Salmonella Lurks From Farm to Fork
The rate of salmonella infections is rising, despite efforts to combat this leading cause of food illness.
In chicken houses longer than a football field, newborn chicks huddle together for warmth, forming a fuzzy, moving yellow carpet.
Over the next two months, these chicks will peck at the dirt, nibble on pellets, get packed into crates, be trucked to a slaughterhouse, get cut into parts and arrive at a distribution center for shipment to supermarkets and restaurants.
Government and industry readily expect that some of those chickens will arrive at their destinations contaminated with salmonella, a foodborne pathogen that can lead to salmonellosis — an infection in humans that causes diarrhea, fever and stomach cramps, and, in severe cases, can spread from the intestines to the bloodstream.
Despite measures taken to reduce salmonella from farm to fork, it’s a tough pathogen to eliminate. So consumers and food service handlers are told to cook poultry thoroughly and to avoid cross contamination.
That approach hasn’t worked.
Unlike other foodborne illnesses, not only has the rate of salmonella infections failed to decline in the last 15 years, it’s actually gone up recently by 10 percent, sickening more than a million Americans a year. The Centers for Disease Control and Prevention has called for strong and specific actions to address the problem.
Salmonella is found in a range of food products, including meat, produce and eggs. Chicken is the single biggest source of infection among cases where a food has been identified, causing about 220,000 illnesses, 4,000 hospital stays and at least 80 deaths annually in the U.S., according to an analysis of CDC data by the Emerging Pathogens Institute at the University of Florida.
But gaps in government oversight — including meaningful testing and enforcement — along with inconsistent practices among farms and processing plants and varying levels of industry commitment to spend money on the problem have all led to a fractured effort, leaving the ultimate responsibility for food safety with the consumer.
Salmonella jumps from one link in the chicken chain to the next, with multiple openings for contamination along the way.
Food safety experts and poultry scientists say that salmonella control has to start on the farm, but federal food safety inspectors never set foot there. The Agriculture Department’s Food Safety and Inspection Service lacks the legal authority to test for salmonella on farms or to require farmers to have a food safety plan.
As a result, measures to prevent salmonella are implemented voluntarily by farmers or because poultry processing companies ask them to — a situation that leads to a patchwork of efforts, some of which work better than others.
For instance, vaccinating the hens used in breeding can reduce the incidence of salmonella in their offspring. Researchers at the University of Georgia in a study published last year found that 20 percent of chicks hatched from vaccinated breeders tested positive for salmonella before slaughter, compared with 30 percent of chicks from unvaccinated hens. And research published this year by the same group found that if a vaccinated chicken is contaminated with salmonella, it will have, on average, 50 percent fewer cells of the bacteria than an unvaccinated bird.
The cost of the vaccines, including administering them, runs about 38 cents per bird for Perdue Farms, according to company spokeswoman Julie DeYoung.
While vaccination has been on the rise over the last two years, the practice has not been widely embraced by the poultry industry as a whole. Among those breeding operations that do vaccinate their birds, the number of doses given and the strains of salmonella that are targeted vary widely. This can impact the vaccines’ effectiveness in keeping salmonella out of flocks.
From the hatchery, baby chicks are trucked by the thousands in huge tractor-trailers to independently owned chicken houses that raise the birds under contract with poultry companies.
At one such operation, Mike Weaver’s poultry farm in Fort Seybert, W.Va., pallets containing about 10,000 chicks each are dumped on the floor of the houses, where workers direct the birds toward the feed trays and water lines. Outside the chicken houses are T-shaped PVC traps to catch rats and other rodents.
Properly chlorinated water, pest control, sanitation and biosecurity are crucial for controlling salmonellosis (as well as other diseases). The government requires none of these measures, so farmers follow a variety of practices, some of which are mandated by companies but may not be scientifically monitored.
Weaver raises birds for Pilgrim’s Corp., the country’s second-largest poultry processing company. Pilgrim’s supervisors visit his farm every week or two but do not test his water or birds.
