We’ve all been there before: One minute you’re chowing down on something delicious, and the next minute (well, usually several hours or even days later) you’re stuck on the toilet, clutching a trash can, and hoping someone will put you out of your misery. According to the Centers for Disease Control and Prevention (CDC), about 48 million Americans get some form of food poisoning each year. There are over 250 foodborne illnesses, most of which are caused by viruses, bacteria, or parasites. While extremely unpleasant, these conditions are usually quickly taken care of by our immune system. In some cases, however, food poisoning can be serious, even life-threatening. The CDC reports that approximately 128,000 people are hospitalized annually because of foodborne pathogens, and about 3,000 die.
The CDC explains that any food can harbor disease-causing germs, but "raw foods of animal origin are the most likely to be contaminated, specifically raw or undercooked meat and poultry, raw or lightly cooked eggs, unpasteurized (raw) milk, and raw shellfish." Fruits and vegetables, especially when eaten uncooked, are also common avenues for food poisoning. Contamination can happen in the field, during processing, or in the kitchen. People can get sick because of cross-contamination, insufficient cooking, and improper storage of leftovers. While you don’t necessarily need to avoid these "high-risk" foods, it’s a good idea to be mindful of how they’re handled, prepared, and stored, especially if you’re particularly vulnerable because of age, a weakened immune system, or pregnancy.
Leafy greens include lettuce, spinach, kale, cabbage, and bok choy among many others. While these veggies are packed with micronutrients, they’re also a major vector for a variety of foodborne illnesses. According to the CDC, leafy greens cause a large percentage of food poisoning cases in the United States. That’s because these vegetables are often eaten raw (such as in a salad or on a sandwich), so germs aren’t killed during the cooking process. While thoroughly washing produce is a good idea, it doesn’t necessarily remove all disease-causing pathogens. Germs most often found on leafy greens include E. coli, norovirus, Salmonella, Listeria, and Cyclospora.
While the symptoms of food poisoning vary somewhat based on which germ is causing the condition, the "unholy trinity" of abdominal cramps, nausea/vomiting, and diarrhea are almost universal (via Healthline). Abdominal cramping and pain can occur because of inflammation in your GI tract caused by the virus or bacteria, as well as your body’s own efforts to get the pathogen out as quickly as possible. These cramps can trigger nausea and vomiting. Many people experience an initial bout of very forceful vomiting as their body tries to get rid of the microscopic intruder. Diarrhea, defined as three or more loose or watery stools in a 24-hour period, is also common, thanks to abdominal cramps that speed up bowel movements and inflammation that prevents your intestines from effectively absorbing water as they normally would.
Raw or undercooked eggs
While the idea of gulping down a raw egg may sound disgusting to you, perhaps you enjoy authentic Caesar salad dressing or prefer your eggs with a runny yolk. But if you eat raw or undercooked eggs, you could be putting yourself at risk for serious foodborne illness. According Livescience, approximately 1 in 10,000–20,000 eggs are contaminated with Salmonella bacteria. If a chicken’s ovaries are infected with Salmonella, the bacteria can enter the egg as its being formed. Once the egg is laid, Salmonella-containing droppings can also contaminate the shell.
As the CDC explains, Salmonella are a group of bacteria that can cause a type of food poisoning called salmonellosis. Although there are more than 2,500 types of Salmonella, fewer than 100 cause disease in people. Symptoms of salmonellosis include fever, diarrhea, and stomach cramps and can appear anywhere from six hours to six days after exposure. This type of food poisoning usually lasts four to seven days, though some individuals may be sick for several weeks. The frequency and consistency of bowel movements may not return to normal for several months after the infection clears. Because of heavy use of antibiotics in both humans and livestock, many strains of Salmonella are becoming resistant to these drugs, making it harder to effectively treat severe cases of salmonellosis. About 1.35 million Americans get salmonellosis each year. Of those, approximately 26,500 will be hospitalized and 420 will die.
While most people know that undercooked chicken may contain Salmonella, there’s another bacteria that’s even more likely and that can also cause food poisoning. As the CDC notes, campylobacteriosis is a type of food poisoning caused by infection with Campylobacter bacteria. It causes an estimated 1.5 million illnesses in the United States each year, although many cases may go unreported. Cases are most common in summer. Many livestock animals carry Campylobacter in their intestines, liver, or other organs. Meat can become contaminated with the bacteria during the slaughtering process. Campylobacter is very common in raw meat. For instance, as much as one-quarter of raw chicken meat sold in grocery stores contains the bacteria. People become sick when they eat organs or meat from infected animals without thoroughly cooking them, or as the result of cross-contamination when preparing food. Individuals can also get Campylobacter from unpasteurized milk from an infected animal, or from fresh fruits and vegetables that have come in contact with contaminated soil or water. Only a very small amount of bacteria is needed to cause an infection.
