Reanalysis of the start of the UK 1967 to 1968 foot-and-mouth disease epidemic to calculate airborne transmission probabilities

摘要

A number of studies into the start of the UK 1967/68 foot-and-mouth disease (FMD) epidemic supported the hypothesis that windborne spread played an important role in the initial spread of the virus from Oswestry Shropshire, northeast to the Cheshire plains. Since then, atmospheric dispersion models (ADMs) have been developed that are capable of simulating the spread of FMD virus (FMDV) plumes from an infected source farm using real weather data, and to estimate exposure rates to susceptible livestockat various distances downwind. However, in order to properly evaluate the risk of transmission to these livestock, the dose-response probability of infection for airborne exposure to FMDV must be known. In order to establish this under field exposure conditions, data from historical accounts where airborne transmission is believed to have occurred must be used. Unfortunately, despite the availability of case records from the UK 1967/68 epidemic, the dataset did not include any information on control farms, that is, exposed farms that did not succumb to infection. Without this, probability estimates are difficult to ascertain. This study describes an attempt to calculate the true transmission risk associated with airborne spread of FMDV at the start ofthe 1967/68 FMD epidemic, in the area around the index farm at Oswestry.