The economic and social impact of human salmonellosis in England and Wales: a study of the costs and epidemiology of illness and the benefits of prevention.

This thesis presents a detailed analysis of illness related costs of human salmonellosis In England and Wales, estimated at £263 million (minimum), including intangible costs, in 1988, and explores potential benefits of preventive activities aimed at the poultry industry. To explore trends In reported infection and the factors which may influence those trends, salmonella reporting between 1960 and 1989 was examined. Trends in foodborne Illness were associated with increased reporting of salmonella infection. The factors which contributed to this increase included Intrinsic factors such as the microbiological quality of food, and extrinsic factors such as ambient temperature which may amplify intrinsic effects. Evidence that poultry products were important vehicles of human Illness was supported by trends in infections in animals and poultry, and food consumption patterns. Thus a significant decrease in human infection would result from reduction in poultry contamination. The findings of a unique and detailed survey of 1,482 human salmonella cases, presented in this thesis, indicated tangible costs of illness of £996,350 to £1,091,131. Over a third (E392,822 - £426,887) were costs related to investigation and treatment of cases and over half (E507,555 -E559,401) was production loss associated with sickness related absence from work. The remaining costs Identified represented important costs to affected Individuals and their families. Additional intangible costs of £1.57 million to £5.07 million were ascribed to value of lives lost and to pain and suffering estimates. Extrapolation of costs, utilizing an index of severity developed for this study and categorisation of cases by level of treatment demanded, indicated national, tangible, costs of £231 million to £331 million; additional intangible costs were £32 million to £119 million). The cost-effectiveness of limiting these totals was explored by two approaches. Cost reduction by changes in cases management (eg. reducing faecal specimens tested and time off work) indicated small potential savings. However, substantial benefits were indicated by cost-benefit analysis of preventive activities including irradiation of poultry carcasses and use of competitive exclusion methods in poultry rearing.