Salmonella is a bacteria that lives inside the gut of many farm animals and can affect meat, eggs, poultry and milk. Other foods such as vegetables, shellfish and fruit can also become contaminated if they come into contact with manure in the soil or sewage in the water.
Salmonella is very easy to transfer, therefore if raw and cooked foods are stored together the risk of spreading the bacteria is highly increased. Other animals such as reptiles can also carry the bacteria and occasionally even dogs, cats and rodents.
Salmonella can be spread from person to person by poor hygiene, by failing to wash your hands properly after going to the toilet, or after handling contaminated food.