[Pathogen Protection] <em>Salmonella</em>: The Pervasive Pathogen

Cereal. Peanut butter. Cantaloupe.

Raw eggs and under-cooked chicken have long been associated with food-borne outbreaks of Salmonella. But increased consumer awareness, proactive food safety practices by processors and food service providers, and tightened regulations have had an impact. However, as recent recalls and the 2008 FoodNet report from the Centers for Disease Control and Prevention (CDC) show, Salmonella is of heightened concern, with recalls occurring for products not previously associated with the bacterium. The report cites incident rates twice the national health objective of 6.8 and notes Salmonella reduction as the greatest area for intervention.

Utilizing CDC assumptions and a per-year estimate of 1.3 million cases of Salmonella poisoning from all food-borne sources, an online USDA Economic Research Service calculator estimates that the annual economic cost of salmonellosis, including medical costs due to illness, the cost of time lost from work due to nonfatal illness and the cost of premature death to be $2.4 billion (in 2006 dollars).

INCREASING REGULATORY ACTION. In March, USDA’s Food Safety and Inspection Service (FSIS) began posting on its Web site the test results of individual broiler plants that are not in the best performing category for Salmonella control. This is part of USDA’s Salmonella Initiative Program (SIP), an 11-point, risk-based strategy for Salmonella reduction in raw products announced in 2006. Since then, the percentage of plants placed in the best-performing category more than doubled from 35 percent to 74 percent.

“What (SIP) does is really focus people’s attention on changing the testing and reporting on these types of diseases,” said Stanley Maloy, dean of the College of Sciences at San Diego State University and associate director of the Center for Microbial Sciences. USDA previously implemented similar programs for E. coli, which are helping decrease incidents, “so this should work with Salmonella too.”

The major differences between the two, Maloy explained, are that Salmonella is more pervasive but less serious an illness (for most) while E. coli is less pervasive but more serious. “I think this will be harder to manage, but it seems that (SIP) will have a positive effect.”

FDA has undergone a great deal of criticism recently for inadequate funding and resources, most recently on a Trust for America’s Health (TFAH) teleconference. During the call, Michael Taylor, a former FDA deputy commissioner for policy, FSIS administrator and professor at George Washington University, cited obsolete statutes impeding FDA’s abilities and the fragmented organizational structure of the various agencies responsible for various aspects of food safety, without a single point of leadership. “We haven’t given them the tools to do the job they are expected to do,” Taylor said. As a result, the agency focuses on the issue of the day and reacts to problems instead of addressing the symptoms, he said.

FDA has, however, begun making strides toward proactive prevention and is gradually gaining resources, with the incorporation of the 2007 Food Protection Plan and a recently announced hiring initiative that calls for 1,300 positions to be filled domestically and abroad to implement the new plan as well as the FDA Amendments Act of 2007 and the Import Safety Action Plan.

REALISTIC GOALS. While efforts from the various segments of the industry will certainly have an impact on food safety in general and food-borne illness in particular, it would be unrealistic to ever expect total elimination of the pathogens, said Maloy, who co-runs www.salmonella.org. “I think we’re never going to have 100 percent. That’s just not possible. It’s not realistic because these things can come from so many sources and you can’t test every single thing.”

In fact, it can be very difficult to detect Salmonella in other products, such as melons. “Very often, these are imported so you don’t have good control over their growing conditions,” he said. “And if it is inside the product, you may not be able to detect it.”

These products also can prove to be difficult to test, because an early test can indicate low or no Salmonella levels, but the pathogen’s numbers can grow during shipment. Domestic produce certainly can have the same issues, he said, “but with the U.S., you have a little more control over the growing conditions.”

A second issue then lies with the changing distribution of fresh produce. With processors answering consumers’ call for ready-to-eat products, the cut pieces of a few infected melons can contaminate an entire batch, increasing the probability of exposure to greater numbers of consumers.

IN-PLANT PREVENTION. With Salmonella a growing concern, processors should take a fresh look at their food safety processes and practices toward prevention of this pervasive pathogen. One of the best Salmonella controls is the maintenance of proper temperatures. “It grows best when things warm up; if you keep things cool, you keep (Salmonella) from growing effectively.” On the other hand, Maloy said, Salmonella is readily killed by heat. It is for this same reason that ready-to-eat items such as melon and peanut butter, as well as under-cooked chicken or raw eggs, have greater potential of causing food-borne illness.

“At the vegetable and fruit level, the best thing you can do is have good testing,” Maloy said, especially at both the point of receipt in the U.S. and at customer delivery.

Maloy said better, faster and cheaper tests would benefit the industry greatly. If FDA had more funding, it could really push these things, Maloy said. As it is, development will most likely require a push from industry. “One of the biggest things that the food manufacturers need to do is to keep pressure on the federal government, so they do not neglect these things in favor of things that get more play — like bioterrorism.”

PUBLIC AWARENESS. More media attention can increase public awareness and identification of illness cases. But Maloy does not believe this is the only reason for increased incidents. “It may be true that we are becoming more aware, but it also may be true that we are providing more ecological niches for Salmonella to grow,” Maloy said. Farm practices should be investigated and continually monitored, and plants should ensure they can trace the food safety practices on all incoming goods.

Maloy said that food-borne illness is nothing new, but has been around throughout humankind and goes through phases of activity and media attention. “Salmonella does go through periods in which we seem to see greater incidence of it, then more of it in the news,” he said. In addition, for the general consumer, the food-borne illness is just that — an illness. “If you are not very young, very old or immuno-compromised, you are probably going to get Salmonella and be sick for a couple days, then you’ll get over it.”

A PERVASIVE PATHOGEN. Maloy cited two examples to depict Salmonella’s pervasive nature: Many people think that free-range chicken is a healthy alternative, but these chickens are, in fact, exposed to Salmonella by flying migratory birds and rodents living nearby, he said. In a global example, he added, England has a number of old-fashioned chicken houses, through which Salmonella is very easily spread by field mice coming in to the houses attracted by the chicken feed.

Maloy said that while better and faster tests, as well as food safety initiatives to detect and contain the bacteria, are important, a vaccine could be a more effective way to handle salmonellosis. “It is so pervasive, it virtually can be spread by anything walking or crawling or flying.” So rather than trying to deal with it in nature, he said, “I think something that would be very reasonable for us would be if we had a broad vaccine against this variety of disease.”

The author is Staff Editor of QA magazine.