Are Foodborne Illnesses Becoming More Common in the U.S.?

Answers to your questions about the news.
Sept. 28 2011 4:32 PM

Fear the Cantaloupe

Are foodborne illness outbreaks on the rise?

Cantaloupe. Click image to expand.
Cantaloupe was the source of a recent salmonella outbreak

A listeria outbreak traced to cantaloupes has killed 13 people and sickened 72. It's the second cantaloupe-related incident this year, as the benign-looking orange melon was responsible for an outbreak of Salmonella panama that began in February. The CDC has also reported foodborne illness outbreaks this year from papayas, alfalfa sprouts, bologna, hazelnuts, and turkey (twice). Are foodborne illness outbreaks becoming more common?

Not at all. Between 1996 and 2010, the incidence of foodborne infection actually decreased by 23 percent. Most of that progress, however, occurred in the earlier part of the survey period, and infection rates have remained relatively steady since 2006. It's important to keep these data in perspective. Just 18 of the 2.4 million deaths (PDF) in the U.S. in 2007 were due to foodborne illness. About five times as many people die each year from insect stings as from contaminated food. If you're young and healthy, you're even less likely to die from a bad meal.

Advertisement

While public-health authorities have made substantial progress against food contamination over the past 15 years, a couple of bugs have frustrated them. Salmonella infections have not eased since 1996, and have increased slightly since 2006. Salmonella is a very adaptable pathogen. It can live in the gut of virtually any wild or domesticated species and can thrive in many plants as well. Outbreaks have been traced to poultry, eggs, pork, beef, grapes, and beans, to name just a few. When officials find a way to prevent infections from one food source—for example, by improving sanitation in chicken slaughterhouses—salmonella appears in a new, often completely unexpected, food. Scientists are still trying to figure out how between 2006 and 2009 the bug managed to grow in jars of peanut butter, a high-fat food previously thought inhospitable to bacterial proliferation. There was even a salmonella outbreak traced to marijuana.

There are a couple of other factors at work. The microbes that occur naturally in your gut produce acids that kill salmonella, but antibiotics can decimate your intestinal flora. People used to fight off the infection with ease; now we are somewhat more vulnerable. In addition, many children contract salmonella from their pet reptiles and turtles. The government has made little progress in preventing pet-borne salmonella infections.

The real trending foodborne illness is vibrio. It's much less common than salmonella, but its incidence is up 115 percent since 1996. The most common form of the disease in the United State is Vibrio parahaemolyticus, which is contracted from shellfish. (Vibrio cholerae, which patients usually get from drinking contaminated water, is more common worldwide.) The disease is on the rise because our infrastructure is deteriorating, and sewage keeps leaking into the coastal waters that shellfish inhabit.

Global warming may also be an issue, although scientists haven't yet proved the connection. Vibrio parahaemolyticus doesn't grow well in cold water, which is why people in the Chesapeake Bay know to limit their oyster consumption to months that contain the letter R—that is, anytime but May, June, July, and August. However, warming ocean waters may be lengthening the vibrio season. Epidemiologists are also seeing increased outbreaks of the disease in the Pacific Northwest, a region that used to be too cold for the pathogen to thrive.

Got a question about today's news? Ask the Explainer.

Explainer thanks A.M. Saeed of Michigan State University and editor of Salmonella enterica Serovar Enteritidis in Humans and Animals: Epidemiology, Pathogenesis, and Control, and O. Colin Stine of the University of Maryland.

Brian Palmer writes about science, medicine, and the environment for Slate and the Natural Resources Defense Council. Email him at explainerbrian@gmail.com. Follow him on Twitter.

TODAY IN SLATE

Justice Ginsburg’s Crucial Dissent in the Texas Voter ID Case

The Jarring Experience of Watching White Americans Speak Frankly About Race

How Facebook’s New Feature Could Come in Handy During a Disaster

The Most Ingenious Teaching Device Ever Invented

Sprawl, Decadence, and Environmental Ruin in Nevada

View From Chicago

You Should Be Able to Sell Your Kidney

Or at least trade it for something.

Space: The Next Generation

An All-Female Mission to Mars

As a NASA guinea pig, I verified that women would be cheaper to launch than men.

Terrorism, Immigration, and Ebola Are Combining Into a Supercluster of Anxiety

The Legal Loophole That Allows Microsoft to Seize Assets and Shut Down Companies

  News & Politics
Jurisprudence
Oct. 19 2014 1:05 PM Dawn Patrol Justice Ruth Bader Ginsburg’s critically important 5 a.m. wake-up call on voting rights.
  Business
Business Insider
Oct. 19 2014 11:40 AM Pot-Infused Halloween Candy Is a Worry in Colorado
  Life
Outward
Oct. 17 2014 5:26 PM Judge Begrudgingly Strikes Down Wyoming’s Gay Marriage Ban
  Double X
The XX Factor
Oct. 17 2014 4:23 PM A Former FBI Agent On Why It’s So Hard to Prosecute Gamergate Trolls
  Slate Plus
Tv Club
Oct. 20 2014 7:15 AM The Slate Doctor Who Podcast: Episode 9 A spoiler-filled discussion of "Flatline."
  Arts
Behold
Oct. 19 2014 4:33 PM Building Family Relationships in and out of Juvenile Detention Centers
  Technology
Future Tense
Oct. 17 2014 6:05 PM There Is No Better Use For Drones Than Star Wars Reenactments
  Health & Science
Bad Astronomy
Oct. 20 2014 7:00 AM Gallery: The Red Planet and the Comet
  Sports
Sports Nut
Oct. 16 2014 2:03 PM Oh What a Relief It Is How the rise of the bullpen has changed baseball.