Salmonella can be deadly. Here’s how to protect yourself from it.

Salmonella has struck again. Grocery stores across the United States recalled cantaloupes in early December after discovering that whole and pre-sliced portions of the fruit were responsible for illnesses—and two deaths—across 34 states. The contamination was also found in Canada, where public health officials also ordered a recall. 

Such outbreaks are fairly common: The U.S. Centers for Disease Control and Prevention says salmonella bacteria cause more than a million infections, thousands of hospitalizations, and more than 400 deaths every year in the United States—illnesses that most often begin as a result of handling or consuming infected food. 

What is salmonella?

“Salmonella is a bacteria—so not to be confused with a virus,” says Brian Coombes, chair of the biochemistry and biomedical sciences department at McMaster University in Hamilton, Ontario. The source is “usually contaminated food—sometimes contaminated water—but in North America mostly contaminated food, because we have good water hygiene and good water sanitation.”

An infection with salmonella can look a lot like stomach flu—the symptoms include diarrhea, fever, and stomach cramps, and last between four to seven days.

What foods are most at risk?

“It really runs the gamut,” Coombes says. Salmonella is often found in vegetables and fruits—which, after all, are usually grown outdoors and can come into contact with contaminated soil, manure, and water. “Most people don't cook their fruits before they eat them. Hopefully they wash them. But people also like to eat raw vegetables.” 

(Which leafy greens are the healthiest—and which might make you sick?)

Meat can also be problematic—especially, but not only, if it’s undercooked. “The concern is you handle that raw chicken before cooking  and it gets on your hands and you don't wash your hands,” says Scott Roberts, the associate medical director in charge of infection prevention at Yale School of Medicine. Undercooked eggs and dairy products can also be a problem.

Is salmonella contagious?

Yes. “Most of the time it's [transmitted] person-to-food-to-person, or animal-to-person directly, or animal-food-person,” Coombes says. “But can you spread salmonella infections from person to person? Most definitely.”

Infected people need to be careful, even after symptoms end. “I think most people are most contagious when they have diarrhea, and when the diarrhea resolves the contagiousness goes away,” Roberts says. “But there are these chronic carriers who can still have it and spread it.” That condition can last for several weeks—or even a few months.

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How harmful is it to humans?

“In most people, I would say this is a self-limited illness that will go away in a few days, and you really don't have to worry about it,” says Roberts. The biggest problem they’ll face during this time is usually dehydration. 

In a few cases, though, “people get quite critically sick and need to get into the hospital because of an immune suppression,” Coombes says. Those acute cases can be difficult to treat. “The challenge that clinicians are facing now is that salmonella and other bacteria … are becoming very resistant to many of our existing antibiotics,” he says. “There’s no pill on the shelf that can actually work against certain strains.”

(Superbugs were already on the rise. The pandemic likely made things worse.)

The most vulnerable to acute infection? People under five or over 65.

What about pets?

“We really don't worry too much about diseases being passed back and forth from pets to humans, but salmonella is one where we do need to worry about that,” says Roberts. Reptiles—including turtles and lizards—are more frequently carriers of the bacteria, which is one reason the CDC warns against keeping those animals as pets if you have young children. Live poultry, as well as dogs and cats, can also be carriers.

Those animals might not show warning signs. “The animal may be fine or it may be sick, but certainly there can be asymptomatic infection in these individual pets who then can pass it to humans through some sort of fecal or oral contamination,” Roberts says. “Somebody managing a litter box of a cat and not washing their hands, for instance, is a recognized mode of transmission.”

(What we know about a mysterious respiratory disease spreading in dogs.)

How can you protect yourself from salmonella?

“The best way to stop the spread is to wash the hands,” Roberts says, and to make sure “your foods are adequately cooked, your vegetables and your fruits are adequately washed.”

Coombes agrees, emphasizing “common-sense food hygiene.” He advises against “cross-contaminating utensils that you use in the kitchen—especially if you've chopped up raw chicken,” he says. “You wouldn't then go use that knife to dice your vegetables for that meal. You'd wash things or use a different knife.”

Despite the concerns that arise whenever an outbreak or recall make the news, Coombes says, “I do believe that our food supply chain is quite safe. 

“There's lots of rules and regulations around what goes out the door to sell to people to eat, and there's lots of testing that happens sort of at the source,” he says. “And if there is contamination that's detected, the food product is recalled, and most people don't even know about it because it never hits the shelf.”