Causes of Food Poisoning
The causes of food poisoning stem from consuming food or drink contaminated by harmful microorganisms or toxins. Food poisoning can result from poor hygiene, unsafe food storage, or undercooked products. In some cases, even clean-looking or well-prepared meals can harbour invisible threats.
Bacterial Infections
Bacteria are among the most common causes:
Salmonella – found in raw eggs, undercooked poultry, and unpasteurised milk
E. coli – often linked to undercooked mince, contaminated water, and raw vegetables
Listeria – found in soft cheeses, deli meats, and unpasteurised dairy products
Campylobacter – common in raw or undercooked chicken and contaminated water
Symptoms can appear within hours or up to several days, depending on the bacteria.
Viral Infections
Norovirus – extremely contagious; spreads through contaminated food, water, or surfaces
Hepatitis A – can be transmitted via infected food handlers or contaminated shellfish
Rotavirus – mainly affects young children, often through unwashed hands or shared items
These viruses often spread quickly in schools, hospitals, and care homes.
Parasites
Giardia and Cryptosporidium – found in untreated water or contaminated produce
Toxoplasma – linked to undercooked meat and cat faeces
Parasitic infections are more common in rural or developing regions, but cases can occur globally
Toxins and Chemicals
Staphylococcus aureus – produces toxins if food is left unrefrigerated
Clostridium botulinum – a rare but dangerous toxin found in improperly canned foods
Chemical contamination – includes pesticides or cleaning agents accidentally introduced into food
Risky Foods
Undercooked meat, raw seafood, and unpasteurised milk
Leafy greens and salad mixes, if not washed thoroughly
Leftovers stored too long or not reheated properly
Street food or buffets, where temperature control is poor
Causes of Food Poisoning
Understanding the causes of food poisoning empowers individuals and businesses to handle food safely and reduce the risk of illness.
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