In fact, live birds are almost never tested for salmonella. And the bacteria, which have no odor and cannot be seen by the naked eye, do not make the birds sick, so they show no signs of being infected.
With no test results, farmers don’t know whether their chicks have salmonella — and, if they do, how widespread the infection is — or whether their interventions have been effective. This moves the onus of killing the pathogen later down the line.
“When it goes down to the processing plant, it’s all cleaned anyway,” said Timothy Turner, who worked for Weaver.
This is a risky, often untrue premise.
“You don’t want every play to be goal-line defense,” said Joe Forsthoffer, spokesman for Perdue Farms Inc. “The less you bring into a plant, the better results you have.”
The birds’ trip to the plant in open-air trucks also leaves them vulnerable to infections. The dirty conditions in their tightly packed crates present opportunities for pathogens to spread, and contaminated feces from one flock can taint the next flock because the trucks are cleaned infrequently. Crates and trucks are not washed regularly between shipments because there is often not enough time to allow them to dry properly. Loading flocks into damp crates and trucks could make the situation worse, since bacteria thrive in moist environments.
Transport to the slaughterhouse can also weaken a chicken’s immune system, increasing salmonella levels in its gut. USDA researcher Marcos Rostagno noted that overcrowding, extreme temperatures, food and water deprivation, rough handling and even just the normal motions of a truck lumbering down a highway can produce stress, allowing salmonella to thrive.
And once salmonella bacteria enter a processing plant, poultry experts say, it’s difficult to get them out.
Strung up on racks like clothes at a dry cleaner, chicken carcasses whiz by — about 200 of them per minute — in the alternately steamy and uncomfortably cold Perdue plant in Georgetown, Del. About a million birds are slaughtered at the plant each week.
Fresh from having their throats slit, the birds snake along in lines, their bodies pale, limp and lanky. After a communal bath, they are de-feathered and strung back up for evisceration. Each chicken’s guts are mechanically removed and placed on a plate for the USDA inspectors to check for signs of disease that make the birds sick. Overhead, the corresponding carcasses are checked for visible fecal contamination, which can be a sign that salmonella is present. The government conducts microbiological sampling for salmonella only once a year in most plants.
After inspection, the birds get a chilly bath, bobbing and soaking for two hours to lower their body temperatures. Then the carcasses are disassembled — manually and by machine — into the pieces consumers will ultimately eat.
At every step along the way, there are opportunities for salmonella contamination to spread and opportunities to prevent it. USDA requires every processing plant to have a food safety plan — a list of points in the production process where dangers can arise and how the company plans to control them. But companies set their own strategies. It’s up to them to decide how thorough the interventions are, leading to variations in the level of pathogen control at different plants.
On its website, USDA lists the names and locations of slaughter plants where salmonella has been detected in more than 10 percent of the poultry tested by the agency. Since the end of 2007, the list has included nine of Tyson Foods’ 33 broiler plants and six of Pilgrim’s 26 plants that were operating as of August (but no Perdue plant currently in operation). Together, the country’s three largest poultry producers — Tyson is No. 1, Perdue No. 3 — account for about half of the 38 billion pounds of chicken produced in the U.S. each year.
In addition to its Georgetown processing plant, Perdue gave News 21 a tour of one of its hatcheries and a feed mill, along with a farm with which it has a contract. Companies generally own all aspects of poultry production with the exception of the farms.
At the Georgetown plant, brushes, treated water and antimicrobial rinses are constantly monitored throughout the line, and Perdue voluntarily tests birds for salmonella throughout the week at various stages of the process. Contamination can vary from flock to flock and season to season, said Bruce Stewart-Brown, the company’s vice president of food safety and quality.
The key to killing salmonella is being vigilant in maintaining proper temperature, pH level and chemical concentration of the water as well as keeping a close eye on other controls. For example, if the flow of fresh water in the scalder is not managed properly, each carcass will continually be rinsed by dirty water, exposing it to cross contamination.
