Investigation Method
Local Public Health Authority (LPHA) will initiate investigation within 24 hours of learning of suspected outbreak
1) Collect preliminary data
- are there > 2 non-householders with gastroenteritis and shared exposure (e.g., restaurant, potluck, petting zoo, rodeo, etc.)?
- what percentage of affected individuals report:
- vomiting?
- diarrhea?
- severe abdominal cramps?
- fever?
- when did they start vomiting or experiencing diarrhea (date and time)?
- what was the duration of gastrointestinal symptoms (number of days or hours)?
- Collect as much detail as possible on the nature of the shared exposure for the affected individuals; for instance, if food exposure is suspected:
- where did they eat?
- when did they eat (date and time)?
- what did they eat?
- who did they eat with?
- did they share other meals with other affected individuals in the past week?
2) Call ACDP at 971-673-1111 to report outbreak within 24 hours of learning of the outbreak. An outbreak record will be created and 2 members of the ACDP Urgent Epidemiologic Response Team (UERT) will be assigned to support LPHA with investigation.
- Assigned UERT epidemiologists are available to consult with LPHA on questions regarding specimen collection, questionnaire development, communications, or other needs as they arise.
- LPHA will obtain details for suspected outbreak source (e.g., patron information and menus for suspected restaurant-associated outbreaks, coordinating with their Environmental Health Program and UERT epidemiologists as needed).
- Expand the investigation with UERT assistance and in accordance with Outbreak Investigation guidelines (pdf).
3) Specimens
- Specimen collection kits can be requested directly from Oregon State Public Health Library (Click on “Notify OSPHL” button in Etiology tab of outbreak record to initiate request).
- Prior to shipping specimens, ensure that containers are secured to prevent any leaks and labeled with name, collection date, and outbreak number (OSPHL will reject specimens that are not labelled with this information).
- Collect specimens of walnut-size stool, 3 tbsp of diarrheal stool (or vomitus) from five outbreak-affected persons up to four days after onset. Collecting >5 specimens does not increase the chance identifying pathogen.
- Remember that at least two positives specimens are required to "confirm" the outbreak etiology. The Oregon State Public Health Laboratory will typically not test just a single specimen.
- If needed, provide affected individuals with Instructions for Collecting Stools for Viral Culture and PCR (pdf).
- Use preliminary data from symptom profile to generate epi curve and ascertain, whether the etiology is likely to be viral or bacterial.* Complete instructions for specimen submission are available on the OSPHL Lab Test Menu at www.healthoregon.org/labtests. Consult with and obtain approval from UERT epidemiologists before submitting specimens to OSPHL.
- If likely to be viral, choose the OSPHL Lab Test Menu listing for "Norovirus, Real-Time, RT-PCR" (includes Astrovirus; Calicivirus; Norovirus (I and II); Sapovirus; Rotavirus; Gastrointestinal Viruses; Norwalk) and follow instructions.
- If likely to be bacterial, choose the OSPHL Lab Test Menu listing for “Enteric Pathogen Culture, Bacterial" and follow instructions.
- If a suspected etiology is unclear, choose the OSPHL Lab Test Menu listing for BioFire FilmArray Multiplex Gastrointestinal PCR Panel) and follow instructions.
- If additional testing (e.g. food, animal, environmental) is thought to be warranted with assigned UERT epidemiologists.
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.