Handling an outbreak of foodborne pathogens

Even a farm’s water can be tested as a possible contamination source.
Photos by Valeria L. Jefferson, FDA.

When a food poisoning outbreak occurs in the United States, it can cause great fear in the public, but it can also be a huge cause for concern among the agricultural community. Death and widespread illness from pathogens can occur among the public, and huge economic losses to growers and others in the industry can result.

It is the job of Sherri McGarry and many other people at the U.S. Food and Drug Administration, working as a team, to cut through the public panic and confusion that invariably ensues after an outbreak. She is the director of the Division of Public Health and Biostatistics at the FDA’s Center for Food Safety and Applied Nutrition in Maryland. She’s also the center’s foodborne emergency coordinator. When an outbreak occurs, she and her teams, along with other FDA teams, leap into action, engaging in a complex investigation, including tracebacks to the source.

“I’m not a detective, though I do feel like one at times,” says McGarry, a microbiologist and a 17-year veteran at FDA. Pathogens such as salmonella, E. coli and Listeria can be deadly, and her teams treat them like the killers they can be.

The day-to-day work at the center involves a lot of training and planning to prevent, prepare for and respond to contamination in products as varied as packaged spinach, salsa, peanut butter and fresh cantaloupes. Another group that works with McGarry at the FDA does produce surveillance. The FDA learns from each outbreak, and uses research to develop better guidelines for the food industry to follow.

An outbreak notification typically comes from the Centers for Disease Control and Prevention (CDC) in Atlanta, based on information from a state health department. The FDA maintains a liaison at CDC who keeps information flowing. The outbreak may be a cluster of reported cases or sporadic cases spread over a large area, which makes the investigation more difficult. After interviewing people who have become ill, the FDA sends McGarry’s division and others a list of foods that may have been the culprit, along with the pathogen involved. The CDC maintains a data bank of molecular subtypes (or genetic fingerprints) of foodborne disease-causing bacteria that can be compared with the outbreak pathogen. When a food sample and a sick person are found to have bacteria with the same genetic fingerprint, a crucial link is discovered.

This graphic from FDA shows how complex an investigation, in this case of contaminated peanut products, can be.

Basically, FDA teams track the produce backward to its source. This starts with interviews of the infected people by the CDC and state health officials to discover common foods and eating venues. The FDA then obtains records from locations where infected people ate or purchased the suspect food. This can be a difficult process as people try to remember what they ate around the time they first got sick, then recall where they ate out or where they bought the produce. The produce could be fresh or in processed form.

“You need to find out about their food histories,” McGarry says, and the most reliable records are written ones, such as receipts or credit card accounts. Then, the food histories of all the infected people, who may live hundreds of miles apart, must be compared. “We need to find out if they’ve been exposed to the same foods.”

The FDA maintains records of past produce patterns, especially of susceptible foods such as tomatoes and cantaloupes. Once the agency locates the retailer or restaurant where the suspect food was bought or eaten, it then traces the food through the distribution chain looking for a commonality—a common source such as a farm or packing shed. Sometimes, elaborate means are required to trace the suspect food through distribution centers or, in the case of imported foods, foreign governments or importers. The records hopefully lead back to the specific farm where the produce was grown. Of course, mingling of produce—peppers from several sources in salsa, for example—can severely complicate the effort.

Sometimes that farm will be far from the site of the outbreak. For example, the E. coli contamination in spinach in 2006 was felt all over the country, but began in a California farm field. Sometimes the source of the outbreak is outside the U.S. The contamination in the 2008 outbreak of salmonella in jalapeno and serrano peppers, for example, originated on a farm in Mexico.

Once a link is discovered leading to a particular farm, it behooves the grower to have good record-keeping for his crops, because an entire industry—spinach, cantaloupes or whatever—can be held hostage to one farmer’s infected field. Sales can plummet nationally and blame be widespread until that exact source is discovered. “It’s extremely hard to narrow the scope down unless the records help us do that,” McGarry says.

