Escherichia coli O157:H7; an economic assessment of an outbreak

The aim of the study was to assess the impact of an outbreak of Escherichia coli O157:H7 that occurred in 1994 in a rural community, with a population of approximately 107,000, to the west of Edinburgh.

The impact of the outbreak was assessed during the acute phase of the illness and in the subsequent 12 months. The method involved three surveys of confirmed cases using general practice notes, hospital records and interviews with cases. Key persons involved in the investigation and control of the outbreak were also interviewed. The impact of the illness on cases and their families was estimated and the resources used to treat cases and to control the outbreak were costed and long-term costs projected.

There were 71 cases whose ages ranged from 7 months to 84 years. The mortality rate was 1.4 per hundred cases. There were 10 cases of haemolytic uraemic syndrome (HUS) and one case of thrombotic thrombocytopenia purpura (TTP). Two children were on long-term dialysis. Co-morbidity involving the immune system was associated with hospital admission. The illness lasted on average 6.9 weeks. Twenty-six per cent of cases reported symptoms 12 months later. The average cost per HUS case was 62,353 pound sterlings, the TTP case cost 21,422 pound sterlings, non-HUS and non-TTP cases cost 1,030 pound sterlings. The costs of investigating and controlling the outbreak were 171,848 pound sterlings. The costs of cases projected over 30 years were 11.9 million pound sterlings, or 168,032 pound sterlings per case.

The impact on the health of cases was considerable and the costs were high. Every effort should be made to prevent the disease and to identify and control outbreaks quickly.