Outline the investigation of a foodborne illness outbreak.

Routine monitoring of important diseases by public health departments is called disease surveillance. Each state decides which diseases are to be under surveillance in that state. In most states, diagnosed cases of salmonellosis, E. coli O157:H7 and other serious infections are routinely reported to the health department.The county reports them to the state health department, which then reports them to CDC.Tens of thousands of cases of these "notifiable conditions" are reported every year. For example, nearly 35,000 cases of Salmonella infections were reported to CDC in 1998. However, most foodborne infections go undiagnosed and unreported, either because the ill person does not see a doctor, or the doctor does not make a specific diagnosis. Also, infections with some microbes are not reportable in the first place.

When a foodborne illness outbreak has been defined, the local health department begins a prompt epidemiological, task-oriented investigation. Investigation procedures should follow those outlined in the IAMFES Procedures to Investigate Foodborne Illness book:

1. Case history interviews
   1. Collect additional case history information to supplement any previously collected information.
   2. Advise ill persons to seek medical attention if they have not already done so.
2. Evaluation of the foodservice establishment.
   1. Inspect the foodservice establishment by interviewing foodservice personnel regarding food sources, preparation methods, storage, display, and transportation used at the time of the suspect meal.
   2. Review the facility's food handling practices, personal hygiene, equipment operation, pest control, illness reports, plumbing, proper waste disposal, and water supply.
   3. If possible, obtain an attendance list for the suspect meal.
3. Collection of suspect food
   1. Collect a sample of each food from the suspect meal, if available, for laboratory analysis of the suspected pathogen.
   2. Clearly label and refrigerate samples at 41°F or colder; store in a secure location to avoid accidental use.
4. Collection of clinical specimens
   1. Share pertinent investigation information with the medical personnel involved.
   2. Collect samples from exposed persons and food handlers based on professional judgment or when ordered by medical director.
5. Summary and report preparation
   1. Prepare a report summarizing the findings of the investigation, test results, and any corrective action necessary to protect the public health.

Source:
IAMFES Procedures to Investigate Foodborne Illness

If you have questions, contact Dr. Angela Fraser, Associate Professor/Food Safety Education Specialist, Clemson University, Clemson, SC.

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