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Headlines Published on 17 April 2006

Title UK scientists recruit rural communities to help combat bluetongue disease.

UK scientists studying the potentially deadly livestock disease bluetongue are calling on farmers in the region to help them better understand how it spreads. Using satellites and environmental data to support the work, the final results could help with new animal management approaches for preventing fresh outbreaks in the UK and possibly informing those European countries currently affected by the biting blight.

UK scientists recruit rural communities to help combat bluetongue disease. © PhotoDisc
UK scientists recruit rural communities to help combat bluetongue disease.
© PhotoDisc
No cases of bluetongue – a viral disease affecting mostly sheep, but also other ruminants – have been recorded in the UK in years. But that is no deterrent to British scientists wanting to learn all there is to know about this arbovirus transmitted by several species of Culicoides (biting midges or gnats).

Their findings will go towards helping to prevent fresh outbreaks at home but could also be of use in southern and eastern Europe where the disease is spreading quickly. Scientists worry that climate change is extending the disease’s footprint in Europe to more northerly climes and that it can be carried by a bigger range of biting flies – also known to be prevalent in the UK.

“Bluetongue can cause spectacular disease outbreaks and is placed in the Office International des Epizooties (OIE) List A disease category. Affected sheep may die after acute or chronic disease, or may recover with weight loss and/or wool breaks,” according to the UN’s Food and Agriculture Organisation (FAO).

On this case are researchers funded by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC) and Department for Environment Food and Rural Affairs (DEFRA). To get a full picture of midge activity in the UK, scientists are recruiting farm help. Livestock holders UK-wide are being asked to let them set up nightlight traps around their properties. The captured midges will be analysed to identify their species and determine if they are able to spread bluetongue.

“We want to better understand both the distribution of biting midges and their seasonal abundance,” explained Simon Carpenter from the UK Institute for Animal Health (IAH). The team will combine data collected using the nightlights with information from weather satellites and climate change models to predict which areas are most at threat from midges and at what time of year.

Satellites to track the spread
Although mostly affecting sheep, bluetongue can reproduce in all species of ruminant. This means that animals less affected by the disease, such as cattle, can become covert carriers of the virus, infecting more livestock. Severe cases in sheep, goats and deer can result in respiratory problems, swelling, fever and death. The IAH research team were the first to highlight its recent spread into southern Europe, according to a press statement.

”Temperature and rainfall are key variables in the ability of the carrier midges to breed and spread the virus,” the statement continues. We learn that, below 8-10 degrees Celsius, adult midge activity is reduced, increasing with warmer summer evening temperatures (i.e. 18-29 degrees).

Studies even show that the virus can lay dormant for up to a month in midges when the mercury drops to below 10 degrees, only to reactivate when temperatures rise. If winters become shorter with global warming, the scientists suggest, the midges (and hence the virus) may not be killed off. Midges require semi-aquatic breeding sites, so rainfall is important in understanding disease transmission, as well.

The team want to analyse the data gathered from farms to advise them, ultimately, on effective ways to prevent the disease spreading. Pinpointing high-risk seasons and weather hotspots when midges are most likely to spread bluetongue is key to the research. It involves studying satellite images to predict which farms are most at risk and when. “We are also analysing how insecticide usage or changing the management of livestock could help to prevent the spread of the virus by preventing animals being bitten by midges in the field,” noted the team.

Source:  BBSRC, FAO, IHA

Research DG contacts

More information:

  • Bluetongue (on FAO)
  • Food Quality and Safety programme (EU Sixth Framework Programme for research)
  • Animal Health and Welfare (Health and Consumer Protection DG)
  • Sheep (on Wikipedia)

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