“From what I saw, some [companies] work harder than others,” said Stan Bailey, a retired USDA microbiologist, who declined to name specific companies. “I think different people have different attitudes on how much they’re willing to spend.”
Companies that do not want to spend money on extra food safety precautions don’t have a big incentive to do so. No matter how much salmonella USDA finds in raw meat, it cannot be kept off the market.
That wasn’t always the case — or at least it wasn’t the intent.
In 1998, USDA, citing regulations allowing it to set enforceable performance standards, told meat and poultry processors they would be shut down if their salmonella contamination level exceeded 20 percent — then the industry’s average — for three consecutive tests. Production would halt. Money would be lost. And a plant would have to fix the problem before it could reopen.
A Texas-based meat company sued. The company, Supreme Beef Processors, Inc., said USDA had no legal authority to shut it down after it failed three salmonella tests over eight months.
The courts agreed. In 2001, a federal appeals court upheld a lower court’s decision accepting the company’s argument that, because salmonella is naturally occurring, the government cannot close a plant due to salmonella contamination.
Elsa Murano, USDA’s undersecretary for food safety at the time, told News21 that the agency still has the power to close plants for failing to follow their own food safety plans; and she said that salmonella testing is just one indicator the agency uses to measure companies’ performance.
Salmonella doesn’t pose a danger if chicken is thoroughly cooked, Murano noted. “Raw chicken can have bacteria on it. Cooked chicken better not.”
Efforts in Congress to give the performance standards teeth have stagnated.
Following the court decision in the Supreme Beef case, Sen. Tom Harkin, D-Iowa, introduced legislation to give USDA the legal authority to shut down plants that repeatedly violate performance standards. Senate Republicans voted as a bloc to kill it, joined by two Democrats who had received campaign donations from agribusiness in the previous election cycle. When Harkin, chairman of the Senate Agriculture Committee at the time, introduced a similar amendment a year later, it was derailed before reaching a vote.
Harkin then made repeated efforts to advance legislation known as “Kevin’s Law” — in memory of a Wisconsin toddler who died in 2001 after eating a hamburger contaminated with E. coli O157:H7 — but the measures never got out of committee. Similar bills on the House side sputtered as well.
Kevin’s mother, Barbara Kowalcyk, who became a food safety advocate after her son’s death, said a key to controlling salmonella and other pathogens is for government to have enforceable performance standards. If processing plants exceed agency-set limits, Kowalcyk wants USDA to have the power to shut them down.
Some of the ideas in Kevin’s Law were included in the Food Safety Modernization Act, signed into law in January. It gives inspectors from the Food and Drug Administration the authority to order recalls and shut down processors that repeatedly sell contaminated produce, eggs or other non-meat products. But the new law doesn’t apply to USDA and the meat processors it oversees.
Despite USDA’s lack of enforcement muscle, in July it tightened its performance standards for poultry slaughterhouses for the first time. Under the new standard, no more than 7.5 percent of a plant’s raw chickens can test positive for salmonella bacteria — down from 20 percent previously and in line with the industry’s recent average.
As an incentive to comply, plants that don’t meet USDA’s standards are posted online.
In general, the government tests processing plants for salmonella once a year — with a sample of 51 birds a year. Problem facilities are tested more often.
But the tests don’t accurately reflect the level of contamination when the chicken leaves the plant, said Robert Tauxe, deputy director of the Division of Foodborne, Waterborne and Environmental Diseases at the CDC.
Tauxe explained that the tests sample whole carcasses at the end of the slaughter line — after almost all of the steps to contain salmonella have been taken but before the birds are cut into pieces, when further cross contamination can happen.
This helps explain why the USDA’s salmonella contamination rate of 7.5 percent in slaughter plants is lower than what the FDA has found in retail stores. In 2009, FDA tests showed that 21 percent of the chicken breasts it sampled from grocery stores were contaminated with salmonella. (The FDA measures salmonella in USDA products for its research on antibiotic-resistant pathogens.) The 2009 finding, the most recent such study available, showed that contamination in chicken breasts had spiked sharply since 2007, to its highest level in seven years.
