A looming threat
Aug. 8, 2011
Although the US food industry’s war against foodborne pathogens rages on, industry has been winning more battles, particularly in recent years. Illnesses caused by pathogens such as E. coli
O157 have declined nearly 50 percent during the past 15 years, and the overall rates of six foodborne infections have been reduced by 23 percent – so claims “Vital Signs,” a study recently issued by the Centers for Disease Control and Prevention, based in Atlanta. But during that same time frame, Salmonella
infections increased 10 percent.
CDC’s Vital Signs report summarizes 2010 data from the CDC’s Foodborne Diseases Active Surveillance Network (FoodNet). In 2010, FoodNet sites, which include about 15 percent of the American population, reported nearly 20,000 illnesses, 4,200 hospitalizations and 68 deaths from nine foodborne infections. Of those, Salmonella
caused more than 8,200 infections, nearly 2,300 hospitalizations and 29 deaths (54 percent of the total hospitalizations and 43 percent of the total deaths reported through FoodNet). CDC estimates 29 infections for every lab-confirmed Salmonella
The rate of E. coli
O157 cases reported by FoodNet sites was two cases per 100,000 people in 1997 and by 2010 had decreased to 0.9 cases per 100,000 people. The nearly 50-percent reduction in E. coli
O157 incidence is significant when compared to the lack of change in Salmonella incidence.
“Although foodborne infections have decreased by nearly one-fourth in the past 15 years, more than 1 million people in this country become ill from Salmonella
each year, and Salmonella
accounts for about half of the hospitalizations and deaths among the nine foodborne illnesses CDC tracks through FoodNet,” said Thomas Frieden, CDC director. Keep it in perspective
cases CDC refers to did not involve red meat or poultry. Major US Salmonella
outbreaks that occurred in recent years, such as the peanut butter outbreak in 2009 and the egg and alfalfa sprouts outbreaks in 2010, involved products under FDA’s jurisdiction, says Shelly McKee, Ph.D., associate professor of poultry science at Auburn Univ.
Since January 2010, the Food Safety and Inspection Service has posted five Salmonella
-related recalls of US Dept. of Agriculture-regulated products on its website – vs. 15 Salmonella
-related recalls posted on the Food and Drug Administration’s website, involving grape tomatoes, alfalfa sprouts, cilantro and whole cucumbers, among other products.
Poultry products appearing to be ready-to-eat but aren’t, such as some Chicken Cordon Bleu products, are now under closer FSIS scrutiny because some people want to microwave these products, McKee says. “If such a product contains Salmonella, microwaving doesn’t necessarily kill it because consumers are not actually cooking it properly,” she adds. “If one more outbreak occurs [regarding such products], FSIS is going to come down hard on that segment.”
The latest CDC news on Salmonella
is not necessarily a negative reflection on the US meat and poultry industry, agrees Mindy Brashears, professor and director of the International Center for Food Industry Excellence at Texas Tech Univ.
“Texas Tech Univ. recently completed a nationwide survey of ground and whole-muscle beef products in 28 states in 32 cities in the US,” she says. “The overall Salmonella
prevalence was 0.65 percent. It is also important to note USDA-FSIS data reported in the first quarter of 2011 indicated that of the samples tested of steer/heifer, cow/bulls and ground beef, only 0.4 percent, 0.9 percent and 1.3 percent tested positive, respectively.
“A total of 6.7 percent of broilers and 3.2 percent of turkeys were positive,” she adds. “Ground poultry products may be an area where more work is needed with ground turkey testing positive in 10.7 percent of samples and ground chicken testing positive in 35.6 percent of samples.”
Unlike some foodborne pathogens, such as E. coli
O157:H7 which is considered to have a reservoir primarily in cattle, Salmonella is ubiquitous in the environment, Brashears explains. “It survives and adapts well to many foods and in many environmental areas,” she adds. “Humans can even become carriers of this pathogen. In order to control this pathogen, our thinking cannot be limited to controlling it in meat and poultry alone. The attack must be more widespread.”
CDC’s estimates show there has been very little change in the prevalence of Salmonella
-caused illness in humans in the last 15 years, says Scott Russell, Ph.D., a microbiologist and professor of poultry processing at the Univ. of Georgia and science advisor to the National Chicken Council. “Yet, we know the presence of Salmonella
on raw chicken meat has declined sharply in the last 15 years,” he added. “Chicken companies have done a very good job improving the microbiological profile of raw products, and consumers should continue to practice common-sense safe handling and preparation steps. To further reduce human exposure to Salmonella
, other sources should be examined more closely.”
Starting in July, FSIS is implementing revised and new performance standards aimed to further reduce the prevalence of Salmonella
in young chickens and turkeys. After two years of enforcing the new standards, FSIS estimates almost 5,000 illnesses will be prevented each year under the new Campylobacter
standards, and approximately 20,000 illnesses will be prevented under the revised Salmonella
standards per year.
“Industry is doing a good job. [USDA] is taking extra care in the new performance standards to tighten up the guidelines,” Auburn’s McKee says.
Stricter performance standards were developed by FSIS using recently completed nationwide studies measuring the baseline prevalence of Salmonella
in young chickens and turkeys prepared for market. Despite improvements, there was still a risk of consumers being exposed to these pathogens through poultry, the studies indicated.
Since the 1990s, USDA has monitored chicken and turkey plants for Salmonella
. For the third quarter of 2010, an average of 7.4 percent of chicken carcasses at processing plants nationwide tested positive for detectable levels of Salmonella. The actual experience in processing plants is believed to be somewhat lower since the government tends to conduct more sampling in plants with higher Salmonella
results, according to NCC. The new USDA performance standard is 7.5 percent.
The new Campylobacter
standard requires that no more than 10.4 percent of raw chickens sampled should have Campylobacter
jejuni, C. lari
and/or C. coli
on them. Samples will be taken at the same time as the Salmonella
samples are collected, NCC stated. Moving forward
The US poultry breeding industry does an excellent job vaccinating flocks and with biosecurity, McKee says. “But once we get to the hatchery and those chicks go to growout, we start to lose that strong control. That’s where we have opportunities in technologies and antimicrobials that can be cost-effective but also effective.”
The entire system from production to consumer plays a role in decreasing Salmonella and preventing illnesses, Brashears says.
“We must attack pathogens from several angles,” she adds. “Reducing the pathogen loads in the animals before they enter the harvest facilities is critical. The animal is the primary source of the pathogen that contaminates the final products. Using pre-harvest interventions and establishing a baseline of good production practices can help control the pathogen loads coming into a facility.
“We must implement good dressing procedures to prevent contamination and implement interventions to reduce pathogen loads on products,” she says. “It is also important to consider contamination may not be coming from our ‘traditional’ sources, such as hides, and may be coming from other sources, such as lymph nodes.
“Finally, the consumer must be aware of this problem and handle the product correctly to prevent illnesses from occurring,” she concludes.