Foodborne Illness: The 10 Germs Behind Most Food Poisoning, and How to Prevent Each One

What Foodborne Illness Actually Is

Foodborne illness is sickness that comes from eating contaminated food. USDA's Food Safety and Inspection Service (FSIS) puts it at an estimated 48 million illnesses and 3,000 deaths each year in the United States, and calls it preventable. Symptoms can start within minutes or take weeks to show up, and they often look like the flu: nausea, vomiting, diarrhea, or fever. That's why so many cases go unrecognized.

Everyone is at risk, but some people are at greater risk of serious illness or death. FSIS lists infants and young children, pregnant women and their unborn babies, older adults, and people with weakened immune systems, such as those with HIV/AIDS, cancer, diabetes, kidney disease, or a transplant. It also notes that some people get sick after swallowing only a few harmful bacteria, while others have no symptoms after swallowing thousands.

By the Numbers

From USDA FSIS's Food Safety and Food Safety Stats pages:

• 1 in 6 Americans gets a foodborne illness each year.
• Age 4 has the highest incidence of confirmed infections from food pathogens.
• Age 50 and up: reduced immunity puts people at greater risk of hospitalization from food pathogens.
• The Danger Zone is 40°F to 140°F, where bacteria multiply rapidly. Keep hot food at 140°F or warmer, cold food at 40°F or colder, and frozen food at 0°F.
• 66% of people don't use food thermometers correctly, and color is never a reliable sign that food is safe or done.
• Safe cooking temperatures: 145°F for steaks, chops, roasts, and fish (let meat rest 3 minutes); 160°F for ground meats and egg dishes; 165°F for poultry.

The 10 Germs on USDA's List

FSIS keeps a table of the main foodborne bacteria and other pathogens. Here it is in plain language. The timing and prevention details are USDA's.

