Spike in foodborne outbreaks highlights need for improvements

Approximately one in six people are infected with a foodborne illness each year in the United States, according to the CDC. The costs of foodborne illness are vast; Salmonella alone has accounted for $365 million in direct medical costs.

Recent outbreaks in 2011 have highlighted the need for improvements in the system — outbreak reporting and diagnosing illness in patients must improve. However, in some instances, positive outcomes have been demonstrated. The quick response time in the Listeria outbreak led to the swift identification of the food vector, which was promptly removed from the market.

“The tragic deaths and illnesses resulting from consumption of cantaloupes contaminated with Listeria underscore the need to continually improve food safety,” Michael R. Taylor, JD, deputy commission for foods at the FDA, told Infectious Diseases in Children. “The Food Safety Modernization Act (FSMA) presents a historic opportunity to build a food safety system based on preventing foodborne illness outbreaks and reducing the public health impact of those that do occur.”

The springtime outbreak of Escherichia coli in Germany was deadly. Germany’s Robert Koch Institute reported that as of July 5, there were 852 cases and 32 deaths from hemolytic uremic syndrome associated with Shiga toxin-producing E. coli (STEC) infections.

“The German strain was a combination of two potentially lethal strains — Shiga toxin-producing E. coli plus an enteroaggregative E. coli — making it a new and more lethal organism,” Herbert L. DuPont, MD, chief of medicine at St. Luke’s Episcopal Hospital in Houston, director of the Center for Infectious Diseases at the University of Texas School of Public Health in Houston, said in an interview. “We don’t know if the organism will become an AIDS-like problem or like severe acute respiratory syndrome (SARS) that threatened public health in 2003 and then disappeared. We will have to watch closely whether this

E. coli strain becomes endemic and widespread.”

Evolving organisms

The German strain is an uncommon E. coli serotype, which may not be detected by many laboratories.

“Almost half of Shiga toxin-producing E. coli is non-O157:H7,” DuPont said. “We need to test stool samples directly for Shiga toxin followed by serotype studies of E. coli for positive strains to find them.” If this particular strain becomes endemic, it could become “an important cause of kidney disease and death.”

There have been six confirmed cases of STEC O104:H4 infections in the United States associated with the outbreak in Germany. The Robert Koch Institute identified the likely infection source as contaminated raw sprouts from a single German farm.

The outbreak highlighted the need for improvements in the German outbreak surveillance system. “This was clearly an investigation that could’ve been done a lot faster by people with more experience conducting these types of investigations and with a better surveillance system,” William E. Keene, PhD, MPH, senior epidemiologist of the Oregon Public Health Division, told Infectious Diseases in Children.

Listeria monocytogenes outbreak

At the end of August, reports began to surface about a Listeria monocytogenes outbreak. Investigations revealed that the outbreak source was whole cantaloupe grown at Jensen Farms’ fields in Granada, Colo. This outbreak affected 133 people across 26 states, with 28 deaths.

“This is the deadliest outbreak of a foodborne disease that we’ve identified in more than a decade,” Thomas R. Frieden, MD, MPH, director of the CDC, said during a recent media briefing. “This is a reflection of the fact that Listeria has a high mortality rate for people who are highly susceptible. The vehicle was rapidly identified through a collaborative effort between the Colorado Health Department along with [the CDC] and FDA to be a single producer of cantaloupe from Jensen Farms.”

“We’re still following this outbreak closely,” Ian Williams, PhD, MS, chief of the outbreak response and prevention branch at the CDC, told Infectious Diseases in Children. “We found the source of the contamination, and that’s off the market. But, unfortunately, the incubation period for Listeria can be upward of 2 months. Typically, the average is shorter than that. Hopefully, we’re past the peak and down the other side.”

Increase in multistate outbreaks

Overall data indicate that the number of multistate outbreaks is rising. Last year, there were nine multistate outbreaks. According to CDC data, there were 12 outbreaks in 2010, six in 2009, four in 2008, five in 2007 and three in 2006.

According to Williams, there are a few reasons why the rates are rising. First, tracking multistate outbreaks has improved. “We’re finding outbreaks that may have been there all along, but we hadn’t seen them before,” he said.

“In the last couple of years, we’ve been getting somewhere between 50,000 and 60,000 isolates into the CDC,” he said. “This tremendous stream of data is starting to flow in, and we’re starting to get a good idea of what things are common and what is unusual. We’re seeing these clusters of cases that need to be investigated.”

Another reason for the rising outbreak rates is the centralization and industrialization of the food supply, according to Williams. More often, large, multinational corporations are producing the food supply. This does not necessarily mean that the food supply is any less safe, “but what it means is that if there is a problem in the food supply, it can be rapidly amplified through the system. If there’s a problem in [one] facility, it’s suddenly a problem in 20 states,” he said.

