Learn About Salmonella


       Salmonella (Salmonella spp.) is one of the most common causative agents of foodborne disease. The bacteria are widely distributed in domestic and wild animals, prevalent in food animals (e.g. poultry, pigs and cattle), animal offal and their products. Over 2,500 serotypes of Salmonella have been identified to date, in which more than 200 serotypes are human pathogens.


Health impact

       The onset of Salmonellosis symptoms occurs 6 to 72 hours (usually 12 to 36 hours) after infection and the illness lasts 2 to 7 days. The symptoms are relatively mild, like acute fever, abdominal pains, diarrhoea, nausea, and sometimes vomiting. In most cases, patients will make a recovery without specific treatment. However, in some cases, particularly in young children and elderly patients, the associated dehydration can become severe and life-threatening.


Mode of transmission

       It includes consumption of food and water contaminated by animal or human faeces. The kinds of food more susceptible to contamination include raw or undercooked chicken eggs/egg-based products, milk/dairy products, meat/meat products and vegetables contaminated by manure. Improper storage of food may cause rapid multiplication of the bacteria at high temperature, which prompts the spread. Farm animals become vectors of Salmonella upon consumption of contaminated feed and spread the bacteria during their breeding and slaughtering process. Faecal-oral route is a major means of person-to-person transmission. In cases of diarrhoea, the bacteria present in patients’ faeces are highly infectious than those of asymptomatic carriers.


How to Avoid Salmonella Infection?


Advice to the Public:

1. Choose and purchase smartly, and ensure that water sources and food ingredients for cooking are safe.

  • Purchase food from licensed and reputable shops. Never patronise unlicensed hawkers;
  • Check if the food packaging is intact and the food’s expiry date is not due.

2. Cautious handling: Handle raw and cooked food separately to avoid cross-contamination.

  • Wash hands thoroughly before and after handling food;
  • When purchasing, place raw food separately from other food items;
  • Store raw and cooked food separately. Remember to place “cooked food above raw food” in the refrigerator;
  • Use two sets of utensils for handling raw and cooked food to avoid cross-contamination;
  • Thaw frozen food in the refrigerator or under running water;
  • Refrigerators should be cleaned and defrosted regularly. The internal temperature should be maintained at below 5°C.

3. Cooking: Food must be thoroughly cooked.

  • Food must be thoroughly washed, cooked and eaten as soon as possible after preparation;
  • Never reheat cooked food more than once. The leftover food must be thoroughly reheated before consumption and leftovers of reheated food should be discarded.

 Advice to the Food Trade:

  1. Make sure that the sources of goods are reliable and purchase them from reputable suppliers;
  2. Frequent hand washing and pay attention to food, environmental and staff hygiene to avoid cross-contamination;
  3. Cook food thoroughly during the preparation process;
  4. Cover food with plastic wrap before storage in refrigerator. Thoroughly reheat the refrigerated food before consumption;
  5. Prepared food should be kept at a proper temperature (cold food at below 5°C and hot food at above 60°C) to ensure food safety;
  6. Food-handlers showing symptoms of vomiting, diarrhoea or fever should seek medical attention promptly to prevent the spread of disease to others during food preparation;
  7. Regular vector control to get rid of pests and rodents. All trash bins must be covered and the trash must be removed at regular intervals.


       Safe food for safe consumption, combined efforts of Government, Food Industry and Public are required!