An analysis of quality assurance and zoonoses action plan data from pig herds in the United Kingdom

The Zoonoses Action Plan required that meat juice (MJ) samples from slaughtered pigs were monitored for antibodies against salmonella in amix-ELISA. These results were linked to data, routinely collected by quality assurance schemes to create a dataset, representingmore than 1,500 pig holdings with an average of 30MJ ELISA results per farm. The data was analysed to identify factors associated with salmonella infection, and to indicate potential analytical approaches.Multivariable analysis showed that samples fromfarms in Yorkshire and the Humber, and those that housed finisher pigs on solid flooring,were associated with positive ELISA results.Univariable analysis showed significant regional differences in pigmanagement, and spatial analysis showed high prevalence holdings in Yorkshire and the Humber weremore clustered in space than low prevalence holdings.However, poor data quality precluded analysis ofmany variables, and recording errors in identifiers (e.g. slapmark) caused problems inmatching samples to holdings. If the quality and range of data collected in the schemes could be improved, then the large sample size would ensure sufficient statistical power to identify even weak associations between a broad set of variables and MJ ELISA status,which could help target on-farmcontrolmeasures relevant for the UK pig population.