Symptoms usually develop between 12 and 36 hours after ingestion, causing pain, diarrhoea, fever and vomiting which can last for 6 days or more. Although Listeria is widespread in the environment, it is only in recent years that the public have become aware of this organism. It has been involved in cases of food poisoning from the ingestion of affected milk, vegetables, meats, soft cheeses, ice cream and seafood. Listeria monocytogenes is the most significant species and can grow at refrigerator temperatures. Yeasts and Moulds Yeasts do not cause food poisoning, but some types are capable of causing food spoilage.
Moulds can produce mycotoxins, some of which can affect man adversely.
Mould spores can be carried by the wind, and hence can have easy entry to a factory. They do not multiply in water, but are more resistant to sanitation and heat than E. coli and therefore persist longer. The presence of faecal streptococci always acts as an indicator of faecal contamination. Bacillus cereus Bacillus cereus occurs in stools and is common in soil. Hence, foods such as rice, cereals and spices often contain this organism as can milk from cattle with mastitis.