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Bacterial Food Poisoning: A Serious Threat for the Elderly

Weaker immune system of the elderly puts them at risk of serious bacterial food poisoning

Toast served with half-boiled eggs is a popular Singaporean breakfast, but for elderly Singaporeans and those with weak immune systems, it may be prudent to avoid eating undercooked eggs which put you at risk of serious bacterial food poisoning caused by the Salmonella bacteria.

According to the Ministry of Health’s Weekly Infectious Disease Bulletin, Salmonella is the leading cause of food poisoning in Singapore with 1,480 cases reported in 2010 and 1,383 cases in 2011. It can be particularly harmful for the elderly.

“Bacterial food poisoning caused by Salmonella or another bacteria known as Listeria can become very serious in the elderly because the bacteria may spread to other organs,” says Dr Limin Wijaya, Consultant at the Department of Infectious Diseases, Singapore General Hospital (SGH), a member of the SingHealth group.

“The weaker immune system of the elderly makes them more vulnerable to developing serious bacterial infections and complications,” adds Dr Wijaya.


Causes of Salmonella food poisoning

Most food poisoning incidents are a result of mishandling of food. The Salmonella bacteria can spread through food contaminated by animal or human waste. Meat, milk, eggs and poultry are common breeding grounds for Salmonella bacteria. It gets to other food by cross-contamination from contact with raw food, utensils or equipments.

Fruits and vegetables contaminated with faeces in the soil or water can also cause Salmonella food poisoning.

Food handlers who do not wash their hands thoroughly after going to the toilet may cause food to be contaminated with Salmonella.


Causes of Listeria bacterial food poisoning

Listeriosis is another type of food poisoning caused by a bacterium known as Listeria monocytogenes. Listeria bacteria usually spread through raw foods such as soft cheeses, uncooked meats and vegetables, and unpasteurised milk. It may infect ready-to-eat deli meats, hot dogs and luncheon meats.


Symptoms of bacterial food poisoning

Salmonella infections:

  • Nausea and severe diarrhoea (common)
  • 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.


Complications and treatment of Salmonella and Listeria infections

Salmonella can cause infections in the heart, bones or bone marrow; it can also cause meningitis, an inflammation of the membranes covering the brain and spinal cord though this is rare.

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. 


9 tips to prevent bacterial food poisoning

  • 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.


  Source: By Teresa Cheong for Health Xchange, with expert input from the Department of Infectious Diseases, Singapore General Hospital (SGH), a member of the SingHealth group.


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