A micro-organism, such as a bacterium, virus or parasite, that can cause disease when it contaminates food.
Pathogens cause illness and usually do not change how food looks or smells. Spoilage organisms make food deteriorate in appearance, texture or odour but are not necessarily harmful. Food can be spoiled without being unsafe, or unsafe without being spoiled.
No. Pathogens are microscopic and often leave no visible or smell clues. This is why food safety relies on controlling conditions like temperature and hygiene rather than judging by appearance.
Most grow very slowly or stop below 5 degrees Celsius, which is why refrigeration is a key control. However, Listeria monocytogenes can still grow slowly at fridge temperatures, so refrigeration slows but does not always stop it.
Cooking to safe core temperatures kills most vegetative bacteria and viruses, but some bacteria form heat-resistant spores and some produce toxins that survive cooking. Preventing growth is therefore just as important as cooking.
Common food-safety pathogens include Salmonella, Campylobacter, Listeria monocytogenes, certain E. coli strains, Staphylococcus aureus and norovirus. Each has different sources, growth conditions and risks.