• Salmonella (over 2,300 types). Where: raw or undercooked eggs, poultry, and meat; unpasteurized milk and juice; cheese and seafood; fresh fruits and vegetables. What it does: diarrhea, fever, and cramps, usually 12 to 72 hours after eating, lasting 4 to 7 days. It can be more severe, even deadly, with a weakened immune system. Prevent it: cook meat, poultry, and eggs to a safe temperature, skip raw or undercooked eggs and raw dairy, and wash produce.
• E. coli O157:H7. Where: uncooked beef (especially ground beef), unpasteurized milk and juices like fresh cider, raw fruits and vegetables, and water. It can also spread person to person. What it does: severe, often bloody diarrhea, cramps, and vomiting, usually with little or no fever, starting 2 to 8 days after eating (usually 3 to 4). Children under 5 are at greater risk of hemolytic uremic syndrome (HUS), which causes acute kidney failure. Prevent it: cook hamburgers and ground beef to 160°F, drink only pasteurized milk, juice, and cider, rinse produce under running water, and wash hands after diapers, the bathroom, and pets.
• Listeria monocytogenes. Where: ready-to-eat foods like hot dogs, lunch meats, cold cuts, and dry sausage; soft cheeses made with unpasteurized milk; smoked seafood; and store-made salads such as ham, chicken, or seafood salad. What it does: fever, muscle aches, and sometimes nausea or diarrhea. If it spreads to the nervous system it can cause headache, stiff neck, confusion, loss of balance, or convulsions. It can cause miscarriage or death in newborns. Prevent it: cook raw meat, poultry, and seafood, keep ready-to-eat foods away from raw foods and their juices, and wash hands. People with weakened immune systems should avoid hot dogs and deli meats unless reheated to 165°F or steaming hot, and should skip store-made deli salads and raw-milk cheeses.
• Campylobacter jejuni. Where: contaminated water, raw or unpasteurized milk, and raw or undercooked meat, poultry, or shellfish. What it does: diarrhea (sometimes bloody), cramping, abdominal pain, and fever, 2 to 5 days after eating and lasting up to 7 days. It can spread to the bloodstream. Prevent it: cook meat and poultry to a safe temperature, avoid unpasteurized milk, and wash hands after contact with feces.
• Clostridium perfringens, "the cafeteria germ." Where: meats, meat products, and gravy left for long periods on steam tables or at room temperature. What it does: intense cramps, nausea, and diarrhea 6 to 24 hours after eating, usually lasting about a day. Prevent it: keep hot food at 140°F or above, use a food thermometer, and discard perishable food left out more than 2 hours (1 hour above 90°F).
• Staphylococcus aureus (Staph). Where: found on the skin and in the noses of up to 25% of healthy people and animals, so it spreads through improper food handling. It multiplies quickly at room temperature and makes a toxin. What it does: severe nausea, cramps, vomiting, and diarrhea 30 minutes to 6 hours after eating, with recovery in 1 to 3 days. Prevent it: the toxin is heat-resistant and cooking won't destroy it, so stop contamination before it starts. Keep hot food above 140°F and cold food at 40°F or below, and wash hands and counters with hot, soapy water before and after preparing food.
• Clostridium botulinum (botulism). Where: improperly canned foods, garlic in oil, and vacuum-packed or tightly wrapped foods. What it does: the bacteria make a nerve toxin. Symptoms usually appear 18 to 36 hours after eating (as early as 6 hours or as late as 10 days): double or blurred vision, drooping eyelids, slurred speech, trouble swallowing, dry mouth, and muscle weakness. Untreated, it can progress to paralysis and death. Prevent it: don't use canned food that is swollen, leaking, punctured, cracked, deeply rusted, or dented badly enough to prevent normal stacking. Follow safe home-canning guidelines (your state university or county extension office has them) and boil home-canned foods for 10 minutes before eating.
• Shigella (over 30 types). Where: spreads person to person and through fecal contamination of food and water. Most outbreaks come from food, especially salads, handled by workers with poor hygiene. What it does: watery or bloody diarrhea, fever, and cramps, 1 to 2 days after exposure, usually resolving in 5 to 7 days. Prevent it: handwashing with soap and water before handling food and after the bathroom, diapers, or contact with someone who is ill.
• Cryptosporidium. Where: soil, food, water, and contaminated surfaces, including swallowing water from a pool or lake. What it does: dehydration, weight loss, cramps, fever, nausea, and vomiting, starting 2 to 10 days after infection and lasting 1 to 2 weeks. It can be more serious with a weakened immune system. Prevent it: wash hands before and after handling raw meat and after diapers, the bathroom, or touching animals, and don't drink untreated water from shallow wells, lakes, rivers, springs, ponds, or streams.
• Vibrio vulnificus. Where: raw or uncooked seafood, especially oysters. What it does: in healthy people, diarrhea, stomach pain, and vomiting. For people with weakened immune systems, particularly with underlying liver disease, it can cause a blood infection and death. Prevent it: don't eat raw oysters or other raw shellfish, cook oysters, clams, and mussels thoroughly, keep cooked seafood away from raw seafood and its juices, and refrigerate cooked shellfish within 2 hours.

The Pattern Across All Ten

Read the prevention columns side by side and the same few habits keep showing up: wash your hands with warm water and soap for at least 20 seconds; cook meat, poultry, and eggs to a safe temperature with a food thermometer; keep raw foods and their juices away from ready-to-eat foods; keep hot food hot (140°F or above) and cold food cold (40°F or below); refrigerate leftovers promptly; and stick to pasteurized milk and juice. FSIS's four-word version is Clean, Separate, Cook, Chill, which I cover in this guide.

If You Think a Food Made You Sick

Call a healthcare provider if you're worried about an illness, especially if you're in a higher-risk group. If a meat, poultry, or egg product caused a problem, FSIS takes reports through its Electronic Consumer Complaint Monitoring System, and the USDA Meat and Poultry Hotline (1-888-MPHotline, 1-888-674-6854) answers food safety questions. Keep the packaging if you can, since lot codes and dates are what investigators use.

For what's being recalled right now, see my latest recall roundup.

Based on USDA FSIS's "Foodborne Illness and Disease" page, which FSIS lists as last updated February 7, 2025. I read it October 18, 2026. This is general information, not medical advice.