What to Know About E. Coli

An outbreak linked to organic carrots has sickened 39 people. Here’s how to stay safe.

The Centers for Disease Control and Prevention announced on Sunday that 39 people had been sickened and one person had died in an E. coli outbreak linked to organic carrots sold by Grimmway Farms.

E. coli has also been traced to other foods this year, including slivered onions served at McDonald’s stores and organic walnuts. The outbreak tied to McDonald’s has been linked to 34 hospitalizations and 1 death.

Contaminated vegetables are among the primary sources of E. coli outbreaks, which are responsible for an estimated 265,000 illnesses annually. Most infections, however, are not diagnosed or tracked by the C.D.C. because people often recover on their own without visiting a doctor, said Laura Gieraltowski, the deputy branch chief of the C.D.C.’s foodborne outbreak response team.

“It’s estimated that for every one reported E. coli illness, there are likely 26 others that go unreported,” Dr. Gieraltowski said.

Here’s what you need to know about E. coli to stay safe.

Where You’ll Find the Bacteria

There are many different kinds of E. coli, and most of them are harmless to humans, said Edward G. Dudley, a microbiologist and the director of the E. Coli Reference Center at Pennsylvania State University.

Some types do, however, make people sick, he said. Those that most commonly cause illness in humans, known as Shiga toxin-producing E. coli, primarily reside in cow intestines, which is why they often contaminate ground beef. The E. coli bacteria implicated in the McDonald’s outbreak are a type of Shiga toxin-producing E. coli.

Because these bacteria eventually work their way out of animal intestines and into feces, they can also contaminate farm soil — that’s why E. coli outbreaks are often tied to produce, Dr. Dudley said. They can also contaminate ponds, lakes and rivers.

An Ounce of Prevention

The best way to avoid getting sick from E. coli is to take precautions when preparing food, said Matthew Wise, the chief of the C.D.C.’s outbreak response and prevention branch. Keep raw meat and poultry separate from other foods and wash your hands thoroughly after handling them. Cook meat and other proteins to the appropriate temperature to kill bacteria that may be lurking inside, he said, and store leftovers in the refrigerator within two hours to slow bacterial growth.

Washing your hands often is a good idea whether or not you’re handling food, as E. coli can spread through contaminated surfaces or hands.

Since E. coli can sometimes contaminate raw foods — such as produce and nuts — it’s important to keep an eye on food recalls and throw away any recalled products, Dr. Wise said.

The C.D.C. also recommends that people wash fruits and vegetables under running water, consume only pasteurized milk and fruit juices and avoid eating raw dough or batter. You should also avoid swallowing water while swimming in untreated lakes or rivers.

If Someone Gets Sick

People typically develop symptoms such as diarrhea, vomiting, a fever of less than 101 degrees and abdominal cramps within three to four days of consuming contaminated food.

These can be similar to the symptoms of other, more common food-borne illnesses, such as those caused by salmonella bacteria, which sickens an estimated 1.35 million people nationwide each year, or norovirus, which sickens around 19 to 21 million Americans annually. The bacteria Listeria monocytogenes, by comparison, causes only an estimated 1,600 illnesses.

One way to distinguish an E. coli infection from other issues is that people infected with E. coli often have blood in their diarrhea, said Dr. Robert Bonomo, a professor of medicine at the Case Western Reserve University School of Medicine.

Abdominal pain that results from an E. coli infection is also usually worse than it is for other diarrheal illnesses, said Dr. William R. Miller, an infectious disease physician at Houston Methodist Hospital.

Dr. Wise suggested contacting a doctor if you, or a family member, have these symptoms or have had diarrhea for more than three days. Although most people recover within five to seven days without treatment, children under 5, adults over 65 and people with compromised immune systems are at a higher risk for serious complications.

Hemolytic uremic syndrome develops in 5 to 10 percent of those diagnosed with a Shiga toxin-producing E. coli infection, and among children, it is the most common in those under 5.

Doctors typically monitor patients for such complications and try to keep them hydrated until they recover. They typically do not treat infections with antibiotics or nonsteroidal anti-inflammatory drugs (such as ibuprofen), because these medications can increase the risk of hemolytic uremic syndrome, Dr. Miller said.

Anti-diarrheal drugs are a bad idea when you have E. coli, too. “You want your body flushing it out,” Dr. Dudley said.

Food Safety Issues and How to Avoid Them

• E. Coli: A deadly outbreak spurred removal of onions by a major food supplier in the Mountain West. Taco Bell, KFC, Burger King and Pizza Hut have stopped serving onions at various locations.
• Listeria: A listeria outbreak has been linked to Boar’s Head deli meats, leading to a recall of seven million pounds of the company’s products. Here’s what to know.
• Elevated Lead Levels: One dozen of 36 cinnamon products tested by a consumer group contained elevated levels of lead, according to a study that reinforced concerns about metals in foods after tainted cinnamon applesauce poisoned dozens of children last year.
• Refreezing Food: Shuttling dishes and ingredients from fridge to freezer and back again can be totally fine, as long as you follow these guidelines.
• Norovirus: The virus is extremely contagious, and, as anyone who has had it can tell you, extremely unpleasant.
• Salmonella: People often get sick with salmonellosis, the infection caused by the bacteria, after eating undercooked meat or other contaminated foods.