Listeria monocytogenes is a bacterium commonly found in soil and water. It can be easily destroyed by cooking but can survive and multiply at refrigerator temperature. Although healthy people develop few or no symptoms when infected, Listeria monocytogenes could be dangerous to the susceptible groups including pregnant women, newborns, the elderly and people with low immunity.
There have been reports of listeria infection causing death in people with low immunity or causing miscarriage in pregnant women in different countries and regions including Hong Kong. For those susceptible groups, if they would like to consume salad, the general advice is to prepare their own salad and consume it as soon as possible.
The best way to enjoy home-made salads is to have them fresh and hygienic:
- Buy fresh ingredients without signs of damage from reliable shops.
- Avoid high risk ingredients such as cheese made from raw milk and prepackaged ready-to-eat vegetables that may be contaminated with Listeria monocytogenes.
- Wash all vegetables and fruits thoroughly under running water before eating, cutting or cooking, including those produce which would be peeled before consumption. When washing firm produce, such as melons and cucumbers, scrub them with a clean produce brush and dry with a clean cloth or paper towel before preparation.
- Cook eggs, poultry, meat and seafood thoroughly.
- Consume the freshly made salad immediately.