McGarry says that one of the major challenges of FDA’s investigations is the on-farm part. The FDA will send staff, as part of a team, to the farm, including a microbiologist, a water expert and a CDC representative, but they can be slowed by poor record-keeping. She would like to see more farms use electronic record-keeping and tracking means, down to the lot level, because that can help the FDA isolate the problem and move to recovery more quickly. A single field that has been contaminated by means of animal, human or machinery can cause economic losses across the country.

The final stage in the process of getting back to normal is when the industry initiates a recall of the contaminated produce. That is a voluntary process, one in which the industry works closely with FDA, McGarry notes. Visit www.fda.gov/Food/FoodSafety/default.htm for more information.

Andrew Kennedy, president of FoodLogiQ in Durham, N.C., a firm that provides tracking capability to farms and other segments of the food industry, says it isn’t uncommon for many farms to lose a couple of weeks of production when an outbreak occurs in one type of produce. Losses in the agriculture community result from the loss of credibility among consumers.

“The earlier you can pick up the problem, the fewer injuries or deaths,” Kennedy says. “The cost of traceability can be paid back in one recall.”

FoodLogiQ and similar companies advise growers on the methodologies and technologies of traceability, down to the item level. These programs conform to the Produce Traceability Initiative, a 2007 effort by produce industry associations to respond to the 2006 spinach incident. Kennedy notes that a farmer has to have a bar code, as well as on-farm equipment needed to provide labels on his produce packages. It’s a system that can cost as little as $1,000 for a small farm or into the tens of thousands of dollars for large operations. The process all begins at an organization called GS1.

“Their standards have been adopted uniformly across all industries,” Kennedy says of GS1 US, a nonprofit that provides UPC bar codes for a fee. The next stop is an organization called GTIN (Global Trade Item Number), which provides more numbers after the GS1 prefix so a bar code can identify produce right down to lot and item—for example, a bag of oranges or even a single melon. The Web sites for those organizations are www.gs1us.org and www.gtin.info. Then, all that is needed is the labeling equipment.

Kennedy points out there are two levels of farm record-keeping that can facilitate traceability. One is the farm’s internal computer records, wherein special software can be purchased to interface between the company’s internal accounting software and the bar code/labeling software. The second level is special software that can be customized for each farm, and interfaces and shares tracking and labeling information with retailers and other off-farm entities.

A farm that has these two levels of traceability is a dream for the FDA in case of a foodborne disease outbreak, because once a team gets to the farm, it can track the problem pathogen right to the field. It may still be complicated by elements such as farms buying produce from other farms to make up lots for resale. That is why a company such as FoodLogiQ is usually hired to provide an entire record management system and traceability throughout the food chain.

Kennedy notes that U.S. growers are lagging in the installation of such systems. Large operations generally are complying, but only because they must in order to sell to large retail stores that also must comply with traceability standards. Most small and medium-sized farms may be out of compliance. This is a voluntary system, but highly recommended in order to avoid huge disruptions in the produce chain due to slow traceback of contaminated produce. The Produce Traceability Initiative’s goal is to have tracking capability on every case of produce in America, inbound and outbound, by 2012.

Kennedy says the benefits can be tremendous. He recalls a recent salmonella outbreak in cantaloupes from a North Carolina farm that had a good labeling system in place. The packing shed was testing its own produce and discovered contamination. A recall was initiated well before public health was compromised, and the issue was taken care of internally. Thus, traceability and testing in tandem provide an ideal mechanism for food safety and a reduction of farm risk.

Kennedy notes that, in his experience, only a small percentage of growers even know about the initiative and the traceability options, and even fewer are compliant. A small survey in North Carolina in early 2009 revealed that only about 5 percent of those growers surveyed were compliant, and those were large growers who had to be in order to sell to retail chains.

“There are some people who are throwing up their hands at this” because of the expense and complexity, Kennedy says, but this is the future, and growers who want to be there with their produce are beginning to comply. The smart ones, Kennedy says, see it as an opportunity to modernize and provide their farms entrée into a produce supply system that is ever more aware of the needs for food safety and traceability.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.