Salad greens make the most people sick, but contaminated poultry kills the most Americans, federal researchers report in the first comprehensive look at the foods that cause foodborne illnesses. And there are a few surprises -- the bug most likely to be lurking in a salad is norovirus, and it probably came from the hands of the person who made it.
This doesn’t mean salad is more dangerous, the team at the Centers for Disease Control and Prevention stresses: It just shows what foods are most involved and may reflect how often people eat them.
“When the average American looks at this data, they need to know that we are not trying to make estimates of the risk of illness per serving of any of the food categories,” says the CDC’s Dr. Patricia Griffin, who heads the agency’s branch that investigates stomach bugs.
“We are just providing information on what are the food categories that are the major sources of illness ... so regulators can take action to make food safer.”
Food poisoning is extremely common. The CDC estimates that 48 million Americans get some sort of foodborne illness every year, 128,000 of them are sick enough to go to the hospital and 3,000 die. Most of the time, the bacteria, virus or parasite responsible is never identified, and usually the particular food isn’t, either.
Griffin’s team analyzed all the data they could get on every outbreak of foodborne illness reported between 1998 and 2008 in which both the food source and the microbe responsible were known. They broke the food down into 17 categories.
“We attributed 46 percent of illnesses to produce and found that more deaths were attributed to poultry than to any other commodity,” they wrote in their report, published in the journal Emerging Infectious Diseases on Tuesday.
“(The data ) indicate that efforts are particularly needed to prevent contamination of produce and poultry.”
This doesn't mean people should swap out salads for, say, fries.
“We certainly would not want people to avoid any category of food,” Griffin said. “We know that the vast majority of meals are safe. As far as fruits and vegetables in particular, CDC is well aware and promotes the fact that they are an important part of a healthy diet. They are linked to reduced risk of heart attacks, strokes and cancer. “
Cooking food is one of the best ways to prevent illness, as proper cooking will kill most disease-causing agents. As raw meat and eggs are often contaminated, proper food handling techniques are also important.
It’s harder to protect against germs on raw food, however. “Our data found that produce items were a common cause of illness, accounting for almost half of illnesses,” Griffin said in a telephone interview. “Most of those produce items that caused those illnesses were consumed raw.”
And norovirus – also known as Norwalk virus, which causes gastrointestinal upset commonly known as stomach flu or winter vomiting disease – was a major cause of illness contracted from raw vegetables, the CDC finds.
Contaminated meat and poultry accounted for 22 percent of illness but 29 percent of deaths, while dairy and eggs accounted for 20 percent of illnesses and 15 percent of deaths.
Last week, CDC reported 1,527 foodborne disease outbreaks in 2009 and 2010. They said 29,444 people got sick and 23 died in these outbreaks. Norovirus or Salmonella -- especially in eggs, sprouts, tomatoes and peppers -- caused most, while Campylobacter in unpasteurized dairy products, Salmonella in eggs, and E. coli 0157 in beef were also very common causes of food poisoning outbreaks. And nearly half -- 48 percent -- of all outbreaks from a single place were traced to restaurants or delis.
News reports have focused a great deal on outbreaks of diseases such as salmonella, listeria and E. coli, and the Food and Drug Administration, US Department of Agriculture and other regulators have focused on protecting food from animal contamination such as bird droppings and manure from pigs and cows, which carry these agents.
But norovirus is carried and spread only by humans.
“The way that you get it from food is when a food handler doesn’t wash his hands after an episode of diarrhea or vomiting and then prepares food,” Griffin said. This is an area that may require extra focus, she says.
“Washing hands is very, very important,” she added. Norovirus can be spread before a person feels sick and for days after he or she recovers, also.
Adding to the risk is the issue of sick leave. Many food preparers, restaurant workers and food handlers do not get paid sick leave, and thus are encouraged to work while they are ill. One study published in 2011 in the American Journal of Public Health projected that workers who did not get paid time off for illness helped spread 5 million cases of respiratory disease during the 2009 H1N1 swine flu pandemic.
The Bureau of Labor Statistics says 39 percent of private sector workers have no paid sick leave, and this number rises to 70 percent for food and hotel workers.
There’s a bill in Congress that would mandate sick leave for many employers, supported by President Barack Obama and groups including the National Women’s Health Network, the AFL-CIO, Families USA and others. It was last considered in 2009.
So besides cooking meat and making sure greens are washed well, how can people protect themselves? “I would advise people to avoid eating raw foods of animal origin, and that includes raw milk,” Griffin said. Shellfish? “You have to make a decision about raw shellfish and how much you love them, how much risk you want to take and what your risk might be,” she said.