Originally appeared in the article, "How Bad is Salmonella Really? Experts Explain," by Kaitlyn Pirie for MSN on November 1, 2021.
Salmonella is famous enough nowadays that we know we’re not supposed to eat cookie dough—and to take notice when there’s an outbreak. But most of us don’t have a full understanding of how the bacteria can actually impact our health.
While salmonella infects 1.35 million Americans every year, according to the Centers for Disease Control and Prevention (CDC), the idea of a potential infection shouldn’t keep you up at night worrying about the food spread at every party you attend. “Taking some reasonable precautions can reduce the likelihood that you get sick,” says says Ferric Fang, M.D., professor of laboratory medicine and pathology as well as microbiology at University of Washington School of Medicine, “and if you do get sick, know that most people get better on their own because our bodies have pretty good defenses against these things.”
Here’s everything you need to know about salmonella to ensure that you and your family stay safe.
What is salmonella?
The human gut naturally contains lots of bacteria, but salmonella is a type of bacteria that is not normally found there. “It’s pathogenic, which means that when you get it and it starts to replicate or multiply in your gut, it causes illness,” says Mark Pimentel, M.D., associate professor of gastroenterology and director of the Medically Associated Science and Technology Program at Cedars-Sinai in Los Angeles.
What causes a salmonella infection?
The bacteria live in the intestines of animals (often because the animal ate contaminated food, drank contaminated water, touched infected feces from another animal, or had close contact with another infected animal) and then humans can contract salmonella in several ways:
- Petting an infected animal (even a pet!) or scooping their poop and then touching your mouth or food without washing hands thoroughly first
- Eating dairy or meat products from an infected animal
- Eating produce that’s been contaminated in the kitchen (say, you use the same cutting board for raw chicken and then salad prep) or on the farm (say, an infected animal defecates in the field or an employee harvesting in the field has salmonella and can’t make it to the bathroom or didn’t wash their hands after going to the bathroom—traces of the feces could end up on your lettuce)
What are the symptoms of salmonella?
The most common symptoms are diarrhea, fever, and abdominal pain—and they can develop anytime between 6 hours and 6 days after you ingest the bacteria. “Some people will get infected with salmonella and not know it and then they'll get rid of it,” says Dr. Fang. It may be that they were exposed to a very low number of bacteria in the first place or that their immune system took care of things so symptoms were relatively mild. However, if a person is immunocompromised or experiences a high fever, bloody stool, or diarrhea that lasts longer than a week, Dr. Fang says it’s a good idea to seek medical help.
How is salmonella diagnosed?
“The principal way to diagnose is with stool testing,” says Dr. Pimentel. “You have to collect the stool sample and they send it to the lab and look for evidence of salmonella.”
How is salmonella treated?
Typically, antibiotics can kill salmonella, but most healthy people who are diagnosed with the bacteria are only treated for the symptoms they exhibit (like IV fluids for dehydration) and not given antibiotics. “You have a lot of bacteria in your GI tract normally and those bacteria play an important role in helping to keep you healthy and also protecting you against infection,” explains Dr. Fang. “So if you interfere with the normal bacteria that colonize your GI tract, which are called microbiota, then it can make it easier for the salmonella to come back.” Not only that, overuse of antibiotics can lead to antibiotic resistance (meaning bacteria no longer respond to treatments that worked in the past) and research shows the number of antibiotic-resistant salmonella infections is on the rise in the United States. As a result, the CDC only recommends antibiotics to treat salmonella in people with severe cases or a weakened immune system; people who are over age 65 or over age 50 with a medical condition like heart disease; or babies younger than a year old.
Who is at risk for a salmonella infection?
There are a few populations of people who are at a higher risk of developing a salmonella infection:
- Immunosuppressed people: This includes people with infections like HIV as well as those taking certain immunosuppressive drugs. “It could even be something like steroids—it doesn’t have to be a really aggressive kind of therapy,” says Dr. Fang.
- People taking a proton-pump inhibitor or h2 antagonist: These medicines reduce stomach acid, which naturally helps kill microorganisms that we ingest. “People who take them are more susceptible to getting infected not just with salmonella, but a variety of causes of food poisoning,” says Dr. Fang.
