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Gastroenteritis Outbreak Investigative Guidelines

Investigation Method

1) Collect preliminary data, specifically

  • are there > 2 non-householders with gastroenteritis?
  • what are the percentages of:
    • vomiting?
    • diarrhea?
    • severe abdominal cramps?
    • fever?
  • where did the > 2 non-householders eat?
  • when did they eat (date and time)?
  • when did they start vomiting or experiencing diarrhea (date and time)?
  • what did they eat?
  • with whom did they eat?
  • did they share other meals in the past week?

2) Call ACDP at 971-673-1111 for referral, if indicated, to the ACDP Urgent Epidemiologic Response Team (UERT).

3) Specimens

  • Give outbreak-affected persons Instructions for Collecting Stools for Viral Culture and PCR (pdf)
  • Use secure, leak-proof containers with screw tops, not flip tops, labeled with name, collection date, and outbreak number.
  • Collect specimens of walnut-size stool, 3 tbsp of diarrheal stool (or vomitus) or 3-4 rectal swabs from five outbreak-affected persons up to four days after onset. Collecting >5 does not increase the chance of finding something.
  • Remember that two positives are required to "confirm" the microbial cause of an outbreak. The Oregon State Public Health Laboratory will not test just a single specimen.
  • Based on epi curve and symptom profile, determine whether the etiology is likely to be viral or bacterial.* Complete instructions for specimen submission are available on the OSPHL Lab Test Menu at
    • If likely to be viral, follow the instructions above for collecting stool specimens for viral culture and PCR. Choose the OSPHL Lab Test Menu listing for "Viral Gastroenteritis Panel, PT-PCR".
    • If likely to be bacterial, collect stool specimen in a Cary Blair transport media. Choose the OSPHL Lab Test Menu listing for “Enteric Pathogen Culture, Bacterial".
  • If additional testing is thought to be warranted, consult with ACDP regarding possible bacterial culture or multiplex PCR testing at OSPHL.

4) Complete record in Outbreak database

  • Submit no later than 30 days after the onset of the last case

*If the sample is submitted for noroviral testing, OSPHL will no longer test for other viruses or perform reflex culture for bacterial pathogens if the test for Norovirus is negative. Consult ACDP if you believe that further testing is warranted.

Special Situations

Definition, suspect foodborne outbreak

  • > 2 non-householders who develop gastroenteritis (acute onset vomiting, diarrhea or both) at about the same time after eating food from the same source

Investigative authority

  • ORS 333-018-0015 authorizes local health departments to investigate foodborne and other common source outbreaks by requiring health care providers to report all such suspected outbreaks immediately.  
  • ORS 333-019-0010 imposes work restrictions on persons who work at food service facilities whilst in a communicable stage of any illness accompanied by diarrhea or vomiting.
  • ORS 624-080 authorizes local health departments to collect stool specimens from food handlers.