Prevention and Control of Norovirus Outbreaks in Long-Term Care Facilities: The California Experience, 2002-2007

      ISSUE: Norovirus outbreaks are common, occur seasonally, and disproportionately affect long-term care facilities (LTCF), particularly skilled nursing facilities (SNF), where the transmission is almost always person-to-person. In 2002 the California Department of Health Services recognized that the etiology and nature of transmission of such outbreaks were often not recognized, and therefore poorly reported, investigated or controlled.
      PROJECT: A series of interventions were implemented to improve the control of norovirus outbreaks in California LTCF. A guideline for the control of outbreaks of acute gastroenteritis was developed and distributed to all licensed healthcare facilities, local health departments (LHD), and licensing and certification (L&C) offices in December 2002 and annually thereafter. Sample line listings for ill residents and staff and a sample summary log were included, and facilities encouraged or, in some cases, required by LHD or L&C to be reported. A guideline for the investigation of norovirus outbreaks was developed and distributed to LHD and L&C offices in December 2003. Because of ongoing questions from LHD, a control checklist and supplemental guidelines in the form of questions and answers were distributed in December 2006 and January 2007. Where line listings were available, epidemiologic curves were generated and examined for efficacy of control interventions.
      RESULTS: The initial publication of the guideline was followed by an immediate increase in reports of outbreaks to local health departments and L&C offices. In 2007, in response to an apparent increase in outbreaks compared to previous years, issues not anticipated in the guidelines arose from LHD and were addressed in supplemental guidelines. Issues included closure of the facility to new admissions and/or visitors, restriction of workers from working at other facilities, the duration of exclusion of ill employees, restriction of asymptomatic residents to their rooms (quarantine), use of alcohol hand hygiene products, and methods of cleaning and disinfection including the use of disinfectants registered by the Environmental Protection Agency (EPA) as effective against norovirus. Some epidemiologic curves showed rapid diminutions in daily case counts, possibly in association with implementation of recommended control measures, while others continued for weeks until resident attack rates of reached 50-70%. Control appeared to be unlikely when four or more of residents became ill on a single day, often anecdotally associated with residents or staff vomiting in a location that exposed multiple persons and/or contaminated frequently touched and difficult to clean environmental surfaces.
      LESSONS LEARNED: Outbreaks of norovirus are common in LTCF, occur seasonally, and are transmitted person-to-person propagated by direct exposure to vomitus and contact with ill persons and contaminated environmental surfaces. The key to containment is early recognition and implementation of control measures. Specific studies to determine best methods to achieve control are needed.