Disease Detectives Report on Progress in Fighting Foodborne Sickness

Federal disease detectives say they've seen a significant decline in rates of E. coli infections because of accelerated testing of the meat supply, but they're making slow progress against contamination by drug-resistant strains of salmonella.

Robert Tauxe, chief of the foodborne-disease unit at the U.S. Centers for Disease Control and Prevention, said he's also concerned by increasing rates of contamination of shellfish _ mainly raw oysters _ from a bacterium called vibrio that can be lethal to people with chronic liver problems.

"There's been some real progress in the prevention of (food) pathogens," Tauxe told the annual convention of the Institute of Food Technologists here this week.

But he reported that disease detectives "are finding more salmonella than we should," and that more needs to be done in the meat-and-produce industry to combat the pathogen.

The CDC last year detected salmonella infections at the rate of 14.7 cases per 100,000 people _ more than double the government's "healthy people" goal. There were similarly high rates of salmonella infections from 2000 to 2003.

Tauxe said the industry is responding to the problem, and he noted that this year, California's Almond Board is requiring that all nuts harvested be pasteurized after sporadic cases of salmonella were traced to raw almonds. Some 95 percent of the almond crop was already being treated through roasting or heating to kill the pathogen.

Tauxe said CDC disease detectives are also improving their ability to use genetic fingerprints to track the source of outbreaks.

He said fingerprinting was responsible for last year's breakthrough that allowed the CDC to match several outbreaks at Mexican and Italian restaurants in Pennsylvania to Roma tomatoes shipped from a Florida distributor. He recalled that CDC detectives looked at a similar salmonella outbreak in Indiana in 1992, but couldn't identify the food responsible.

How the Roma tomatoes became infected remains a mystery, Tauxe said. "It's an open question how they got contaminated."

Although salmonella is commonly associated with ground beef and poultry, there have been outbreaks traced to green onions and cantaloupe imported from Mexico, snow peas from Guatemala and alfalfa from Australia. About 6 percent of foodborne illness is associated with fresh produce, the CDC estimates.

Tauxe said government surveillance data shows that the meat industry has made improvements in averting outbreaks of E. coli O157:H7, a particularly virulent strain of the common pathogen that can attack the kidneys of young children and has killed some.

Following a number of E. coli outbreaks in 2001 and 2002, the meat industry installed new steam-cleaning machines for cattle carcasses and adopted more rigorous testing regimes at processing plants looking for the strain. Tauxe said the incidence of the pathogen last year was below the government's 2010 goal of one case per 100,000 population.

Jim Hodges, president of the American Meat Institute Foundation, said that there has been a decline of salmonella in ground beef, but that contamination in poultry remains a problem.

The U.S. poultry industry produces about 9 billion birds a year, mainly chicken. U.S. Agriculture Department statistics indicate that about 12 percent of chickens were positive for salmonella in 2001, 11 percent in 2002, and 13 percent in 2003.

Hodges said chicken producers know they have a problem with the pathogen and are trying out new technologies, including a possible vaccine, to reduce salmonella contamination. "There's increasing attention to salmonella," he said. "We're further along with this than we were years back."

Researchers say one reason why outbreaks of food poisoning continue to be a problem is that people aren't heeding government warnings.

"The older you get, the less likely you are to think foodborne illnesses common," said Toby Ten Eyck, a sociologist at Michigan State University. "People think, 'I've eaten a lot of meals and I'm OK.' "

Joyce Gordon, a Kansas State University professor who conducted a national survey for the Agriculture Department, found that many of those most vulnerable to the effects of foodborne pathogens _ the young, old, pregnant women and those with compromised immune systems _ weren't aware of government food-safety warnings, such as avoiding alfalfa sprouts or heating deli meats before eating them.

"People just don't know these recommendations exist," she said.