The public health significance of VTEC O157

Surveillance of human VTEC O157 has been reported in several countries, bas ed on laboratory evidence. The incidence is generally less than 10 per 100 000 (the highest incidence is in children), with regional variations and a marked seasonality. Laboratory selection criteria and reporting have contri buted to, but cannot entirely explain, variations within and between countr ies. Surveillance data and outbreaks in definable cohorts indicate that the spectrum of illness ranges from diarrhoea through acute bloody diarrhoea, with about 5% of cases developing haemolytic uraemic syndrome; less than 50 % of patients report frank blood in their stools. Studies of sporadic cases have associated illness with beef products (particularly if undercooked an d eaten outside the home), cooked sliced meat meals and contact with a hous ehold member with diarrhoea. Outbreaks have been attributed to contaminated foods (including beefburgers) and water, animal contact and person-to-pers on spread. Secondary transmission by the primary case in a household is of particular concern, and household transmission has been estimated at 4%, wi th patients excreting for around 10 days following onset. Recommendations f or control have highlighted measures on farms, in slaughterhouses, retail a nd catering food premises, and in the home.