The conference included a presentation on beef-related illness data by L. Hannah Gould, Ph.D., leader of the National Outbreak Reporting System Team at the U.S. Centers for Disease Control and Prevention (CDC).
Despite the two decades of progress made to reduce beef-related outbreaks, beef is still the third most common food commodity to be associated with illness, just behind fish and dairy, Gould said.
Anywhere from 11 to 28 percent of the U.S. population is estimated to consume ground beef raw or uncooked, Gould said. And, with 25 billion pounds of beef consumed in the U.S. each year, there is ample opportunity for foodborne illness.
CDC counted at least 75 outbreaks associated with beef over the five-year period between 2009 and 2013. Of those, 35 percent were caused by E. coli O157:H7 and 23 percent by Salmonella, leading Gould to focus on both of those pathogens in her presentation.
The presentation was split into two parts based on two separate papers CDC plans to publish in the coming months. The first is a 10-year update to CDC’s previous 10-year summary of E. coli outbreaks, while the other summarizes a history of Salmonella outbreaks caused by beef dating back to 1973.
Because neither paper has been released yet, Gould told Food Safety News that the data reported in the presentation should be considered preliminary and unpublished.
E. coli O157:H7, the pathogen most commonly associated with ground beef, causes an estimated 96,000 illnesses, 3,200 hospitalizations and 31 deaths in the U.S. each year, adding up to $405 million in annual healthcare expenses.
CDC tracked 391 E. coli O157:H7 outbreaks in the 10 years between 2003 and 2012. Between those outbreaks, the agency confirmed 4,930 cases of illness, with 1,274 (26 percent) hospitalizations, 300 (6 percent) cases of hemolytic uremic syndrome (HUS), and 34 deaths.
Food is by far the most common source of E. coli O157:H7, accounting for 65 percent of cases. The other major sources of E. coli are animal contact (10 percent) and person-to-person transmission (10 percent).
The most common food source for E. coli turns out to be beef, which has been implicated in 55 percent of E. coli outbreaks. The next closest commodities are leafy greens (21 percent) and dairy (11 percent). All other meats and poultry together account for 6 percent.
Breaking those beef sources down even further reveals that ground beef causes 69 percent of related outbreaks, while steak is linked to 14 percent and “other” beef to 17 percent.
E. coli outbreaks tend to peak in July each year, which matches up perfectly with the time of year that cattle shed the most E. coli.
Beef was also found to be much more likely to sicken people who cooked it at home compared to eating out. According to the data, private home cooking accounted for 33 percent of all E. coli O157:H7 outbreaks, but it accounted for 56 percent of all beef-related E. coli outbreaks.
The major takeaway, Gould said, is that beef is still the most common source of E. coli, and young children are the most impacted age group. CDC also tracked more E. coli outbreaks from 2003-2012 than in the previous 20 years.
Despite serious efforts to control Salmonella, rates of Salmonella infection have remained steady for the past 15 years. And, in recent years, industry has taken a heightened interest in finding ways to reduce Salmonella contamination in beef.
According to CDC, beef is the fourth most common cause of Salmonella outbreaks. Salmonella, however, is not considered an adulterant in beef the way several strains of E. coli are considered adulterants in ground beef.
CDC tracked at least 95 outbreaks of Salmonella from beef between 1973 and 2011, resulting in 3,643 confirmed illnesses and 318 (9 percent) hospitalizations.
While roast beef seemed to be the predominant cause of beef-related Salmonella outbreaks in the 1970s and 1980s, ground beef has become the dominant source since 1990, and the data show a sharp increase in ground beef-related Salmonella outbreaks after 2000.
With antimicrobial resistance data available in 14 outbreaks, isolates from eight of those outbreaks (57 percent) were found to be resistant to at least one class of antimicrobial agent. Ground beef was the food source in all eight of those outbreaks.
Those antimicrobial-resistant Salmonella outbreaks were also found to be more virulent: While 9 percent of patients were hospitalized in outbreaks involving strains with no resistance, antimicrobial-resistant strains hospitalized 23 percent of patients.
The takeaway here, Gould said, is that outbreaks of antibiotic-resistant Salmonella in ground beef appear to be a growing problem.
“More needs to be done with Salmonella and beef,” she said.
Avoiding outbreaks caused by beef
Gould ended her presentation with some recommendations for reducing the number of foodborne illness outbreaks caused by beef. Namely, she said, consumers and food handlers need to be educated on the dangers of undercooked beef, including mechanically tenderized steak.
She also called for more judicious use of antibiotics in human medicine and animal husbandry, as well as tighter controls to prevent the contamination of antibiotic-resistant Salmonella in ground beef.
Gould added that she values the opportunity to share these data with the beef industry.
“Any time we have a chance to collaborate with industry is great,” Gould told Food Safety News. “There’s a shared desire to not have illnesses and outbreaks associated with beef and other meat products