SLAUGHTERING large numbers of livestock may be an over-reaction to foot-and-mouth outbreaks, research suggests.<
A study shows that cattle infected with the virus are infectious for about half as long as previously thought.
Cows with foot-and-mouth are only capable of transmitting the disease for 1.7 days, scientists have learned. After this time, immune responses are able to block virus replication.
Dr Mark Woolhouse, from the University of Edinburgh, said: “We now know that there is a window where, if affected cattle are detected and removed from the herd promptly, there may be no need for pre-emptive culling in the immediate area of an infected farm.
“We have an opportunity now to develop new test systems which can detect infected animals earlier and reduce the spread of the disease.”
The research, published in the journal Science, characterised precise incubation and infectious periods for foot-and-mouth.
Diseased “source” cows were studied to see how the virus was transmitted to other uninfected cows. Scientists found that even if the virus can be detected in a cow’s blood sample it does not mean the animal is infectious.
In 28 bids to infect healthy cows with foot-and-mouth-disease virus (FMDV) the researchers only observed eight successful transmissions.
“We have pinned down, very specifically, the relationship between when the animals are infectious with FMDV and when they show clinical signs of the infection,” said Dr Woolhouse.
The researchers said if the disease could be detected 24 hours before the appearance of clinical signs, farmers might have time to remove infectious animals before they spread the virus.
There was an urgent need for tests that could detect the virus in non-symptomatic animals.
“It’s technically and logistically challenging, but our work shows that the potential benefits would be much greater than we’ve previously realised,” said Dr Woolhouse. “So ... we should take a look at the possibilities for detecting FMDV early on.”
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