Risk factors for transmission of foot-and-mouth disease during an outbreak in southern England in 2007

During an outbreak of foot-and-mouth disease (FMD) in southern England in 2007, a case-control study was conducted to identify risk factors for infection and to investigate the relative impact of risk factors on transmission between the infected farms. Seven of the eight case farms in the outbreak and 22 control farms participated. Data were collected via questionnaires and subjected to comparative statistical analysis. Case farms were further classified as primary or secondary according to the likely source of infection during the study. On primary case farms, it was plausible that infection had been introduced directly from the original source. On secondary case farms, FMD infection was more likely to have originated from another infected premises. Calving occurred more frequently on case farms than on control farms during the risk period, and the two primary case farms had a larger proportion of youngstock than the other farms. Secondary case farms (n=5) had a higher composite environmental risk score and a lower biosecurity score than control farms.