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Children and microbial foodborne illness

The incidents of salmonellosis discussed above highlight the fact that the risk of some foodborne illnesses is relatively higher for children than for most other groups in the community.

A major review some years ago (International Journal of Food Microbiology 30 1996 113-123) identified four demographic groups to be at greater risk of foodborne illness. These were the very young, the elderly, pregnant women and the immunocompromised. The review also noted that the case fatality ratio for foodborne bacterial gastroenteritis outbreaks in nursing homes was 10 times greater than for the general population. Obviously special care needs to be taken with food hygiene in these circumstances.

Children also deserve added protection in the study and prevention of foodborne illness. Children's immune systems are not fully developed increasing the risk of illness including foodborne illness. A child's lower weight probably means it requires a smaller number of pathogens to make a child sick than it would a healthy adult (Food Review 24 2001 32-37 [fulltext]). We have commented previously on the low infective dose for salmonellae in children when ingested in certain foods (see, for example, Food Safety and Hygiene August 1998).

In the Food Review article cited above, the author who is with the Economic Research Service of the United States Department of Agriculture, uses US data to demonstrate that infants (less than 1 year old) have the highest risk of contracting salmonellosis while children under 10 years are the second highest risk group. While most salmonellosis cases are relatively mild, deaths do occur particularly in the high risk groups.

The enterohaemorrhagic Escherichia coli (EHEC) and their link to food became well known to the public in the early 1990s with serious incidents in the US and the UK. In the US, over 700 people, primarily children, became ill from outbreaks caused by improperly cooked hamburgers. The infecting organism was E. coli 0157:H7 and four children died. Since then outbreaks have been associated with a wide range of foods.

In Australia, a serious outbreak of foodborne illness occurred in 1994-95 from another strain of EHEC, E. coli 0111 in an uncooked, fermented sausage product which had been improperly processed. In this incident, a four year old girl died and 23 children were hospitalised. At least 150 cases of illness from the same cause were identified.

The enterohaemorrhagic E. coli cause illness through the toxins they produce. Acute illness is accompanied by abdominal cramps, vomiting, diarrhoea and sometimes fever. Infection can sometimes result in haemorrhagic colitis and a small percentage of cases progress to develop haemolytic uremic syndrome (HUS). HUS is a life threatening condition characterised by red blood cell destruction, kidney failure and neurological complications. People who develop chronic kidney failure may require lifelong dialysis or a kidney transplant.

Several studies have identified age less than 4 or 5 years as a risk factor for HUS and this is supported by infection rates recorded in the US (Food Review 24 2001 32-37).

Children have very limited control over food safety risks because their food is usually prepared by others. The positive side of this discussion is that many cases of foodborne illness including those caused by salmonellae and enterohaemorrhagic E. coli can be prevented by correct food hygiene and food handling practices.

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Prepared by Keith Richardson and Rachel Jackson
Food Science Australia
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