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Tracking Down the Source of Outbreaks: It’s Complicated

Meet CORE, FDA's team of food safety sleuths

At an FDA lab in Denver, Microbiologist Melissa Nucci preps for testing peanut butter samples for Salmonella. Photo courtesy of FDA’s flickr.

With a globalized food supply brought to us by increasingly complex supply chains, foodborne illness outbreaks are notoriously tough to solve. These outbreaks often involve multiple states and dozens of illnesses, which are chronically underreported. They include patients who can’t remember what they ate for lunch last week, and, while food products are often narrowed down to a list of possible culprits, nine times out of 10 we will never know which one was to blame.

The outbreaks we hear about – and that Food Safety News reports on – are usually the ones that were solved, meaning federal, state, and local health officials were able to put all the evidence together, pinpoint a food source, and alert the public with an outbreak announcement from the federal Centers for Disease Control and Prevention or maybe even a recall from the U.S. Food and Drug Administration. But an extraordinary amount of work goes into trying to crack these cases, whether the public hears about them or not.

That’s where FDA’s elite team of investigators comes in. This cohort – formally known as the Coordinated Outbreak Response and Evaluation Network – has been working tirelessly on foodborne illness outbreaks since the initiative launched two years ago this month.

Designed for more rapid response, CORE brings together epidemiologists, microbiologists, veterinarians and other experts, all under the same roof at FDA so they can work together more efficiently and focus solely on outbreaks.

In interviews, CORE staff often use terms such as “more efficient,” “better structured,” “more effective,”  “faster” and “better organized” to describe the shift to a consolidated team. But one of the biggest changes, according to FDA officials, is that CORE puts a fresh focus on learning from each incident and applying those lessons toward more preventive policies and practices.

Before CORE, FDA only had seven or eight people to do outbreak response within the Center for Food Safety and Applied Nutrition, according to microbiologist Elisa Eliot, a 24-year veteran of FDA who now works at CORE.

“We didn’t have people out there really evaluating information, looking for outbreaks, and working proactively with CDC. Sometimes we’d get together in a work group, but it wasn’t an ongoing, continuing, day-to-day activity,” Eliot recalls. “We didn’t have the people power to look back and do a lot of the ‘lessons learned’ and come up with preventive, better practices. We were more in the response mode all the time.”

CORE, which now has a staff of more than 30 (including contractors), is divided into three parts to help ensure prevention is not lost in the shuffle: Signals and Surveillance, which works closely with CDC to identify any emerging outbreaks that might be linked to an FDA-regulated product; Response, which is comprised of separate teams that coordinate the response efforts on multiple foodborne illness outbreaks; and Post-Response, a team solely dedicated to gleaning what is learned from each outbreak and applying it.

Tip of the iceberg

In the past two years, CORE has been repeatedly tested with an onslaught of foodborne illness outbreaks, only a fraction of which ever made headlines.

“It’s seasonal for us, as outbreaks tend to be,” said Ashley Grant, an epidemiologist for the Signals team. “Right now, we are in the peak of our season, so we probably have about eight to 10 on our plate at any given time in summer and spring months. As we get into the fall and winter, we probably have about five a week.”

Between August 2011 and the end of 2012, for example, the CORE Signals team evaluated 211 incidents, 63 of which were transferred to a Response team. During that time frame, however, only 12 outbreaks were announced on the FDA Website.

Of all the incidents CORE Signals tracked during that time, 144 were not referred to a Response team. According to FDA, in 22 of those cases, the vehicle turned out not to be an FDA-regulated product (remember that meat, poultry and processed eggs fall under the jurisdiction of the U.S. Department of Agriculture). The agency said that in another 34 cases, “FDA response activities had already been initiated and completed,” which means the case might be handled outside of CORE by the enforcement branch or at the state level. In the remaining 88 cases, the vehicle was not identified.

Staying on top of all this is a lot of work. CORE staff are known to work long hours and weekends when they’re assigned to an outbreak that’s particularly tricky.

The slow-moving nature of foodborne illness reporting, which suffers from lag times, underreporting and diminishing public health resources at the state and local levels, adds another layer to an already complicated puzzle.

“Sometimes, the outbreak has concluded by the time we’re actually getting to the point where we have an idea of what the vehicle might have been,” said Jennifer Beal, an epidemiologist for the Signals team. “In that case, there’s nothing left for the response team to do.”

“Other times, the vehicle is never identified and that probably constitutes the bulk of the cases we don’t transfer [to the Response team],” she added. “But for any one of these things, we put in the same amount of effort to try to determine the vehicle.”

The team still pours a lot of time and energy into trying to figure out what the cause of a foodborne illness outbreak might have been. When they aren’t successful, they still save the information gathered in case a similar situation arises.

According to Gary Weber, a CORE supervisory interdisciplinary specialist in animal science, each and every incident is “pushed as far as this team can take them to find out the linkages.”