- People with certain sexual practices: Fecal-oral contact increases the risk of acquiring GI infections from a sexual partner, according to Dr. Fang.
What are potential complications of salmonella?
Most cases of salmonella resolve without any serious complications. However, there are a few issues to be aware of:
- Aortitis: “Occasionally the salmonella gets out of the GI tract and into the blood and then it can seed to different organs,” says Dr. Fang. If there is atherosclerotic plaque in the large artery that carries blood from the heart (the aorta), that plaque can become infected with circulating salmonella and lead to aortitis, an infection that can be very difficult to treat, according to Dr. Fang.
- Irritable bowel syndrome (IBS): “About one in nine people who get food poisoning, whether it be salmonella or something else, will go on to develop irritable bowel syndrome from that food poisoning,” says Dr. Pimentel. At first, your initial salmonella symptoms will go away. “Then slowly, over a week to six weeks, you’ll start to get this weird bowel pattern that isn’t normal and it never goes back to normal,” explains Dr. Pimentel. “That’s called post-infectious irritable bowel syndrome and it’s a really huge problem these days.”
- Arthritis: About 5% of people who recover from a salmonella infection go on to develop reactive arthritis. Researchers aren’t sure exactly how this happens, but it’s thought that a protein produced by the bacteria might promote inflammation in the joints.
How can you prevent a salmonella infection?
In some instances (say, if food is contaminated in a restaurant) there’s not much you can do to prevent a salmonella infection, but here are some proactive measures you can take to reduce your risk of illness:
1. Fully cook meats.
Heating meats to internal temperatures recommended by the USDA will ensure that any salmonella lurking inside is killed. “So, you could have it in a hamburger and if you cook that hamburger thoroughly, you're not going to have salmonella,” says Dr. Fang, “but If you like the middle of your hamburger raw and it's contaminated, then you could get infected.”
2. Prevent cross-contamination.
Salmonella dies when food is cooked properly, but it can easily be transferred to foods you’ll eat raw and cause an infection. Here are some ways to prevent that from happening:
Use new, clean surfaces (cutting boards, plates, bowls, utensils, etc.) when you prep foods that don’t get heated (like salads). Along those same lines, it’s a good idea to wash utensils halfway through cooking meat. “That way you’re not continuously putting the original chicken juice back onto the chicken,” says Dr. Pimentel. Lastly, don’t wash poultry before cooking! You run the risk of splattering bacteria into the sink or the counter where you might place foods that won’t be cooked. “If you cook the chicken thoroughly, you don't have to worry that it was contaminated to begin with,” adds Dr. Pimentel.
3. Don’t cook for others when you’re sick.
“If you have a sudden onset of diarrhea that you didn’t anticipate, don’t be the food preparer for your house for those days,” advises Dr. Pimentel. “Even though you may be the cleanest person in the world, you shouldn’t be cutting the vegetables for other people in the household for a couple of days while you have that illness because you can spread it to others.”
4. Be picky at buffets.
“In a buffet, the food just sits and sits and sits in a warming tray,” says Dr. Pimentel. “Always look where the flame is underneath and scoop your food from where that flame is because that food is probably at the correct temperature to kill bacteria, but at the edges, it’s probably at the perfect temperature to cause growth.”
5. Avoid unpasteurized foods.
“The problem is that cattle can shed salmonella as well as other bacteria and unpasteurized milk can then be contaminated,” says Dr. Fang.
6. Wash hands after touching pets or scooping their poop.
Animals can carry salmonella and Dr. Fang says reptiles (including turtles and iguanas) are a common source of the bacteria. “In fact, in the case of reptiles, they’ll often show no signs of illness at all,” he adds.
7. Be extra cautious when traveling.
Many countries do not have the stringent regulations and monitoring for foodborne illnesses that we have in the U.S., according to Dr. Fang. Research your destination ahead of time and take extra precautions, particularly if you’ll be eating from street vendors or won’t have access to clean water.