig A Davis, Hassan Vally, Frank H Beard Abstract Outbreaks of viral gastroenteritis occur regularly in residential care facilities (RCFs), with norovirus being the most common agent. Notification of out- breaks to public health authorities is encouraged in Australia, although there is limited evidence that this results in public health benefit. The aim of this study was to investigate if prompt notification of suspected norovirus outbreaks to public health authorities is associated with a reduction in either the duration or attack rate of outbreaks. Viral gas- troenteritis outbreaks notified from Queensland RCFs between 2004 and 2007 were analysed. Foodborne outbreaks were excluded, along with 6 outbreaks where viruses other than norovirus were identified as the causative agent. Of the 264 remaining outbreaks, 70.8% were laboratory- confirmed as being due to norovirus. The average time to notification was 4 days and the average duration of outbreaks was 12 days. Outbreaks notified promptly (within 1 day) were of significantly shorter duration compared with outbreaks notified within 2–3 days ( P < 0.02) or 4 or more days ( P < 0.001). Early notification of outbreaks was not significantly associated with a reduced attack rate, however there was a significantly higher attack rate in facilities with less than 150 individuals at risk compared with facilities with 150 or more individuals at risk (30% versus 18%, respectively; P < 0.001). The shorter duration of promptly noti- fied outbreaks provides some evidence to support recommendations from best practice guidelines for prompt notification of outbreaks by RCFs. However, further research is needed to unravel the interplay of factors that may influence the severity of viral gastroenteritis outbreaks in RCFs. Commun Dis Intell 2011;35(2):162–167. Keywords: norovirus, viral gastroenteritis, residential care facilities, outbreak management, and notification of outbreaks Introduction Viral gastroenteritis affects all age groups, with par- ticularly severe disease occurring in the elderly and people with chronic diseases. 1 Outbreaks of viral gastroenteritis are commonly reported from resi- dential care facilities (RCFs) 2–4 where they may be long-lasting and may result in deaths. 1,5 A number of viruses may cause these outbreaks, including norovirus, rotaviruses, and adenoviruses, 6 although norovirus is by far the most common. 1,4,5 Norovirus is most commonly associated with outbreaks because it requires only a small infective dose, 5,7–9 may be transmitted via multiple routes (i.e. person-to-person, food, water and environ- mental sources), 1,9,10 may become established well before the outbreak is identified, 8 immunity is usually short-lived, 9,11,12 is highly stable in the environment, 13,14 and is resistant to disinfectants. 9 Outbreaks in RCFs are also facilitated by factors such as decreased personal hygiene related to immobility, incontinence and dementia. 2,15 Host susceptibility is considered general although vari- able, 9 and transmission, particularly within out- break settings, may be enhanced by extended peri- ods of symptoms and viral shedding 1,9,14,16 as well as asymptomatic infection. 14,17 Aerosolisation of viral particles may occur during vomiting 18 and environ- mental surface contamination is a significant factor contributing to transmission in the enclosed living conditions of institutional facilities. 9,15,19 Outbreaks cause considerable additional workload and logistical and economic burden for institutional facilities and public health authorities. 20–24 In resi- dential care facilities ill residents require isolation and additional care, and in more serious cases may require hospitalisation. Common areas may be closed to residents and sometimes entire wings or facilities may be closed to visitors. Additional clean- ing and infection control measures are required and there are staff productivity costs. For public health authorities, outbreaks trigger a range of investiga- tions (laboratory, environmental and epidemiologi- cal), as well as additional surveillance and reporting requirements. 5,25 A range of public health guidelines in Australia 26–28 advise on how to manage gastroenteritis outbreaks in RCFs, including the management of ill patients, staff and visitors, cleaning and disinfection, and monitoring and investigation. These guidelines encourage notification of outbreaks to public health, although there is little evidence that early identifica- tion and intervention are an effective use of public health resources.