As temperatures rise, so does the risk of food poisoning — and it can happen even when your food looks and smells perfectly fine.
Here are some of the most dangerous bacteria and viruses that could be hiding in your meals, and what you can do to stay safe.
Listeria

Listeria is the third leading cause of death from foodborne illness in the U.S.
It thrives in moist environments like factory drains and is commonly found in raw milk, hot dogs, smoked seafood, and salads.
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Particularly dangerous for pregnant women, the elderly, and those with weakened immune systems, it can lead to meningitis, miscarriage, or stillbirth.
Heating food above 165°F (74°C) and using diluted bleach on surfaces can kill the bacteria.
Norovirus

Highly contagious and fast-spreading, norovirus is notorious for causing outbreaks in crowded places like schools, cruise ships, and nursing homes.
It spreads through direct contact, contaminated food or surfaces — and even through airborne particles from vomiting.
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Symptoms hit within 12 to 48 hours and include intense diarrhea, nausea, cramps, and fever. It can remain infectious on surfaces for weeks.
Salmonella

Salmonella is a well-known but still common foodborne threat.
Often found in undercooked meat, eggs, and raw vegetables, it causes symptoms within 6 hours to 6 days: fever, stomach cramps, and sometimes bloody diarrhea.
It’s especially dangerous for young children and people with weakened immune systems. Good hygiene and thorough cooking are key to prevention.
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Campylobacter

Campylobacter infections occur much like salmonella — through undercooked meat and contaminated produce.
It can lead to vomiting, diarrhea, and fever. Often, people get infected at home due to poor food handling.
Safe food practices and clean preparation areas are crucial to staying safe.
E. Coli

While some E. Coli strains help digest food, others are dangerous and can lead to kidney failure and even death.
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The harmful strains typically spread through contaminated food, animal contact, or poor handwashing.
Symptoms include severe stomach pain, loss of appetite, and bloody diarrhea. Proper hygiene and safe cooking practices are essential defenses.
Left-out food

Food left at room temperature for more than two hours becomes a playground for bacteria like listeria and salmonella.
Always refrigerate leftovers promptly and never leave meals sitting out. Time and temperature are crucial when it comes to food safety.
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Cross-contamination

When juices from raw meat touch vegetables, or the same knife is used for salad and chicken without washing, bacteria spread fast.
Always use separate cutting boards and clean utensils thoroughly to prevent contamination.
Raw milk and unpasteurized products

Though trendy in some circles, raw milk and unpasteurized dairy products can contain listeria, E. Coli, and other harmful microbes.
These are especially dangerous for vulnerable groups. Pasteurization removes most harmful bacteria without affecting nutrition.
Processed meats

Hot dogs, deli meats, and pre-packaged sandwiches are common sources of listeria outbreaks.
Always reheat thoroughly and store them at the correct temperature. Check expiration dates and avoid anything that’s been sitting out too long.
Poor hand hygiene

Many foodborne illnesses stem from one simple mistake: not washing your hands. Norovirus, E. Coli, and salmonella all spread easily through dirty hands.
Wash thoroughly with soap and water for at least 20 seconds — especially after using the bathroom or before handling food.
This article is based on information from National Geographic.