You get salmonella by swallowing the bacteria, most often through contaminated food, but also through contact with animals or infected people. The bacteria enter your digestive tract and cause an infection that typically starts 6 hours to 6 days after exposure and lasts 4 to 7 days. In the United States, salmonella causes an estimated 1.28 million illnesses every year, making it the leading cause of death from foodborne illness, with roughly 238 deaths and 12,500 hospitalizations annually.
Contaminated Food
Food is the most common route. The bacteria live in the intestines of animals, so any animal-based product can carry salmonella if it hasn’t been properly handled or cooked. Poultry and eggs are the most frequent culprits, but ground beef, pork, and unpasteurized dairy products are also common sources. Raw fruits and vegetables can pick up the bacteria too, either from contaminated irrigation water, soil fertilized with animal waste, or contact with raw meat during preparation.
Eggs deserve special attention because contamination doesn’t always come from the outside. With most foods, salmonella sits on the surface and gets killed by cooking. But hens infected with a specific strain can pass the bacteria directly into the egg through their ovaries before the shell even forms. That means a perfectly clean, uncracked egg can still harbor salmonella inside. This is why undercooked or runny eggs carry real risk, and why recipes calling for raw eggs (like homemade mayonnaise or certain cookie doughs) are a common source of infection.
Cross-Contamination in the Kitchen
You don’t have to eat the contaminated food itself to get sick. Salmonella spreads easily from one surface to another during meal prep. Cutting raw chicken on a board and then using the same board for salad, or handling raw meat and touching a faucet handle without washing your hands first, is enough to transfer the bacteria. Salmonella can survive on dry kitchen surfaces for up to 32 hours, so wiping down a counter hours later without sanitizing it may not be enough.
Knives, cutting boards, dish towels, and your own hands are the most common vehicles for cross-contamination. The fix is straightforward: use separate cutting boards for raw meat and ready-to-eat foods, wash hands with soap and water for at least 20 seconds after handling raw animal products, and clean surfaces with hot soapy water followed by a sanitizer.
Contact With Animals
Animals that look perfectly healthy can carry salmonella in their intestines and shed it in their droppings without ever showing signs of illness. The highest-risk animals are reptiles, amphibians, and poultry, but dogs, cats, rodents, and farm animals can all be carriers.
Reptiles and amphibians are a particularly underappreciated source. Turtles, snakes, bearded dragons, frogs, and salamanders frequently carry salmonella and contaminate their tanks, bedding, toys, and water. The U.S. Food and Drug Administration banned the sale of small turtles (shells under 4 inches) back in 1975 specifically because children were getting sick from handling them. Stressed reptiles, or those kept in overcrowded or poorly maintained enclosures, shed even more bacteria.
Children are at higher risk from animal contact because of developing immune systems, inconsistent hand-washing, and a tendency to put their hands and objects in their mouths. Research from Ontario, Canada found that salmonella patients who reported reptile or amphibian contact were generally younger than those infected through other routes. Petting zoos, farms, fairs, and even classroom animals can all be sources of exposure.
Backyard chicken coops have become a growing source of salmonella outbreaks. The bacteria live in the birds’ droppings and can coat feathers, nesting boxes, and coop surfaces. You don’t need to touch the droppings directly. Handling the birds, collecting eggs, or cleaning the coop and then touching your face is enough.
Person-to-Person Spread
Salmonella can pass from one person to another, though this is less common than food or animal transmission. Someone with an active infection sheds the bacteria in their stool, and if they don’t wash their hands thoroughly after using the bathroom, they can transfer it to surfaces, shared food, or directly to other people. Sexual contact, particularly oral-anal contact, is another documented route of transmission.
How Many Bacteria It Takes
It takes surprisingly few salmonella organisms to make you sick. For the common type of salmonella infection (the kind that causes diarrhea and stomach cramps), roughly 1,000 bacteria are enough to cause illness in a healthy adult. That’s a tiny number, easily present in a single bite of undercooked chicken or a splash of raw egg. People with reduced stomach acid, weakened immune systems, or older adults can get infected with even fewer organisms, which is one reason these groups face higher risk of severe illness.
Safe Cooking Temperatures
Heat kills salmonella reliably, but the food has to reach the right internal temperature throughout. A meat thermometer is the only way to know for sure, since color and texture aren’t reliable indicators. The USDA recommends these minimums:
- All poultry (whole birds, breasts, thighs, wings, ground poultry): 165°F (73.9°C)
- Ground meats (beef, pork, lamb): 160°F (71.1°C)
- Eggs and egg dishes: 160°F (71.1°C)
Whole cuts of beef and pork can safely be cooked to a lower temperature (145°F with a 3-minute rest) because bacteria typically only live on the surface of intact muscle. Ground meat needs a higher temperature because grinding mixes any surface bacteria throughout the product.
Other Ways to Reduce Your Risk
Refrigeration slows salmonella’s growth but doesn’t kill it. Keep your fridge at 40°F or below and don’t leave perishable food at room temperature for more than two hours. Store raw meat on the lowest shelf so juices can’t drip onto other foods.
After handling reptiles, amphibians, chicks, or any live poultry, wash your hands immediately. Don’t let these animals roam in kitchens or anywhere food is prepared. Keep reptile habitats and supplies away from kitchen sinks.
Wash produce under running water before eating it, even if you plan to peel it. A knife slicing through a contaminated rind can push bacteria into the flesh. And if someone in your household has a salmonella infection, pay close attention to bathroom hygiene and avoid sharing towels until they’ve fully recovered.