Due to climate change, global mean temperature continues to rise. The hot and humid weather in summer favours the growth of various dangerous microorganisms including Vibrio cholerae, which naturally presents in seawater. Sporadic cases of cholera were reported in Hong Kong in recent years. Of the three reported cases last year, two occurred in August.

The incubation period of cholera is usually two to three days and the symptoms include severe diarrhoea, vomiting and dehydration. Delay in treatment may result in death. As Vibrio cholerae is naturally present in seawater, seafood may be contaminated. Hence, consumption of raw or undercooked food that has been contaminated by the bacteria may lead to cholera infection. Also, people may get infected when they accidentally take water or food that has been contaminated with faeces or vomitus of a patient or a carrier.

In order to prevent foodborne diseases, the World Health Organization has advised us to follow the 5 Keys to Food Safety, i.e. choose, clean, separate, cook and safe temperature. Always apply these 5 Keys when you buy, store, prepare and cook food, and you can easily protect yourself against cholera .

First, choose wisely when buying raw materials. Only patronise licensed food premises. Pay attention to the hygienic condition of food premises. Never buy food from unlicensed food premises or illegal hawkers. Buy only those shellfish that are fresh, with intact shell and free from abnormal odour.

Keep our hands and utensils clean. Wash all utensils with hot water and detergent before and after use (especially after handling seafood). Also, wash hands thoroughly with liquid soap and warm water before and after preparing food, after going to toilet and handling rubbish. Take extra care when handling seafood. Clean seafood thoroughly and scrub the shell, preferably with the viscera and shell of shellfish removed.

When preparing food, separate raw food from cooked food to prevent cross contamination. Also, use separate utensils and cutting boards to handle raw and cooked or ready-to-eat food (e.g. sashimi). Similarly, cooked and ready-to-eat foods that are properly wrapped should be placed on the upper compartment of the refrigerator so as to separate them from raw food.

As one of the 5 Keys to Food Safety, cook food thoroughly before eating. Vibrio cholerae can be destroyed by high temperature during cooking. Make sure that the core temperature of food reaches at least 75 ℃. Cook shellfish until the shell open and then further cook for three to five minutes. Shellfish without shell should be cooked for three minutes after the water boils. Also, boil water before drinking.

Keeping food at safe temperature is an important key point that one must remember. Cover leftovers and put them in a refrigerator that is kept at or below 4 ℃. Reheat leftovers thoroughly before eating.

To enjoy food safely in summer months, follow the 5 Keys to Food Safety.