“The chickens walk into the slaughterhouse with salmonella on board and they leave with salmonella on board,” said Tauxe.
And it still has opportunities to spread.
On the loading dock of the Perdue plant in Delaware, packaged poultry is readied for shipment. The back of each truck is sealed with a plastic loop to prevent tampering. A guard wanders the lot every hour, checking the thermometers on the outside of each tractor-trailer to make sure that temperatures haven’t risen to dangerous levels.
Before a truck can leave the lot, a guard breaks its seal and inspects the shipment. The seal is then replaced. From now on, temperature control is the driver’s responsibility.
At this point, if salmonella is present it can no longer be reduced. Levels can remain the same, or they can increase.
Heat is the main danger.
When fresh poultry is not kept below 41 F, bacteria multiply. In just a few hours, a small concentration can expand into a thriving pathogenic colony.
Companies record the temperature of packaged meat as it enters and exits a refrigerated trailer. Some large retailers require suppliers to record in-transit temperatures, too. But most transporters don’t take these readings, so who’s to know if their meat got too warm inside the trailer?
A 2007 industry study found unsafe temperatures in 30 percent of food transports between processors and distribution centers and in 15 percent of food transports between distribution centers and retail stores.
Here again, the government isn’t really checking. Federal regulation of food transport has been shared and tossed around among various agencies over the last half century and hasn’t always taken food safety into account.
In 1957, Congress directed USDA to establish rules for storage and transport of poultry, but the final regulations were not issued until 1975 — and they didn’t address temperatures. In 2003, USDA issued voluntary guidelines for the transport of poultry — including recommended temperatures — but has taken no further action.
Meanwhile, the Department of Transportation was supposed to implement the 1990 Sanitary Food Transportation Act; but after a proposal that went nowhere, the department determined in 1998 that it lacked the expertise to do so. In 2005, Congress transferred responsibility for regulating food transport to the FDA, which is still trudging through the rule-making process.
“There’s probably less attention paid to transportation than there should be,” said Sarah Klein, staff attorney at the Center for Science in the Public Interest, a consumer advocacy group. The regulation of food transportation, she said, is “a little bit of a no man’s land.”
At a Giant Food store in Baltimore, Shemaiah Miller pulled an anti-bacterial wipe from a dispenser and swiped the handle and inside of her shopping cart, hoping it would take care of any invisible pathogens from any raw chicken or hamburger that occupied the cart before her lettuce.
“I just like to think I’m wiping it away,” she said.
Her gesture drives home the point: Whatever salmonella has accumulated on food during its journey from the farm ends up in the hands of consumers, whether they expect it or not. And it’s up to them to know how to kill it (during cooking) and prevent cross contamination during preparation.
To reduce the risk from salmonella, USDA says poultry should be cooked to 165 F, as measured by a meat thermometer. To prevent cross contamination during food preparation, people should wash their hands with soap and warm water for 20 seconds before and after handling raw poultry or other foods; and they should wash cutting boards, utensils and countertops with hot, soapy water or a bleach solution after cutting raw poultry or other meats.
Although USDA has spent millions of dollars to educate the public about food safety, studies indicate that consumers don’t always know, or practice, the techniques recommended by government and industry.
Half of American consumers do not use food thermometers, 40 percent don’t separate raw from ready-to-eat foods, and almost half use the same cutting boards for raw poultry and produce, according to a 2011 survey by the International Food Information Council Foundation, a public education group based in Washington.
The survey also found that only 39 percent of Americans accept some responsibility for food safety; 71 percent said it’s the government’s job, and 67 percent said food manufacturers should share in the responsibility.
“Food that comes into your home contaminated — not your fault,” said Klein, the CSPI attorney. “The food shouldn’t have been contaminated in the first place.”
News21 reporter Robyne McCullough contributed to this article.