LONDON — Faulty drains, construction work, heavy rain and vehicle movements at an animal health facility where workers handled live viruses probably led to an outbreak of foot-and-mouth disease in southern England, according to an official report Friday.
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The report was released as the government declared Surrey county, where the outbreak was detected Aug. 3, to be free of the disease. The outbreak led to Britain slaughtering about 600 animals and suspending exports of livestock, meat and milk products for nearly three weeks.
Two reports focused on a site at Pirbright, England, shared by the government-funded Institute for Animal Health, a diagnostic laboratory, and Merial Animal Health, a British unit of the U.S.-French pharmaceutical firm Merial Ltd.
The laboratory uses live viruses for research, and Merial uses the viruses to produce vaccines. Investigators were unable to determine whether the virus originated in the government laboratory or at Merial’s vaccine factory.
“It is now pretty clear that the outbreak originated at Pirbright but it isn’t possible to pinpoint the exact source,” said Geoffrey Podger, chief executive of the Health and Safety Executive.
Podger said inspection of the site at Pirbright, 30 miles southwest of London, showed long-standing damage to effluent pipework.
“It was absolutely essential that this pipework was fully contained, and it was not,” he said.
Foot-and-mouth disease affects cloven-hoofed animals including cows, sheep, pigs and goats. It does not infect humans, but its appearance on farms can have a major economic impact.
An epidemic in 2001 led to the slaughter of 7 million animals and damaged Britain’s economy by shutting its meat out of world markets for months.
Podger said investigators found that live viruses were expected to enter the drainage system, but the system was designed for the pathogens to be killed in a treatment facility.
“We judged it likely that waste water containing the live virus, having entered the drainage pipework, then leaked out and contaminated the surrounding soil,” he said, citing evidence of cracked pipes, tree roots breaching pipework and unsealed manholes.
“We also believe that excessive rainfall in July may have increased the potential for virus release from the drain,” Podger said.
“Vehicles associated with ongoing construction work had relatively unrestricted access to the site,” he added.
“In our opinion, these construction activities — very near to the effluent drainage system — are likely to have caused disturbance and movement of soil in a way that contaminated some of the vehicles with the live virus.”
Some of those vehicles used a road that ran by the farm where the outbreak was discovered, he said.
In a separate report, professor Brian Spratt said concern centered on “the old, poorly maintained and defective effluent system that is shared by the two very different types of facility at the Pirbright site.”
“There had been concern for several years that the effluent pipes were old and needed replacing,” Spratt’s report said, but the government, the laboratory and Merial had not agreed on funding for improvements.
He said the “poor state of the (Institute of Animal Health) laboratories, and the effluent pipes, indicates that adequate funding has not been available to ensure the highest standards of safety ... at this aging facility.”
Spratt said there was “some evidence of complacency about safety” at the Institute of Animal Health laboratory, which is due to be replaced by a new facility in 2012.
Environment Secretary Hilary Benn said the government would take “every possible precaution” to prevent a recurrence.
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