“They don’t give up easily, that’s for sure,” he added.

Frustration over the unexplained

CORE Network Team leaders from left: Jeffrey Brown (Signals and Surveillance Team), Carla Tuite (Response Team), Brett Podoski (Post-Response Team), Pamela LeBlanc (Response Team) and William Lanier (Response Team). Photo courtesy of FDA’s flickr.

When meeting with CORE investigators, the passion they have for their work and for public health is evident, but so is their frustration over the outbreaks that could not be explained, despite intense, lengthy investigations.

For Roberta Hammond, a CORE supervisory interdisciplinary scientist, it’s often the multiple-ingredient outbreaks that cause heartbreak — when investigators can narrow the source to a salad mix or a restaurant chain but are unable to take it one step further to figure out which ingredient.

Even when they do figure out the vehicle in time, comingling and lot mixing, especially for produce, can complicate things.

“Something with a short shelf life is more challenging because there may not be product to sample, or if you do manage to trace it back to the firm or farm or field, it’s not there,” said Pamela LeBlanc, a leader of one of the CORE Response teams.

Stelios Viazis, a microbiologist for one of CORE’s response teams, agrees: “That’s the most frustrating.”

These are increasingly factors in foodborne illness outbreaks as Americans increase their year-round appetite for fresh and even raw foods from a variety of sources, both domestic and foreign.

Looking back at tuna scrape

Most consumers have never heard of tuna scrape – it’s tuna meat that has been scraped or mechanically separated from the bone, resulting in a slurry of fish meat – but it is commonly used to make inexpensive sushi. This is a prime example of what foodborne illness investigators call a “stealth ingredient.”

Last year, when Salmonella Bareilly and Nchanga infections started cropping up in several states, investigators quickly honed in on sushi, but they were stumped by which ingredient was responsible.

The CORE team recalls spending “a lot of time doing an ingredient matrix.”

For a while, they thought it might be the hot sauce mixed into spicy tuna rolls, as many people sickened had reported eating them.

Investigators pursued the hot sauce, with no luck, and there were many other ingredients to look at: sesame seeds, seaweed paper, rice, mayo or another sauce mixed in with the tuna, or even spices that were added into the mix.

As they started investigating tuna scrape, CORE investigators realized there was no common language for invoicing the product – the scrape could be labeled any number of things. Making matters more difficult, many of the restaurants also used Cash and Carry or bought ingredients from sources with no receipts or paper trails. Plenty of businesses linked to the outbreak didn’t know where their tuna product came from.

“It wasn’t labeled,” recalls Dr. Kathy Gensheimer, the chief medical officer and director of CORE. “We had someone from the Bronx who just bought this stuff off the back of a pickup truck.”

When approached by FDA, many restaurant owners also insisted they only used fresh tuna, not the lower-quality frozen scrape – even when they did – adding yet another layer to the investigation.

It ended up taking CORE about a month – bringing nearly 30 extra people into an emergency operations center to work on traceback for three weeks – to definitively link the outbreak to the scrape. Officials had to sort through thousands of pages of documents and map out each complicated supply chain, which are really more like webs.

The traceback map from that investigation is a flow chart that looks “like a circuit board,” as FDA spokesman Doug Karas puts it.

That outbreak, which ultimately sickened 425 people in 28 states, showed that “with enough resources, you can get to the bottom of anything,” Gensheimer said.

“A month may sound like a horrendously long time for people getting sick,” she said, but FDA’s effort paid off in terms of public health. Once a recall was initiated, 58,000 pounds of the contaminated scrape was taken off the market.

“That would have made a lot of sushi rolls,” Gensheimer noted, adding that the product showed an unusually high level of contamination. “Just about every sample we were pulling yielded Slamonella Bareilly and Nchanga.”

If you assume a sushi roll contained a few ounces per roll of a very contaminated product, FDA’s work likely prevented thousands of diners from eating the Salmonella-ridden pink paste.

“I think you can multiply that 500 cases many, many, more times. I think we would have had thousands of cases nationwide, and even internationally, because of course this is a global trade,” Gensheimer said.

New focus on prevention

During a series of interviews with CORE officials, prevention was a common theme. Investigators repeatedly said one of the best parts about the way CORE is organized is that it dedicates a team to learning from outbreaks and following up on investigators’ recommendations.

“Now we really take the time for every single outbreak to figure out: Is there something we could have done better? Even if it’s not us – even if it’s a policy or a practice – that’s just never been done before,” explains Carla Tuite, a leader of one of CORE’s Response teams.

CORE’s Post-Response team kicks in right as the outbreak is winding down, regardless of the size or scale of the incident. If investigators ran into roadblocks – perhaps a trading partner wasn’t cooperating, for example – this team follows up on those problems.

