Expert Commentary

Foodborne illness: Causes, identification and costs

Foodborne illness can hide in our favorite comestibles. Luckily, researchers are developing tools to identify outbreaks and mitigate risks.

salad- seems harmless enough, till you eat it

A lunchtime salad seems innocuous enough — until a couple days later, when you’re rushing between the bathroom and your sick bed. The culprit? E. coli, a bacteria commonly transmitted through food or water that can cause serious illness. Outbreaks happen regularly, and E. coli is just one of many agents that transmit foodborne illness — others include salmonella and listeria.

According to a U.S. Centers for Disease Control and Prevention report, in 2015, 902 foodborne disease outbreaks were reported, which encompassed over 15,000 illnesses, 950 hospitalizations and 15 deaths. Outside of known outbreaks, the CDC estimates that 48 million people become ill from foodborne pathogens each year.

How does food become tainted? As they say, it happens. Often E. coli is spread through fecal contamination; the same goes for norovirus, the most common cause of restaurant-associated outbreaks with a single confirmed source. Salmonella in eggs is spread through poultry droppings or infected laying hens.

While food safety measures like washing produce and cooking meat and eggs all the way through can remove or kill bacteria and mitigate some of the risk of foodborne illness, these methods aren’t foolproof. A study published in 2017 in Food Science & Nutrition looked at whether washing ready-to-eat mixed salad greens and romaine lettuce inoculated with E. coli got rid of potentially harmful bacteria. They found that “only washing in a high flow rate (8 L/min) resulted in statistically significant reductions.” Another study points out the heightened risk that prepared salads pose, given the contamination potential of leafy vegetables, along with the added intermingled proteins which introduce the risk of cross-contamination and provide “an excellent substrate for bacterial growth.”

Before you swear off food entirely, swapping chewing for sipping in an attempt to mitigate risk, consider that meal replacement products are not immune. A study published in Clinical Infectious Diseases in 2018 documents a multistate outbreak of salmonella in a meal replacement shake powder.

Another wrinkle — though most foodborne illnesses run their course after a few miserable days, more serious infections might require treatment with antibiotics. A study published in Epidemiology and Infection in 2017, however, indicates that the widespread problem of bacterial resistance also affects food outbreaks — 21 percent of salmonella outbreaks studied in the paper were resistant.

While it might seem that the threat of disease lurks at every bite, researchers are developing new strategies to identify and map outbreaks. A 2017 paper published in the Journal of Food Protection outlines a geospatial mapping effort of early-onset outbreaks, which might help identify likely ports of entry for contaminated produce. Other research provides worldwide estimates of which foods most commonly cause foodborne illness. Elsewhere, the internet provides forums for crowdsourcing foodborne illness reports, and scholars are using platforms not dedicated to the purpose, like Twitter and Yelp, to identify outbreaks. A Twitter-based system used to find potential sources of outbreaks was found to be “64 percent more effective than the current state of the art;” a Yelp-based system that monitors restaurant reviews has identified 10 outbreaks and nearly 9,000 complaints of foodborne illness in New York City over five years.

A brush with foodborne illness, or the mere threat of illness, is often enough to put people off the offending item for some time. Multiple studies document how recalls and food safety scares affect product demand. A working paper presented at the Southern Agricultural Economics Association’s 2017 annual meeting found that a salmonella outbreak in ground beef reduced purchases by 17 percent in Utah in the month following the recall. A study published in 2016 in Food Policy finds that in the weeks following a December 2003 Bovine Spongiform Encephalopathy (BSE) incident in the United States, households bought 26 percent less beef per person, on average. From this figure, the authors estimate the recall cost the beef industry around $97 million. Another study looks at the impact of recalls on stock prices, finding that shareholders’ wealth is reduced by an average of 1.15 percent in the five days following a recall of a “serious food safety hazard.” This translates to about a $109 million reduction, the authors write — a big loss for lost appetites.