The Hampshire epidemic of foot-and-mouth disease, 1967

Abstract

SUMMARYAn analysis was made of the spread of foot-and-mouth disease during the epidemic in Hampshire in January and February 1967. To explain the pattern of spread, it had to be postulated that virus was present seven days before the first outbreak was reported. It is suggested that the disease occurred initially in pigs fed on infected meat and that the virus was subsequently disseminated from the local abattoir, where the pigs were killed, to four farms by movement of animals, slaughterhouse waste, people or vehicles, and to fifteen by the airborne route. Subsequent spread from these farms was by movement in two instances and by the airborne route in five. The source and route of infection of the last farm in the outbreak were not determined.The risk of spread through movement was associated more with carriage of infected slaughterhouse waste, movement of animals, people or vehicles carrying animals than through collection of milk, artificial insemination or movement of other types of vehicles. Outbreaks of disease among pigs gave rise to more secondary spread than outbreaks in cattle. Secondary outbreaks attributed to airborne spread occurred only in ruminants. Most airborne spread was into areas of high livestock density and cattle in the larger herds became infected. Airborne spread could be correlated with wind direction and speed but not with rain. The reduction in the number of outbreaks at the end of the epidemic could be attributed to the elimination of the largest sources of virus, the control of movements and the fact that in all instances except two the wind was blowing virus over towns and out to sea, to areas of low stock density and to areas where animals had been killed.

The survival of foot-and-mouth disease virus in open air conditions

“…The choice of autumn and winter for the investigation was deliberate since this is the time of year when the airborne spread of FMD more usually occurs in temperate countries (Fogedby, Malmquist, Osteen & Johnson, 1960;Hurst, 1968;Smith & Hugh-Jones, 1969;Sellers & Forman, 1973;Primault, 1974). Autumn evenings are the occasions on which temperature inversions tend to occur in the U.K. so that it is likely that higher levels of OAF than observed in the present study may occur.…”

Airborne spread of foot-and-mouth disease – Model intercomparison

“…The 1967 Hampshire, UK outbreak of FMD was selected by IAH/Met Office as being suitable for the workshop; the outbreak had been investigated previously by Sellers and Forman (1973) and Gloster et al (1981) and they concluded that up to sixteen of the farms could have become infected by airborne virus from either Fareham Abattoir Figure 1 gives the locations of the infected premises, together with the locations of the major conurbations in the area, the coastline and an area of high ground (Portsdown Hill -shaded area) to the east of Fareham Abattoir (outbreak no. 9).…”

“…In view of the conclusions drawn by Sellers and Forman (1973) participants were asked to concentrate their efforts on modelling the potential spread of FMD virus from Fareham Abattoir. (Sørensen et al, 2007;Mikkelsen et al 1997;Sørensen et al 2000;Sørensen et al 2001).…”

“…Whilst there are some differences most estimates are within one order of magnitude; this could easily be accounted for by the different assumptions within the model with respect to the rate at which surface material diffuses upward in the atmosphere and choice of input weather data. Secondly, the outbreaks suggested by Sellers and Forman (1973) Table 4 presents the results. All of the outbreaks identified by Sellers and Forman (1973) were assessed as at risk by the models.…”

“…Secondly, the outbreaks suggested by Sellers and Forman (1973) Table 4 presents the results. All of the outbreaks identified by Sellers and Forman (1973) were assessed as at risk by the models. In general there was very good agreement between the models for premises close to the source, but this agreement decreased with distance, as expected, as differences between chosen input weather data become more pronounced.…”