The purpose of the research reported here was to provide assessments of the economic impacts of some 35 diseases affecting farm animals in Great Britain by means of a series of livestock disease economic spreadsheet models. Such assessments are required to support DEFRA policy decisions concerning livestock disease control and research priorities.
The models are able to estimate the ‘direct costs’ (output loss/resource wastage, treatment and prevention costs) of each disease and provide an assessment of the animal welfare and human health implications. The values of key disease variables within the models are determined from the scientific literature and by means of a survey of experts for each disease. ‘Border prices’ are used to value outputs rather than market prices. ‘Low’, ‘medium’ and ‘high’ ranges of key variables are used within the models to reflect variations in estimates. The ‘medium’ estimates are considered to be the best guides as to the current costs associated with each disease.
The animal welfare implications of each disease are assessed by using the results of an expert survey of the welfare impacts of each disease together with the number of affected livestock to give a welfare score. The human health implications of the zoonoses included in the study are assessed by a similar method and using information on the human health costs (days off work, treatment costs etc. plus cost of preventive measures) associated with disease in livestock.
Results of the models show that: (i) for cattle, mastitis has the highest estimate of direct disease costs associated with it (£180 million/yr) followed by lameness (£54 m/yr) and then BVD (£40 m/yr). Lameness has the highest animal welfare loss, followed by mastitis. In terms of human health, VTEC O157 and salmonellosis are the most important diseases (of those considered) with the human welfare implications of salmonellosis being rated highest. (ii) for sheep, enzootic abortion has the highest direct costs associated with it (£24 m/yr), largely because of the relatively high estimated control costs (£17 m/yr), followed by toxoplasmosis (£12 m/yr) and acute enzootic pneumonia (£12 m/yr of which £9 m/yr are estimated control costs). Orf is rated as having the highest animal welfare loss associated with it, whilst enzootic abortion has the highest level of human health costs (largely because of the high value assumed for the loss of a human foetus). (iii) for pigs, swine influenza has the highest direct costs associated with it (£8 m/yr), followed by enteric disease (£6 m/yr). The animal welfare losses are estimated as highest for swine influenza. (iv) for poultry, direct disease costs are highest for infectious bronchitis (£24 m/yr), but skeletal problems have the highest associated animal welfare loss. Not surprisingly, salmonellosis has the highest human health costs (£98 m/yr) and human welfare loss associated with it.
Analyses of disease control measures suggest that only in the cases of vaccination of cattle for BVD, dry cow therapy for mastitis, vaccination of pigs against enteric disease and vaccination against infectious bronchitis and infectious bursal disease in poultry do the likely benefits of increasing control outweigh the costs. However, there are animal welfare benefits associated with the greater use of all of the disease control measures.
Analyses of the benefits to be derived from successful research show that these could be greatest (in absolute terms) for mastitis and lameness in cattle, orf and toxoplasmosis in sheep, swine influenza in pigs and infectious bronchitis and skeletal problems in poultry.
The models provide a useful basis for further analyses and should be made generally available to both researchers and policy analysts for this purpose. The inclusion of additional diseases to the current suite of models should be considered. National epidemiological surveys are needed to provide appropriate data on economically-important diseases. Research on methods for the measurement/estimation and valuation of animal welfare effects should be further pursued.