The third issue is the globalization of the food supply. “We rely on countries outside the United States to produce safe food, and that doesn’t always happen,” Williams said. “I studied a cantaloupe outbreak a few years ago. The cantaloupe came from a Central American country. Those cantaloupes were on people’s tables [in the US] within 5 days. If there’s a problem in a facility in another country, it can rapidly become a problem here in the United States.”

Tracking bacteria

In its fight against foodborne disease outbreaks, the CDC utilizes two programs: PulseNet and FoodNet.

First, the agency identifies outbreaks through PulseNet. The laboratories in this national network perform DNA fingerprinting of people with illnesses that may be associated with food. Coordinated by the CDC, the network includes state and local health departments and federal agencies.

Participants use pulsed-field gel electrophoresis to obtain the DNA fingerprints of disease-causing bacteria and then send them electronically to a CDC database. The goal is to detect foodborne disease outbreaks early.

“[PulseNet] is critically important to what we do,” Keene said. Before PulseNet, epidemiologists found it difficult to identify national outbreaks unless they were vast or involved some rare disease serotype.

In the Listeria outbreak, PulseNet helped to identify the outbreak early, allowing officials to pinpoint the food vector — in this case, cantaloupe — and remove the product from the market. “It was a big success story,” Williams said. “They figured it out quickly and conducted a recall and prevented illnesses.”

The agency tracks these foodborne diseases through FoodNet, which permits active surveillance for foodborne illnesses and related studies, according to the CDC. It is a collaborative effort on the part of the CDC, 10 state health departments (California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon and Tennessee), the USDA and FDA.

FSMA and CORE

With the passage of the FSMA in January 2011, the CDC aims to improve the foodborne outbreak outlook as well. The act gives the CDC the responsibility to improve federal, state and local surveillance systems, allowing the agency to identify and control outbreaks more quickly while learning how to prevent future outbreaks.

“The FDA is working diligently to draft proposed regulations to implement FSMA, including ones to establish modern preventive control measures for food and feed facilities and mandatory science-based, minimum standards for the safe production and harvesting of fruits and vegetables,” Taylor said. “Prevention of food safety problems must be the norm.”

In May, the FDA issued the first two rules under the FSMA. The first rule allows the FDA the authority to detain food if the agency determines that it has been produced under unsanitary or unsafe conditions. The second rule mandates that food importers alert the FDA if any country has refused entry to the product, including pet food.

Recently, the FDA launched two pilot projects under the act. One will focus on processed food and the other will focus on produce. Both projects will assess methods and technologies for rapid, effective food tracing, ways to connect various points in the supply chain and how quickly the FDA receives the data.

In September, the FDA established a foodborne illness outbreak response group, dubbed the Coordinated Outbreak Response and Evaluation (CORE) Network. The goal is to manage outbreak response, as well as surveillance and post-response activities related to foodborne disease. This streamlined, integrated approach aims to permit effective and rapid responses to human and animal foodborne illness outbreaks.

The network includes a multidisciplinary team of epidemiologists, veterinarians, microbiologists, environmental health specialists, emergency coordinators and risk communication specialists. During an outbreak, the CORE Network will coordinate with the CDC, the USDA and state public health and agriculture agencies.

“By having a full-time staff to prepare for, coordinate and carry out response to incidents, we can improve response time and standardize our procedures and activities,” said Kathleen F. Gensheimer, MD, MPH, chief medical officer and CORE’s outbreak director. “By having a centralized, full-time staff dedicated to post-response activities (currently spread out across various FDA offices), we can concentrate more on lessons learned, to try and prevent incidents in the future and incorporate what we’ve learned into more effective, preventive food safety practices and policies. Many of those efforts will be enhanced by working collaboratively with our many partners at the local, state, federal and international level. IDSA represents a critical partner in this work.”

Improvements needed

Improvements are needed, beginning with better reporting. “It has to do with resources at the state and local level,” Williams said. “A lot has to do with taking the system and making sure that when people get diagnosed, things get into the system, they get tested appropriately and they are forwarded to the CDC. There are a number of things that can be done to strengthen the overall surveillance system.”

“Better public health investigations give the media, the regulatory agencies that look at the reports and those of us who generate the results a better understanding of what’s important,” Keene said, adding that those who investigate outbreaks need enough samples to obtain an accurate view of the situation.

More investigations increase the understanding of what causes these illnesses and, hopefully, suggest how to prevent them or how to reduce the occurrence and decrease the severity.

“It’s a paradox: The more outbreaks you identify, the better your public health system is functioning,” Keene said.

Getting more people diagnosed is important, too. “We estimate that for Salmonella, for every case that we see in our surveillance system, that there are 30 more cases that we don’t see,” Williams said. Improving diagnosis involves equipping the front-line people — the doctors and nurses at hospitals — with the proper tools, as well as teaching them how to diagnose and collect the appropriate specimens, he added.

