From farm to table, is our food safe?

Estimating the National Burden of Foodborne Illness

It’s been in the peanut butter we spread on our crackers, the spinach that forms our healthy salads, and the hamburger we use at our all-American barbeques.  In the past year, foodborne diseases have been transmitted through the foods we least expect; yet we often don’t know how many people have been affected.

In 1999, the Centers for Disease Control and Prevention (CDC) estimated that foodborne diseases cause approximately 76 million illnesses and 5,000 deaths in the United States each year. With more than 200 known diseases transmitted through food, many cases go undetected. However, Dr. Elaine Scallan, assistant professor in the Department of Epidemiology at the Colorado School of Public Health is working to change underreporting and update the 1999 CDC numbers.

“We can do more to say certain foods are risky by estimating the burden of disease and then connecting that burden to certain food products,” says Dr. Scallan.

Working with the Foodborne Diseases Active Surveillance Network (FoodNet) a CDC Emerging Infections Program and the Colorado Department of Public Health and Environment (CDPHE), Dr. Scallan is researching the national burden of foodborne diseases, a task she’s been at for more than six years.  “Once we determine the number of illnesses, we will able to go back and look at the causes of those illnesses,” Dr. Scallan says.

Started in 1996, FoodNet provides accurate estimates of foodborne illness in the U.S. through laboratory-based active surveillance and epidemiologic studies. Today, FoodNet collects data on seven bacteria, two parasitic organisms and one syndrome that cause foodborne illness from only 10 U.S. states, including Colorado.

“It is a real honor to be chosen as a FoodNet site,” says Alicia Cronquist, foodborne and enteric disease epidemiologist in the Communicable Disease Epidemiology program at CDPHE. “FoodNet allows us to enhance our routine surveillance activities for enteric illness in the Denver metro area and gives us the opportunity to participate in special research studies.”

Utilizing surveillance data from FoodNet and PulseNet along with physician, laboratory and community surveys, Dr. Scallan is calculating the national incidence of the nine key pathogens. Although foodborne illnesses can be severe or even fatal, milder cases are often not detected.  According to Dr. Scallan, most foodborne infections are sporadic, that is, they occur as individual cases that are not part of recognized outbreaks.

“It’s important to recognize the number of cases reported and the number of cases in the community is going to be very different,” states Dr. Scallan. “We’re giving our best guess on estimating the burden.”

To fully understand underreporting, Dr. Scallan is compiling information from several population groups. The first group is laboratories.  She says not all laboratories test for all foodborne pathogens, resulting in fewer laboratory-confirmed infections. Second, she says physicians have to know what they want laboratories to test for. If they don’t know what to test for, it is really hard to diagnose foodborne illnesses. Third, she says she needs to understand who seeks care and whether they were asked to submit stool samples.

Once Dr. Scallan and other researchers estimate the national burden of foodborne illnesses, they can take to the next step in identifying risky foods, trends and education needed. Before FoodNet, no reliable data existed about the burden of Campylobacter, E. coli 0157, L. monocytogenes, Vibrio or Y. enterocolitica infections.

Cronquist says, “Through FoodNet we have a better picture of the diseases occurring in our communities and better resources to detect and act on outbreaks. National FoodNet data informs policy makers including FDA, USDA and HHS about trends in foodborne diseases.”

Though the study will be complete in 2010, Dr. Scallan says the results will generate more work.  Dr. Scallan says the U.S. is meeting three of the four Healthy People 2010 foodborne illness targets, since the occurrence of large multistate salmonella outbreaks are hindering meeting the last objective.   However, the outbreaks are revealing the gaps in the U.S. food safety system and the need to continue to develop and evaluate food safety practices as food moves from farm to table.

“If you think of all of the different steps along the way before food gets to the plate, there is a large group of people to educate from the farm to the consumer,” Dr. Scallan explains.  “It’s important to recognize it’s not just the consumers who need to be educated.”

Several Colorado School of Public Health students have worked on foodborne illness projects at CDPHE with the FoodNet surveillance system.  In the future, Cronquist and Dr. Scallan plan to involve more students in surveying communities when outbreaks occur.

“I am really hoping that by being at the Colorado School of Public Health I can help connect the school more to FoodNet,” she says. “I hope we can train the students to do some of the survey calling when there are outbreaks and further connect CDC, CDPHE and the Colorado School of Public Health.”