Foot & Mouth outbreak linked to process failings
1 Oct 2007
Poor maintenance and control procedures allowed virus to transfer from research centre to farmland via waste pipeline. Patrick Raleigh reports
The Health & Safety Executive has linked the recent outbreaks of Foot & Mouth disease at farms in Surrey, to a leak from the Pirbright site, near Guildford. The site is occupied by the UK government-run Institute of Animal Health (IAH) and two private companies; Merial Animal Health Ltd and Stabilitech Ltd.
The virus involved — O1 BFS, which is classified as a SAPO Category 4 pathogen — was a laboratory strain that was being worked on by all three occupants of the Pirbright site, said the HSE's final report into the incident.
The outbreak, which has had a severe impact the entire UK livestock industry, was probably caused by the virus escaping through a leaking underground pipe before being brought to the surface by July's flooding.
In its report, HSE concluded that live strain of virus entered the effluent drainage system from a pipeline between 22 and 26 July. It believes that the pathogen leaked from the buried pipework between the Merial and IAH buildings.
The virus contaminated the surrounding soil either through overflowing of a manhole and/or a leakage around the drainage pipes, said HSE. It is likely, it added, that floodwater spread the virus onto the tyres of vehicles using the site which then transferred it to local farms.??
"The inadequate levels of containment offered by the effluent drainage system represent a breach to the biosecurity arrangements at the Pirbright site," said Dr Paul Logan Pirbright lead investigator.
HSE also expressed concerns about the chemical treatment systems for sterilising liquid waste containing SAPO Category 4 pathogens. These treatments, while reducing the amount of pathogen in the liquid, may not render the liquid completely pathogen-free.
The HSE investigation found other serious deficiencies in the operation of the Surrey site, many of which failed to meet the requirements for handling dangerous biosubstances:
- Laboratory filter arrangements did not allow filters to be tested independently
- Lack of a written standard operating procedures to deal with blockages in the effluent drainage system
- Failure to properly manage contractors working around the effluent drainage system.
"Neither the existing effluent drainage system in use across the Pirbright site nor the record keeping, maintenance and monitoring regimes in place for it are considered to meet the standards required for SAPO Level 4," commented Logan.
Likewise, Keith Plumb, a chartered chemical engineer and biosecurity expert, believes the incident indicates that there were lapses in safety, maintenance and virus handling, in particular the way in which Merial was apparently allowed to transfer untreated effluent from their premises to the IAH.
"A virulent and persistent virus like Foot & Mouth Disease should be destroyed within the same building as it is being handled and not transferred anywhere else, said Plumb, who is also an independent expert for the IChemE.
Best practice in process engineering suggests running the pipe above ground, making leak detection much easier, continued Plumb. "The further layer of protection would be provided by a double pipe system that contained any leaks and this could be backed up by an automatic leak detection system."
A set-up like the one at Pirbright, where an underground pipe transfers harmful liquid from one site to another, can also lead to confusion about who is responsible for maintenance," commented Plumb.
The virus involved — O1 BFS, which is classified as a SAPO Category 4 pathogen — was a laboratory strain that was being worked on by all three occupants of the Pirbright site, said the HSE's final report into the incident.
The outbreak, which has had a severe impact the entire UK livestock industry, was probably caused by the virus escaping through a leaking underground pipe before being brought to the surface by July's flooding.
In its report, HSE concluded that live strain of virus entered the effluent drainage system from a pipeline between 22 and 26 July. It believes that the pathogen leaked from the buried pipework between the Merial and IAH buildings.
The virus contaminated the surrounding soil either through overflowing of a manhole and/or a leakage around the drainage pipes, said HSE. It is likely, it added, that floodwater spread the virus onto the tyres of vehicles using the site which then transferred it to local farms.??
"The inadequate levels of containment offered by the effluent drainage system represent a breach to the biosecurity arrangements at the Pirbright site," said Dr Paul Logan Pirbright lead investigator.
HSE also expressed concerns about the chemical treatment systems for sterilising liquid waste containing SAPO Category 4 pathogens. These treatments, while reducing the amount of pathogen in the liquid, may not render the liquid completely pathogen-free.
The HSE investigation found other serious deficiencies in the operation of the Surrey site, many of which failed to meet the requirements for handling dangerous biosubstances:
- Laboratory filter arrangements did not allow filters to be tested independently
- Lack of a written standard operating procedures to deal with blockages in the effluent drainage system
- Failure to properly manage contractors working around the effluent drainage system.
"Neither the existing effluent drainage system in use across the Pirbright site nor the record keeping, maintenance and monitoring regimes in place for it are considered to meet the standards required for SAPO Level 4," commented Logan.
Likewise, Keith Plumb, a chartered chemical engineer and biosecurity expert, believes the incident indicates that there were lapses in safety, maintenance and virus handling, in particular the way in which Merial was apparently allowed to transfer untreated effluent from their premises to the IAH.
"A virulent and persistent virus like Foot & Mouth Disease should be destroyed within the same building as it is being handled and not transferred anywhere else, said Plumb, who is also an independent expert for the IChemE.
Best practice in process engineering suggests running the pipe above ground, making leak detection much easier, continued Plumb. "The further layer of protection would be provided by a double pipe system that contained any leaks and this could be backed up by an automatic leak detection system."
A set-up like the one at Pirbright, where an underground pipe transfers harmful liquid from one site to another, can also lead to confusion about who is responsible for maintenance," commented Plumb.