“It’s the follow-through that takes place that has really made a big impact,” said Kari Irvin, a leader of a Response team. Irvin explained that Post-Response might include follow-up inspections or specific policy recommendations.

“If we think it’s a larger industry problem, we might work with an industry association,” said Katherine Vierk, who works on Post-Response for CORE.  “[The team] might discuss whether there needs to be additional guidance, or if this issue needs to be considered in an upcoming guidance document.”

Vierk said the Post-Response teams also reach out to the people working on rolling out and implementing the Food Safety Modernization Act, the country’s new food safety law.

If poor record-keeping was a particularly thorny issue during an investigation, it would be the Post-Response team’s job to give feedback to the FSMA rulemaking experts and tell them what would have been helpful.

Or, let’s say that the Response teams didn’t ask for the right records. If that were the case, the Post-Response team would try to figure out a way to improve their internal process.

According to Vierk, CORE is expecting to look more toward environmental assessments in the future.

“Getting out there to find out the true environmental antecedents, the true reasons why contamination occurred and then exploring ways to get that information back to industry so it doesn’t happen to them,” is a top priority, she said.

CORE points to Jensen Farms as a great example of translating knowledge into better practices. What was learned in that Listeria monocytogenes outbreak in late 2011 is now informing preventive practices at the farm level. For produce, FDA puts together PowerPoint presentations based on what CORE has learned from various outbreaks, and those are disseminated through extension agents in different states. That knowledge, according to Vierk, is helping growers learn from others’ mistakes.

Before CORE, such prevention efforts were made on an ad hoc basis as people would flag things, but now the agency has dedicated staff to do that work.

FDA is also able to prevent more illnesses because CORE gets involved with foodborne illness investigations more quickly now than in years past, giving the agency a better shot at removing contaminated product before it’s consumed.

Before CORE was launched, CDC would determine that there was a foodborne illness, and then, once they figured out it might be related to an FDA-regulated product such as cheese or lettuce, “they would literally toss it over like a volleyball net and FDA could then pick up their piece and run with it,” explains Gensheimer, who oversees CORE at FDA.

“If you’re sitting there waiting for all that work to be done, the lettuce is long gone or the cheese has been eaten,” she said.

“We get involved earlier now,” she added. The Signals team now actively monitors consumer complaints, talks to states, and keeps an eye on PulseNet, CDC’s surveillance network.

“Instead of that volleyball-net mentality, we’re all engaged with the states really almost from the get-go. It’s a cobweb interface, it’s constant communication back and forth and hopefully getting us where we need to be more quickly,” Gensheimer said.

Cyclospora outbreak rolls on

Despite all the focus on improving foodborne illness outbreak response, FDA has come under fire recently for what many consider a painfully slow response to the ongoing Cyclospora outbreak.

At last count, 548 people in 19 states have fallen ill with the parasite. In an update issued this week the FDA said, “we are moving quickly to learn as much as possible and prevent additional people from becoming ill.”

But food safety experts have questioned why federal officials have still not figured out which product caused all of these illnesses, or even if all the illnesses are related to one another. A few weeks ago, Iowa and Nebraska identified an unnamed salad mix as the source, but both FDA and CDC have continued to say they are pursuing multiple leads, insinuating that the conclusions drawn by those two states are just part of the picture.

FDA has since confirmed that the salad mix grown by Taylor Farms de Mexico and served at Olive Garden and Red Lobster restaurants in Iowa and Nebraska is indeed linked to the illnesses in those states, but the question is why haven’t federal officials been able to solve the larger outbreak?

David Steigman, an FDA spokesman, declined to answer questions about how many separate supply chains the agency might be investigating because the investigation is still ongoing.

“It is not yet clear whether the cases reported from other states are all part of the same outbreak,” Steigman said.

Larry Slutsker, director of CDC’s Division of Parasitic Diseases and Malaria, told Food Safety News that part of the problem is that the agency lacks the technology to quickly differentiate which Cyclospora infections are related.

“The ability to determine subtypes, also known as strain differentiation, of foodborne pathogens would be an invaluable tool in foodborne outbreaks like this,” he said. “Subtyping supplements epidemiologic and traceback information so we’re better able to tell how cases or clusters of cases may – or may not – be related to each other. Unfortunately, this process is much less well-developed for parasites when compared to bacteria such as Salmonella or E. coli.”

FDA said Monday the traceback process for the current Cyclospora outbreak is “labor-intensive and painstaking work” that involves thousands of documents. The agency said it has a 21-person team focused on the outbreak at headquarters, with another 10-person staff working in the field, but there are still no answers as the outbreak rolls toward its eighth week.

© Food Safety News
  • Gatorville28

    Wonderful information! It’s good to see the Feds are making an exerted effort to get a handle on the ever growing epidemic of food bourne illnesses. Keep up the good work CORE!