Salmonella infections:

• Nausea and severe diarrhoea
• Watery stools
• Vomiting
• High fever
• Stomach cramps
• Dehydration (e.g. dry mouth, reduced urine output)

Listeria infections:

• Muscle aches
• Fever
• Nausea and diarrhoea (less common)

More serious symptoms include confusion, loss of balance, shaking or convulsions, headaches and stiff neck if the Listeria bacteria infect the nervous system.

Salmonella can cause infections in the heart, bones or bone marrow; it can also cause an inflammation of the membranes covering the brain and spinal cord though this is rare, says Dr Limin Wijaya​, Senior Consultant at the Department of Infectious Diseases, Singapore General Hospital (SGH), a member of the SingHealth group.

For the elderly with weak immune systems, the Listeria bacteria may invade the central nervous system and cause bacterial meningitis which is serious and potentially life threatening.

Salmonella infections usually clear up on their own within four to seven days without treatment in normal, healthy people, but the elderly may take longer to recover. Antibiotics are prescribed for severe infections that have spread beyond the intestines.

Healthy individuals rarely become ill from Listeria but this infection can be fatal in certain groups of individuals such as pregnant women and the elderly.

• Keep leftover foods refrigerated. Heat them until they are steaming hot before eating.
• Re-heat deli meats, canned luncheon meats or hot dogs until they are steaming hot.
• Cook raw meats thoroughly.
• Avoid eating raw foods such as raw or undercooked eggs.
• Wash your hands thoroughly with soap and water after using the bathroom and before preparing food.
• Don't drink unpasteurised milk.
• Wash raw vegetables and fruits thoroughly.
• Keep knives used to cut meats separately from those used to cut vegetables.
• Keep cooked food separate from raw food.

"Bacterial food poisoning should not be taken lightly in the elderly. If you experience persistent diarrhoea and fever, get medical help immediately," advises Dr Wijaya.

Ref. T12