Symptoms of campylobacteriosis begin two to five days after exposure and last about a week. The most common complaints are fever, stomach cramps, and diarrhea that is often bloody. Sometimes people may also experience nausea and vomiting. Some individuals may shed the bacteria in their stool for weeks after they recover.
If you like your burger bloody, you’re putting yourself at risk for Escherichia coli (E. coli) infection (via the Food and Drug Administration). According to the CDC, while there are many species of E. coli — many of which are even beneficial — some produce a toxin that causes food poisoning. This group is known as Shiga toxin-producing E. coli (STEC). They are also sometimes referred to as verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC). STEC causes approximately 265,000 infections in the United States each year, and about 36% of these are the result of one particular strain known as STEC 0157. Although widespread E. coli outbreaks garner a lot of press attention, only about 20% of E. coli food poisoning cases are part of a recognized outbreak.
STEC live in the intestines of ruminants like cattle. They shed the bacteria in their feces, and meat, milk, or other foods can become contaminated with this STEC-containing feces. It’s also possible to get a STEC infection from drinking contaminated water or eating food handled by someone with a STEC infection. The incubation period for STEC is usually three to four days, although symptoms can appear anywhere from one to 10 days after exposure. Unlike many other types of food poisoning, STEC symptoms usually begin slowly and gradually build. Severe abdominal cramps, diarrhea (usually bloody), and vomiting are the most common symptoms. A low-grade fever may also be present. Symptoms usually last five to seven days.
If you’ve got a cheese addiction, you may want to switch to the "hard stuff," particularly if you’re pregnant. That’s because soft cheeses are one of the foods most likely to cause listeriosis. According to the CDC, listeriosis is a relatively uncommon but potentially very serious form of foodborne illness caused by the bacteria Listeria monocytogenes. There are about 1,600 cases of listeriosis in the United States each year, although many more may go undocumented. That’s because most individuals’ bodies can clear the bacteria before they cause any harm. Pregnant women, newborns, those over 65, and people with weakened immune systems, however, can all experience symptomatic listeriosis. In these vulnerable groups, the bacteria spread from the GI tract to other parts of the body (known as invasive listeriosis), which requires hospitalization and can become life-threatening.
The CDC noted that symptoms of listeriosis appear one to four weeks after exposure. For pregnant women, the condition is usually relatively mild, with fever and flu-like symptoms such as muscle aches and fatigue. But the bacterial infection can lead to severe illness or death for her unborn baby. Older adults and those with a weakened immune system will also have a fever and flu-like symptoms, but may also experience headaches, confusion, loss of balance, and convulsions. In addition to soft cheeses, common food sources for listeriosis that pregnant women are cautioned against eating include sprouts, hot dogs, deli meats, smoked seafood, and unpasteurized milk.
Raw oysters are a delicacy, but they’re also dangerous. According to the CDC, Vibrio are a large group of bacteria that live in saltwater and brackish water. While there are many species, about a dozen can cause disease in humans, known as vibriosis. The three strains that cause vibriosis in the United States are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus. About 80% of Vibrio infections occur between May and October, when ocean temperatures are warmer and the bacteria thrive. About 80,000 cases of vibriosis are reported each year, and approximately 45,000 of those are caused by Vibrio parahaemolyticus. Most people (about 52,000 of the 80,000 annual cases) get vibriosis from eating contaminated food. While oysters are the main culprit, any raw or undercooked shellfish can be contaminated. The remainder of cases are the result of getting contaminated water in a wound, which can lead to a skin infection rather than GI upset.
Most people recover from vibriosis within about three days, but one in five people with Vibrio vulnificus will die of the condition, sometimes within just a day or two. The CDC notes that symptoms of gastrointestinal vibrio infection usually begin two to 48 hours after exposure and include watery diarrhea, nausea, stomach cramps, vomiting, fever, and chills. An oyster contaminated with Vibrio bacteria doesn’t look, smell or taste off, so you can’t trust your senses to keep you safe. It’s best to thoroughly cook oysters and other shellfish (via the CDC).
Raw or undercooked mussels
If you think you’re avoiding potential food poisoning by ditching the oyster bar for raw or lightly cooked mussels instead, think again. According to the Washington State Department of Health, "all bivalve shellfish such as clams, geoducks, mussels, scallops, and oysters can transmit norovirus." Mussels and other bivalves are filter feeders that pass water through their bodies in order to obtain food. If that water is contaminated with norovirus (from untreated human vomit or excrement), the shellfish will become infected.