To help with diagnosis, there are better microbiologic methods available to detect pathogens in those with enteric illnesses, such as widespread stool screening that looks for Shiga toxin to identify non-O157 strains, other causes such as enteraggregative E. coli or new viral pathogens, DuPont said. – by Colleen Owens

For more information:

• CDC. FoodNet surveillance — What is FoodNet? Available at: www.cdc.gov/FoodNet/surveillance_pages/whatisfoodnet.htm. Accessed Dec. 15, 2011.
• CDC. Incidence of foodborne illness, 2010. Available at: http://www.cdc.gov/Features/dsFoodborneIllness/borneIllness/. Accessed Dec. 15, 2011.
• CDC. Multistate foodborne outbreaks. Available at: www.cdc.gov/outbreaknet/outbreaks.html. Accessed Dec. 15, 2011.
• CDC. PulseNet. Available at: www.cdc.gov/pulsenet. Accessed Dec. 15, 2011. .

Disclosures: Drs. DuPont, Frieden, Gensheimer, Keene, Taylor and Williams report no relevant financial disclosures.

Are existing hazard analysis and critical control point (HACCP) programs adequate to maintain a safe food supply?

A properly used HACCP program can maintain a safe food supply.

Since its voluntary development by the food processing industry, beginning with Pillsbury in 1972, HACCP has proven to be an effective system of food safety management, a fact that was validated with its publication in 1992 by Codex Alimentarius, the commission created in 1963 to develop food standards, guidelines and related texts. HACCP works well because it identifies critical control points (CCP) that eliminate or minimize biological, chemical and physical foodborne hazards. In the case of biological hazards, examples of CCPs are the pasteurization of dairy products, the sterilization of canned foods and the acidification, freezing or drying of other foods. All of these can be definitive kill steps or control measures.

Continued food safety failures have led to criticism of the effectiveness of HACCP. Such criticism is mostly unwarranted, as many failures can be traced to faulty prerequisite programs and to counterproductive rules. We learned in the 1970s that HACCP is not synonymous with food safety. Many failures then were traced to inadequate cleaning and sanitation procedures and inadequate sanitary design of equipment, not to inadequate CCPs. It is now generally agreed that a food safety program must include a HACCP system that is supported by prerequisite programs — good agricultural practices (GAP), good manufacturing practices (GMP) and good consumer practices (GCP) — covering the entire farm-to-table supply chain.

Additional criticism of HACCP emerged following the recent publication of government rules that attempt to apply HACCP in food processing operations (such as raw meat and produce) that do not have definitive kill steps or control measures as described above. Rather, traditional CCP and GMP measures were recast as “partial CCPs” (author’s term). Predictably, these often fail. HACCP systems cannot be blamed for the resulting adverse public health outcomes related to such rules, which also create the false expectation that foods typically consumed raw or undercooked will be pathogen-free when distributed to consumers.

We need much better food safety education and communication. All parties involved in the supply chain must recognize that food safety is best assured by a HACCP system that is supported by GAPs, GMPs and GCPs; and that everyone has a role in food safety. Such a program remains our best means to maintain a safe food supply.

William H. Sperber, PhD, is global ambassador for food protection at Cargill Corporate Food Safety and Regulatory Affairs. Disclosure: Dr. Sperber has been a food safety leader in the global food industry, working with Best Foods, Pillsbury and Cargill, and many association and government committees.

Many HACCP programs are not adequate to maintain a safe food supply.

HACCP plans throughout the food industry vary in the degree of safety they provide to foods. Such differences are largely due to the interpretation of the types of CCPs that may be applied. The original intention of an HACCP system was to apply CCPs that would eliminate the hazard. For example, for a microbiological hazard such as Salmonella, an effective CCP would kill at least 100-fold more of the harmful microorganism than would likely be present. This provides an extra margin of safety. The pasteurization treatment applied to fruit juices, for example, would kill at least 100,000 Salmonella or E. coli O157:H7.

The USDA-FSIS, as part of its Pathogen Reduction and HACCP “Mega-Reg,” which was adopted in 1996, required that meat and poultry processors develop HACCP plans and apply them to their operations. For products that are sold fresh, other than applying irradiation, which consumers have not generally accepted, there is no kill step available that after treatment would retain the fresh-like characteristics of meat and poultry. Hence, to comply with the Mega Reg, the term CCP was modified to controlling hazards rather than eliminating them. Therefore, a control measure such as refrigeration at 4·C (40·F) to prevent pathogen growth could be considered a CCP. Such CCPs enhance the safety of fresh meats and poultry but do not ensure safety as would a pasteurization treatment that would eliminate the pathogens.

In addition to differences regarding the elimination or control of hazards by a HACCP plan, a preponderance of the CCPs described by food processors in their HACCP plans are not validated for their processes. Hence, the CCPs that are applied in practice may not be fully effective in mitigating the identified hazard(s).

Finally, even the best HACCP food safety plan that has been fully validated and reliable will only be effective if it is properly implemented. There can be varying degrees of implementation of a company’s HACCP plans, in part reflective of a processor’s commitment to producing safe foods.

Michael P. Doyle, PhD, is regents professor and director at the Center for Food Safety at the University of Georgia. Disclosure: Dr. Doyle reports no relevant financial disclosures.

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