Diced onions, cookie dough, flour, alfalfa sprouts, peanut butter — what do these very different foods have in common?
They all have been contaminated by salmonella, which sickens an estimated 1.35 million people in the United States each year. Infections from the bacteria — the most frequently reported cause of food-borne illness, according to the Department of Agriculture — can lead to symptoms such as fever, diarrhea and abdominal pain that may last for days.
People often get sick with salmonellosis, the infection caused by the bacteria, after eating undercooked meat or other contaminated foods, but the microbes can lurk in many other places, too. “There’s all these different pathways that can lead to human illness,” said Dr. Louise Francois Watkins, a physician with the Enteric Diseases Epidemiology Branch of the Centers for Disease Control and Prevention.
Here’s what you need to know about these sneaky bacteria, and how to keep yourself and your family safe.
How do infections happen?
One reason so many people are infected each year is that the bacteria naturally grow in the intestines of several animals, including chickens, birds and cows, said Martin Wiedmann, a veterinarian and food scientist at the Cornell University College of Agriculture and Life Sciences.
Animals harboring the bacteria usually don’t seem sick, said Dr. Francois Watkins.
When livestock are butchered, the bacteria in their intestines can contaminate the meat. One out of every 25 packages of chicken sold at grocery stores contains salmonella, according to the C.D.C. Anything that touches the raw meat can then become contaminated, Dr. Wiedmann said. If you touch the bacteria on a surface and then touch your mouth, you could get sick.
Because the bacteria thrive in animal intestines, they also wind up in animal feces — and then, sometimes, on animal feet and fur.
That can allow salmonella to spread to other locations, including crop fields and food processing plants, where the bacteria can contaminate produce and packaged foods.
What happens if I’m infected with salmonella?
Individuals who are exposed to salmonella usually start to feel sick six hours to six days later, Dr. Francois Watkins said. Most infections are mild and last between four and seven days. Although salmonella can afflict people of all ages, infections most often occur in children under 5 years old, in part because their immune systems aren’t fully developed.
The infection typically clears on its own, Dr. Francois Watkins said. But the C.D.C. recommends contacting a medical provider if you have diarrhea and a fever above 102 degrees; if diarrhea continues for more than three days without improving or becomes bloody; or if you are so dehydrated that you’re urinating very little.
Because few people visit the doctor when they’re sick from salmonella, and even fewer are tested for it, most people never know they have it. “Only one out of 30 cases of salmonella are actually detected and confirmed by the health care system,” said Andrea Etter, a food scientist and salmonella researcher at the University of Vermont.
Some people develop reactive arthritis after salmonella infections and experience joint pain, eye irritation or painful urination that can persist after the infection has cleared. In rare instances, salmonella can spread through the blood and cause blood infections, meningitis and other infections, Dr. Wiedmann said. Salmonella infections are responsible for 26,500 hospitalizations and 420 deaths in the United States each year.
What can I do to avoid it?
If you own pets or livestock, never kiss them and always wash your hands after handling them, Dr. Etter said. Ideally, wash their food and water containers in a utility sink or in the bathtub, but if you must use a kitchen or bathroom sink, disinfect it afterward.
Always cook meats to the minimum internal temperatures recommended by the U.S.D.A., Dr. Wiedmann said. “It’s very important to not just rely on your senses, but actually measure the temperature,” he said.
When you’re not eating cooked foods, refrigerate them. “Warmth can allow bacteria to multiply, so you want to get your food into a refrigerated area under 40 degrees as quickly as you can,” Dr. Francois Watkins said.
To prevent contaminating your kitchen and other foods while preparing raw meats, use separate cutting boards and utensils, Dr. Wiedmann said. Keep in mind that packages containing raw meat can leak, so store them apart from other foods or wrap them in a bag for protection.
After cooking raw meat, wash your hands and disinfect surfaces that may have been contaminated, Dr. Francois Watkins said. Dr. Etter suggested microwaving any sponges used during the cleaning process for one minute on high while the sponges are wet, which will kill most bacteria.
Finally, never rinse raw meats — including chicken or turkey — with water before you cook them. “It doesn’t do anything,” Dr. Etter said, “except spread salmonella all over your sink.”
