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Research suggests pre-emptive mass culling of cattle may not be necessary The mass culling of cattle and funeral pyres that blighted the countryside during the 2001 foot and mouth epidemic may not be needed if the disease comes back, according to scientists who have shown that it is detectable in cattle up to 24 hours before they become infectious. This could provide a window to quarantine infected animals and stop the spread of the disease to neighbouring farms. The researchers also found that cattle infected with the foot and mouth virus remained infectious for an average of only 1.7 days, much less than previously thought. At least 6 million animals were culled during the 2001 outbreak, most of them sheep. The Royal Society estimated losses of about £3.1bn to agriculture and the food chain, and about £2.5bn was spent by the government in compensation for slaughtered animals and payments for disposal and cleaning up. There were only 2,030 confirmed infections, but millions more animals were culled – killed pre-emptively because they lived near infected farms. Had government advisers understood more about the disease, it might have been possible to control it without mass culling. “The reason those animals were culled was because they may already have been infected by the time we knew they were at risk,” said Mark Woolhouse of the Centre for Immunity, Infection and Evolution at the University of Edinburgh. “What this suggests is a window where we can detect animals before that has happened so there’s no need, in that case, for the pre-emptive culling.” Mark Woolhouse of the Centre for Immunity, Infection and Evolution at the University of Edinburgh, said: Woolhouse added: The new research is published in the journal , shows there here is this short window, a day or two, where we can tell a cow is infected with foot and mouth disease but it’sthe disease can be detected but the animal not yet infectious to other cows – even under ideal conditions it doesn’t transmit the virus. . “If we could detect and remove animals in that window of opportunity, then they won’t have the chance to infect to infect other animals.” The new research is published in the journal Science . For the study, a team led by Bryan Charleston of the Institute for Animal Health in Pirbright infected cows with foot and mouth disease in the laboratory and then watched how the virus spread to uninfected cows. The time from infection to the onset of clinical signs was approximately four days. The animals became infectious at around the same time and stayed that way for, on average, 1.7 days. Until now, scientists had thought that cattle became infectious up to four days before they showed clinical signs, and then remained infectious for up to four to eight days afterwards. But Charleston also found there was a point where virus detection was possible before the animals became infectious. “After an animal becomes infected, you can start to detect virus in blood and in nasal samples approximately two to three days later, that’s before they show clinical signs and before they are able to transmit the virus,” he said. The government’s chief vet, Nigel Gibbens, said: “While these types of tests aren’t currently practical for use on the ground during an outbreak, we are continuing to fund their development and are working with the Institute of Animal Health so the best possible tests and equipment is available. Quick reporting of suspect cases of the disease by farmers and veterinarians and selective culling of animals, with vaccination where that can make an effective contribution to control, remain the best way of stopping this disease.” The 24-hour window allows farmers and scientists to isolate and cull the infected herd before they can spread the infection to neighbouring herds. “It’s not the animals that are infected that are saved, it’s the ones they might have put at risk, all the animals in the next-door farms,” said Woolhouse. Joe Brownlie , emeritus professor of veterinary pathology at the Royal Veterinary College, said the pre-emptive culling policy in 2001 was “quite draconian” and the new research would prevent the death of large numbers of animals in future. “Many of us have had difficult times justifying and living with what happened. This is exciting and very important science.” A spokesperson for the National Farmers Union described the study as an “important development”. “The outbreaks of foot and mouth disease in 2001 and 2007 show just how devastating this disease is for farm businesses and the wider rural economy. “It’s clear that the researchers are some way from developing a reliable on-farm test and the protocols that may be needed in its application. Nevertheless, this is a valuable development that could help control FMDV spread during future outbreaks.” Translating the research into a practical technology for the field will take some time. “This we can do in the laboratory, we can detect infections before the animals are infectious – it is going to be a significant challenge to do that in the field during an epidemic,” said Woolhouse. “As a result of the work we’re reporting today, we know that such an approach could be much more effective than we’ve realised before, so this is definitely an avenue we should be pursuing.” Apart from the 2001 foot and mouth epidemic, a smaller outbreak of the disease in 2007 was localised to a farm near Guildford, when 60 animals tested positive. Foot and mouth Rural affairs Alok Jha guardian.co.uk