6 May 2011

4 minute read

Europe

Researchers at the Institute for Animal Health (IAH) along with colleagues at Defra (the UK 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 researchers, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), have shown 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.

The research, carried out at IAH, which receives strategic funding from BBSRC, and the University of Edinburgh, demonstrates that diagnosis of FMDV infection is possible during the approximately 24 hours before the 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 using laboratory techniques.

In addition, similar studies could be performed for other acute viral diseases such as influenza. This would help refine our understanding of how diseases spread and choose the most appropriate measures to control an outbreak.

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 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."

Professor Douglas Kell, Chief Executive, BBSRC said: "Foot–and–mouth disease has had a devastating impact in the UK in the past. This excellent research brings together top expertise in virology and epidemiology to get to the bottom of how this virus behaves. It is this thorough understanding of the causes of animal disease that will underpin future food security in the UK and ensure that we can maintain a healthy farming industry"

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.