Salmonella food poisoning (salmonellosis) is usually linked to consuming inadequately cooked meats or poultry, other foods contaminated by raw meats and poultry, as well as foods containing raw or undercooked eggs, unpasteurised dairy products such as raw milk or cheeses.
But many other foods have been linked to outbreaks caused by Salmonella including mayonnaise (with raw eggs), fruits and vegetables, salads, milk, unpasteurised fruit juices, nuts, seeds and sprouted seeds. It gets into other foods by cross contamination from contact with raw foods, utensils, equipment and hands.
In Australia, salmonellosis tends to be more prevalent in the warmer, northern parts of the country and eating food that has been kept in the temperature danger zone for too long allowing the bacteria to grow is often the cause of the illness. However, even small numbers of Salmonella can cause foodborne disease. Sensitive individuals such as the elderly, young children and people with low immune systems, are much more likely to become ill after consuming only a small number of cells.
It usually takes 8 to 72 hours for symptoms of salmonellosis to occur, but can take up to a few weeks, so it is not necessarily the last meal you ate that caused it. Salmonella causes a ‘gastro-flu-like’ infection which in most cases lasts about two to five days. However, in some people it can lead to chronic conditions such as Reiter’s Syndrome or reactive arthritis.
Salmonella usually needs to grow to a sizeable population of bacteria to make healthy adults sick. However, in high fat foods like peanut butter, potato crisps and chocolate, and liquids which pass through the stomach quickly, such as unpasteurised juices, the presence of only a few bacteria can cause illness. It can also survive in fairly dry and mildly acidic foods for some time during food storage.
Because Salmonella is a natural resident in the gut of food production animals we should assume that it is in raw animal foods such as meat, poultry, milk and eggs. Vegetable foods can also be contaminated, for example if they come in contact with animal faeces or contaminated water. Most outbreaks occur through cross contamination from raw to cooked food, and contaminated food remaining in the temperature danger zone for too long. If cooking or reheating is inadequate then the bacteria will survive.
If you think you may have salmonella food poisoning you can get medical advice on the Healthdirect website