As the name implies, norovirus is a virus. The Mayo Clinic notes that although often referred to as the "stomach flu," it isn’t related to influenza in any way. People get norovirus from contaminated food or water, touching contaminated surfaces, or close contact with sick individuals. Symptoms include the basics (cramping, diarrhea, and vomiting), along with a low-grade fever and muscle pain. Symptoms begin 12 to 48 hours after exposure and usually last one to three days. Individuals can continue to shed the virus in their stool for up to two weeks, meaning they could still infect others. Some lucky individuals experience no symptoms of norovirus infection but can still spread the disease. According to the National Foundation for Infectious Diseases, there are 19–21 million cases of norovirus in the United States each year, including 56,000–71,000 hospitalizations and 570–800 deaths.
Improperly home-canned fruits and vegetables
Be extra cautious if you enjoy canning your own fruits and vegetables. The Mayo Clinic says that home-canned low-acid foods such as fruits, vegetables, and fish are often the source of foodborne botulism. Botulism has a well-deserved reputation as one of the most serious forms of foodborne illness, but luckily it’s quite rare. According to the CDC, there are about 110 cases of botulism in the United States each year, and only around 25% of these are foodborne botulism. (The remainder of cases consist of infant botulism and wound botulism.)
As the CDC explains, botulism is caused by toxins produced by the bacteria Clostridium botulinum, as well as occasionally Clostridium butyricum and Clostridium baratii. Clostridium botulinum itself rarely makes people sick, but under the right conditions, these bacteria produce a toxin that can cause nerve damage, muscle paralysis, and death. These conditions include a low- or no-oxygen environment, low acid, low sugar, low salt, a specific amount of water, and a particular temperature range. This is why it’s very important to follow canning recipes exactly to ensure you aren’t creating a perfect environment for these botulinum toxins.
The Mayo Clinic notes that symptoms typically begin 12 to 36 hours after ingesting the toxin and can progress rapidly. Common signs to look out for include dry mouth, difficulty swallowing and breathing, blurred vision, drooping eyelids, and facial weakness. Botulism is a medical emergency and can be fatal if left untreated.
Thanksgiving turkey and gravy
Sometimes, it’s not the food itself that makes food poisoning likely, but the circumstances under which it’s eaten. While people often look forward to their Thanksgiving feast all year, it can be a breeding ground for Clostridium perfringens (C. perfringens). According to the CDC, C. perfringens causes nearly one million illnesses in the United States annually. C. perfringens is a bacteria that, when ingested, releases a toxin that causes GI upset. People can get C. perfringens from eating infected undercooked meat, as well as from eating properly cooked meat and meat-based gravies that have been kept at an unsafe temperature (40°-140° F) for too long. That’s because C. perfringens make spores. While thorough cooking kills the bacteria, the spores can survive the oven or stove and, if allowed to sit in this dangerous temperature zone too long, will grow into new bacteria.
It’s not surprising, then, that C. perfringens outbreaks often appear in situations where food is cooked in large batches and sits out for long periods of time. This includes meals served at school cafeterias, nursing homes, prisons, soup kitchens, and events with catered food. Many C. perfringens cases happen in November and December and have been linked to holiday gatherings. Symptoms appear six to 24 hours after exposure and usually last less than 24 hours. The bacteria’s toxin causes stomach cramps and diarrhea, but vomiting and fever are rare.
Another "situational" food that puts you at higher-than-average risk of food poisoning is any meal eaten at a restaurant. When eating out, you have no control over who’s handling your food. This ups the chances that you might get sick from a Staphylococcus aureus (Staph) infection. In fact, according to a 2014 paper published in BioMed Research International, "outbreak investigations have found that improper food handling practices in the retail industry account for the majority of [Staph] outbreaks."
While most of us associate Staph with nasty skin infections, the toxins this bacteria produces can also cause food poisoning. According to the CDC, someone with Staph on their hands can transfer the bacteria to food when handling it. When you consider the fact that about 25% of humans have staph on their skin or in their noses, it’s easy to see why following food safety guidelines is so important. Although heat kills Staph, it doesn’t destroy the toxins that cause gastrointestinal illness. Foods that aren’t cooked after preparation, such as sandwiches and salads, pose the biggest threat.
Staph food poisoning tends to hit fast but resolve quickly. Symptoms can begin as soon as 30 minutes after eating contaminated food, though they may take up to eight hours to appear. The good news is that the illness lasts no longer than a day. Individuals experience sudden nausea, vomiting, and stomach cramps, and most also have diarrhea. Severe illness is rare.
