IAH and collaborators in the University of Edinburgh have uncovered a window of opportunity when it is possible to identify cattle infected with foot-and-mouth disease virus (FMDV) before they become infectious and/or show signs of having the disease. They have published their findings in the journal Science*. IAH experts along with colleagues at Defra (Department for Environment, Food, and Rural Affairs) are now assessing if this window of opportunity can be exploited to reduce the number of animals that are culled during an outbreak.
The research, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), has revealed for the first time that the period in which cattle are infectious before they show clinical signs of disease is much shorter than previously thought. One consequence is that diagnosis of FMDV infection is possible during the approximately 24 hours before an infected animal becomes infectious.
Importantly, if this short window of opportunity is to be exploited there is a need for further development of effective and efficient in-field diagnostic tools that can detect the virus as early as researchers have been able to do in the laboratory.
Dr Bryan Charleston who led the team at the Institute for Animal Health said “Our discovery is good news and we hope that it will enable future refinement of the methods we use to control FMDV in the UK and beyond. That said, there are a huge number of factors involved in decisions about controlling this serious and fast-spreading virus. We have proof that it is possible to detect the virus in animals before they display signs of disease and before passing the infection on to other susceptible livestock, but there are a lot of other variables to consider before it is possible to come up with a new control strategy.
“Not least, this result emphasises the need for practical tools for pre-clinical diagnosis and at present we don’t have an affordable, reliable, test to use on farms. We can identify infected cattle before they show signs of disease using tests in the laboratory; the next challenge is to do it in the field during an outbreak. This type of testing was successfully applied during the 2007 outbreak in Surrey on the basis of studies at IAH, including the early results of this research. We now need to develop the technology further with Defra in order to realise the potential benefits and possibly reduce the number of animals culled during an outbreak.”
During the 2007 outbreak of FMDV preclinical testing of animals not yet showing signs of the disease was done every second day. This was successful in identifying infected cattle that were not showing clinical signs. The very early results of this project – which was funded by BBSRC in response to the 2001 outbreak – and other research programmes informed the decision to take that approach in 2007. This proved an excellent example of how the close interaction between research and diagnostic laboratories at the IAH can accelerate the application of high quality science.
Professor Mark Woolhouse who led the University of Edinburgh team said “This new information pins down the critical times for the detection and control of foot-and-mouth disease much more accurately. We now know that there is a window where if affected cattle are detected and removed promptly, there may be no need for pre-emptive culling in the immediate area of an infected farm.
“This does make it very important that the disease is picked up quickly and farmers and others who care for livestock will continue to play a critical role. The only way we know that the disease is active is when an animal shows up with signs of the disease, which is too late. We now have an opportunity to develop new test systems which can detect infected animals earlier and reduce the spread of the disease.”
The research was funded by BBSRC as part of its Combating Viral Diseases of Livestock Initiative. The initiative
was launched by BBSRC to further our understanding of damaging livestock diseases that cause significant
economic, welfare and food security challenges. The IAH’s FMD research is within its
Livestock Viral Diseases Programme, headed by Dr Charleston.
*This research is published in a paper entitled ‘Relationship Between Clinical Symptoms and Transmission of
an Infectious Disease and the Implications for Control’ and will be available online to subscribers of
Science from 1900hrs (BST) Thursday 05 May 2011 from: