Mould
Mould is another type of pathogen, in the form of microscopic fungi that live on plant or animal matter. This is the furry growth you may see on soft fruits such as strawberries, for example, which spoil quickly, but which can grow on pretty much any food.
Moulds can cause allergic reactions and breathing problems, and they produce spores that can spread through air or water to other foods. They have the potential to be very hazardous to health, e.g. one type, Aspergillus, which grows on peanuts and peanut products, produces a group of toxins called aflatoxins, which can cause liver cancer.