According to the National Institute of Food and Agriculture, Bacillus cereus (B. cereus) is a disease-causing bacteria commonly found on a variety of foods, although steamed and fried rice is one of the most common avenues of infection. B. cereus infections can occur because food wasn’t cooked thoroughly or because food was left out too long. Like several other bacteria, B. cereus produce heat-resistant spores that can survive the cooking process. If food sits out too long at the right temperature, those spores will turn into new bacteria that produce harmful toxins once ingested. For B. cereus, the "danger zone" for toxin production is 77°–86° F.
B. cereus causes two types of food poisoning. The emetic type causes nausea, vomiting, and abdominal cramps and results from eating food that already contains B. cereus toxins. It causes symptoms one to six hours after ingesting contaminated food. The other form leads to diarrhea and is caused by enterotoxins produced by B. cereus spores once they’ve been ingested. Enterotoxins irritate the lining of the intestines. Symptoms of diarrheal B. cereus infections usually strike six to 15 hours after food is consumed, although most people feel better in 24 hours. While it may be common practice in some households to leave pots of rice at room temperature for long periods of time, it’s best to move leftovers to the fridge as soon as possible.
If you make your own fruit and vegetable juices at home or buy them fresh from a local juice bar, you could be setting yourself up for food poisoning. The Food and Drug Administration (FDA) warns that "when fruits and vegetables are fresh-squeezed or used raw, bacteria from the produce can end up in your juice." While commercially bottled juices are pasteurized to kill potential germs, juices you make yourself or buy made-to-order aren’t heat treated.
For most people, the majority of foodborne illness are extremely unpleasant but short-lived and cause no lasting harm. But foodborne pathogens such as the kinds commonly found on produce can cause a variety of complications, especially for individuals who are very young, very old, immunocompromised, or pregnant. For instance, while listeriosis may not have much of an effect on a pregnant woman, it can be devastating for her baby. Listeria infection during pregnancy causes death of the fetus in about 20% of cases, and death of the baby shortly after birth in about 3% of cases (via the CDC). In about 5–10% of cases of E. coli infection, individuals develop hemolytic uremic syndrome (HUS), a potentially life-threatening condition in which the kidneys stop functioning properly (via the CDC). In addition to causing food poisoning, Salmonella can also trigger reactive arthritis, which can last for months or years (via the CDC).
Raw alfalfa, clover, mung bean, and other types of sprouts carry an elevated risk of food poisoning, particularly from Salmonella, E. coli, and Listeria. The conditions needed to germinate seeds into sprouts are also the ideal conditions to nurture the growth of bacteria (via Healthline). A 2014 paper published in Foodborne Pathogens and Disease noted that there were 33 food poisoning outbreaks in the United States linked to sprouts from 1998 through 2010, including 28 caused by Salmonella, four by E. coli, and one by Listeria. These outbreaks sickened at least 1,330 people. The same year that paper was published, another major sprout-related outbreak of Salmonella sickened 115 people across 12 states (via the CDC).
When widespread outbreaks of food poisoning are traced to a particular food or manufacturer, a recall is issued. But food recalls can also help prevent outbreaks of foodborne illness before they even happen. According to Food Safety News, food recalls are overseen by a number of governmental agencies. Food recalls because of pathogens are considered a class I recall, meaning they represent "a health hazard situation in which there is a reasonable probability that eating the food will cause health problems or death." Sometimes contamination is discovered by the manufacturer or regulatory agencies during testing or inspection, but other times the situation isn’t apparent until after people have become sick. Most food recalls related to foodborne illness center on E. coli, Salmonella, and Listeria.
Raw dairy products
Some people believe that drinking raw (unpasteurized) milk or eating cheeses or yogurt made from raw milk offers more nutrition than consuming their pasteurized counterparts (via Healthline). But raw diary can harbor a whole host of disease-causing bacteria, including Salmonella, E. coli, Listeria, and Campylobacter. Between 1993 and 2012, there were 127 outbreaks of food poisoning linked to raw milk and other dairy products that sickened 1,909 people and hospitalized 144 (via the Food and Drug Administration).
While it’s easy to simply avoid raw dairy altogether, almost any food — even very nutritious ones — can cause food poisoning. So how do you minimize your risk of getting sick? When preparing food at home, the CDC recommends a commonsense four-step food safety protocol. First, be sure to thoroughly wash your hands before handling food, as well as all utensils, cutting boards, and surfaces. Second, avoid cross-contamination by keeping raw meat, seafood, and eggs separate from other food when grocery shopping, in the fridge, and during preparation. Always use a separate cutting board, utensils, and plates for raw meat and eggs. Third, cook meat to the proper internal temperature to ensure any harmful bacteria are killed. Finally, don’t let food sit in the "danger zone" (40°–140° F) long enough for bacteria to multiply. Refrigerate leftovers within two hours (or one hour if the ambient temperature is above 90° F). Always thaw frozen food in the fridge, cold water, or the microwave — never on the counter.