Certain food borne diseases are "reportable" illnesses; that is, a lab diagnosis of the illness must be reported by medical practitioners to health authorities. In 1998, CDC inaugurated a system known as PulseNet, which receives information, including genetic fingerprints, on all of the reported cases in the United States. Since its inception, PulseNet has gone international, sharing data and genetic fingerprints cooperatively with many countries around the world.
US outbreaks of food borne diseases – Salmonella, Listeria monocytogenes, E. coli O157:H7, Campylobacter, and Shigella – are recognized when CDC spots one or more clusters of cases that have a common genetic fingerprint. CDC then works with health investigators in the affected states to determine whether an outbreak is underway and to find its source.
If the source of the outbreak appears to be a food that is regulated by the FDA, that agency is called in. Likewise, the USDA becomes involved if the suspect product is regulated by that department. State departments of health and agriculture in those states where outbreak cases have been detected also participate in the investigation.
There are several points at which this multi-layered system for spotting outbreaks can bog down.
- Food poisoning victims often do not seek medical attention. Most mild cases of illness never are reported.
- Doctors do not always ask their patients to provide stool samples for lab analysis. Without lab analysis, cases go unreported.
- Not all states are equally well equipped with facilities for genetic fingerprinting of pathogens. Clinical labs in these states may have to ship their cultures to another state for fingerprinting, causing reporting delays.
- There may be delays in reporting information to PulseNet.
- Overburdened staff at CDC (and its international partners) may not spot connections between individual cases from different geographic locations, until an outbreak has produced several illnesses from a single location.
Certain of these bottlenecks are difficult to remove. Someone with a mild case of gastroenteritis is unlikely to visit a doctor or clinic just to satisfy the needs of a national health surveillance system. But we would like to propose a couple of suggestions that might make a difference
- Determine which states lack adequate facilities for carrying out full genetic fingerprint analysis of food borne pathogens, and provide federal funds to equip, staff, train, and maintain one such facility in each of these states.
- Review the procedures for submitting information to PulseNet and make any necessary adjustments so that the process is as simple and user-friendly as possible.
- Share real-time access to PulseNet data with the food safety community outside of government agencies.
Data sharing would allow outside parties to help spot incipient outbreaks and flag them to CDC for more careful screening. Some college professors might use PulseNet as a teaching aid, or assign class projects based on the data base. And microbiology-savvy bloggers – including yours truly – could monitor PulseNet on a regular basis, supplementing the resources available for detecting outbreaks, without any additional cost to the CDC.
In this age of instant information access, it would be wise for the Food Safety Working Group and CDC to examine ways to take advantage of outside expertise to supplement internal resources.