Prevention of Foodborne illness in the High Risk Groups
What is foodborne illness? Foodborne illness refers to any illness that is related to food ingestion. It is commonly caused by bacterial pathogens such as Salmonella spp. However, certain foodborne pathogens may also gain entry into our body through skin cuts or abrasion during the handling or preparation of food, e.g. Vibrio vulnificus. Persons with foodborne illness generally present with gastrointestinal symptoms such as abdominal pain, vomiting and diarrhea. Sometimes, systemic symptoms like fever may also occur. Healthy persons generally experience mild symptoms when they get these infections. However, some persons are more susceptible to these infections and may have unusually severe illness.

The high risk groups The elderly, infants and young children, pregnant women, and immunocompromised persons are among the so called "high risk groups". These persons are either more susceptible to infection caused by a particular pathogen or they are more likely to develop severe disease or complications as a result of the infection.

The elderly Elderly people are more susceptible to foodborne illness and associated complications because of the decline in the function of the immune system and the decrease in stomach acid secretion. For example, elderly people infected with Salmonella are at increased risk of complications and death.

Infants and young children They are especially vulnerable to foodborne illness because their immune systems are not fully developed and their stomachs also produce less acid. For example, infants and young children are more likely to develop complications arising from infection with Escherichia coli 0157:H7.

Pregnant women Hormonal changes during pregnancy can have an effect on the mother's immune system that may lead to an increased susceptibility to certain infections, notably listeriosis. Listeria monocytogenes infection can lead to premature delivery, miscarriage, stillbirth or neonatal mortality.

Immunocompromised persons The immune systems of these persons are depressed due to underlying medical diseases or drug therapy. For example, persons with diabetes mellitus or chronic liver diseases are known to have a higher risk of death when they are infected with Vibrio vulnificus.

Table 1: Common diseases or conditions that render a person immunocompromised

• Liver cirrhosis and other chronic liver diseases
• Chronic renal diseases
• Diabetes mellitus
• Human immunodeficiency virus (HIV) infection
• Malignancies
• Malnutrition
• Patients on long-term steroid or immunosuppressive chemotherapy for underlying diseases, e.g. systemic lupus erythematosus (SLE) patients, organ transplant recipients
• Patients with their spleens removed

Table 2: Associations between the high risk groups and specific pathogens

Ways to prevent getting these infections
General precautions

• Always wash hands, chopping boards, containers and cooking utensils with warm water and soap before and after contact with raw food
• Handle and store raw food and cooked food separately to avoid cross contamination
• Never leave perishable food out of refrigerator for longer than 2 hours. Leftovers should be refrigerated at 4°C or below as soon as possible and reheated until they are steaming hot before consumption.

Table 3: Pathogen-specific precautions

Centre for Health Protection of the Department of Health Website www.chp.gov.hk
24-Hour Health Education Hotline of the Department of Health 2833 0111