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Long-Term Care Facilities Investigative Guidelines
nurse and woman


Updated Control Measures and Norovirus Outbreak Detection and Management Tool now available.   

Mandatory Outbreak Reporting


  • Acute gastroenteritis (AGE): acute-onset vomiting, diarrhea, or both without another apparent cause.
  • AGE outbreaks in LTCFs and hospitals: 
    • General definition: an "unusual" number of patients, residents or employees with AGE clustered by time and place 
    • Working definition: two or more patients, residents or employees in the same LTCF or on the same hospital unit with AGE onset dates within 96 hours of each other (two incubation periods of most gastroenteritis agents) of each other
    • Lab-confirmed AGE outbreak: 2+ stool samples that test positive for the same pathogen
    • "Unexplained" AGE outbreak: 4+ stool samples that test negative for any pathogen (all unexplained AGE outbreaks will now be tested for sapovirus, a Calicivirus similar to norovirus)


Control Measures

Stool Samples

  • Collect up to 5 stool samples until the etiologic agent is laboratory-confirmed with >2 positive samples or until >4 samples are negative. Stool samples collected by LTCFs and hospitals and tested at commercial laboratories count toward the five-stool target.
  • Follow: The Stool Sample Kit: Instructions for [Local Health] Staff (pdf).
  • Order "Enteric Outbreak Stool Sample Kits" (AKA "It Kits") from the state public health lab. Consider arranging for LTCFs and hospitals to stock up on "It Kits" before they have outbreaks.

Data Collection and Basic Descriptive Epidemiology

  • Use one Gastroenteritis Case Log (pdf) per outbreak-affected unit. The log can be completed by LTCF or hospital infection control staff; establishing a single point of contact is recommended. 
  • Ask that the Gastroenteritis Case Log (pdf) be completed on the first 10 or more cases  for whom demographics, time of onset, and symptom profile can be obtained. Use this information to determine the likely cause of the outbreak and to assess the likelihood of point-source transmission (for example, a shared meal). 

  • If the symptom profile is consistent with norovirus (vomiting and diarrhea with minimal fever and no blood in stool) and the epi curve is not consistent with a point-source transmission, record any new cases in the Gastroenteritis Case Log (pdf) with the case’s name and date of illness onset. Monitor daily until no more cases occur. If the outbreak is not noro-like or suggests point-source transmission, please call the Epi On-Call at 971-673-1111.

  • Enter case log data in the ACDP GI Case Log Database available via Citrix through the “Directory of Useful Databases for Epidemiologists” (DUDE). For a CDC project attempting near-real time reporting of norovirus-like outbreaks, case log data from the early days of the outbreak should be entered no later than five days after the outbreak is reported to ACDP,
  • Use the tools included in the database to get basic descriptive epidemiology, including an epidemic curve (i.e., cases by onset time) as soon as new data are entered.
  •  Monitor the outbreak until the last case has been symptom-free for 48 hours (this is when the outbreak is considered “over”).
  • Complete a Control Measures Report (pdf) and enter the report in the ACDP Control Measures Report Database available via Citrix through the “Directory of Useful Databases for Epidemiologists” (DUDE).       

  • Within 30 days of the onset date of the last case, enter summary reports of the outbreak investigation in the ACDP Outbreak Database available via Citrix through the “Directory of Useful Databases for Epidemiologists” (DUDE).
  • Refer to Norovirus Outbreak Detection and Management Tool: Instructions for Long-Term Care Facilities (pdf).