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Science Paper Calls for Rapid, Pre-emptive Slaughter Called "Ring Culling" to Combat Foot-and-Mouth Disease


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EMBARGOED FOR RELEASE
2 p.m. U.S. Eastern Time
8pm British Summer Time
Thursday, 12 April 2001

Research published 13 April by the journal, Science, endorses the rapid, pre-emptive slaughtering of livestock that may be infected with foot-and-mouth disease (FMD) as the best way to slow the epidemic.

"Ring culling," the pre-emptive slaughter of all animals on farms bordering infection sites, dramatically reduces the spread of disease, scientists at Londons Imperial College School of Medicine reported.

Aggressive ring culling would help prevent the epidemic from spreading beyond the 45,000 farms within the areas currently classified as affected, said Neil Ferguson, Christl Donnelly, and Roy Anderson, whose research is based on data provided by Britains Ministry of Agriculture, Fisheries, and Food (MAFF). If it isnt stopped, FMD will ultimately threaten farms throughout Great Britain, they said.

"Extensive culling is sadly the only option for controlling the current British epidemic, and it is essential that the control measures now in place are maintained during the long decay phase of the epidemic (several months) to ensure eradication," the authors wrote in Science.

Fergusons team used a mathematical model to calculate the potential for disease transmission, given different scenarios. Primary conclusions presented in the Science paper were as follows:

  • The faster that animals are slaughtered following the report of a suspected infection, the bigger the reduction of the epidemic.
  • Even when infected animals are slaughtered within 24 hours after symptoms appear, some 30 percent of all U.K. farms will be affected by FMD over the months-long course of the epidemicunless pre-emptive ring culling is also implemented. Within the heavily affected area of Cumbria, Dumfries and Galloway (CDG), some 79 percent of farms would be affected throughout the epidemic, assuming no ring culling.
  • An even more aggressive approachslaughtering sick animals within 24 hours, followed by ring culling over a 1.5-kilometer area within 48 hourswould protect many more farms. If such drastic measures were implemented consistently, only 16 percent of British farms (53 percent of farms within the badly affected CDG region) would be culled over the course of the epidemic.
  • Vaccinating surviving animals within a 3-kilometer radius of an infection site further reduces the number of farms affected by the epidemic.

First reported in Great Britain in February this year, FMD infects cloven-footed mammals including cattle, sheep, goats, and pigs. Adult animals may survive FMD with permanently reduced weight or milk yield, but the disease can kill the young. The epidemic is concentrated in Great Britain, but outbreaks have been reported in Ireland, France, and The Netherlands.

Logistical difficulties in processing large numbers of animals, and significant delays between reporting cases and culling of farms, are hindering efforts to fight FMD, the authors note. Restricting the movement of people and animals has helped to lower the incidence of infections that occur over a 9-kilometer distance, from 38 percent to 12 percent.

By 3 April, some 631,000 animals had been slaughtered, compared with 440,000 during the last FMD epidemic, in 1967. The latest outbreak, now believed to be approaching its peak, is expected to continue through the summer, scientists said.

-ends-

Dr Neil Ferguson - 020 7594 3296 - email: neil.ferguson@imperial.ac.uk

Imperial College Press Office - 020 7594 6701/2 - mobile: 07803 886248

[This News Release was written and distributed by the AAAS News and Information Office and is reproduced with permission]

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