Climate change fears for deadly virus outbreaks in livestock

March 31, 2009

Global warming could have chilling consequences for European livestock, warned Professor Peter Mertens from the Institute for Animal Health, at this week's meeting of the Society for General Microbiology in Harrogate.

Since 1998, rising temperatures have led to outbreaks of bluetongue (BT) across most of Europe, which have killed over 2 million ruminants (mainly sheep). The outbreak (the largest on record) caused by Bluetongue serotype 8 (BTV-8), which started in the Netherlands and Belgium during 2006, has since spread to most European countries, including the UK in August and September 2007. This outbreak, the first ever recorded in northern Europe, was not an isolated event. There are also fears that related viruses, such as African horse sickness virus, which can have a fatality rate of more than 95% and shares the same insect vectors as bluetongue, could also be introduced.

Bluetongue is spread by the biting midge, Culicoides imicola, which has recently colonised the northern Mediterranean coast, leading to outbreaks in affected regions. However, BT outbreaks have also been spread by other novel vector species of midge (C.pulicaris and C obsoletus groups), which are abundant across the whole of central and northern Europe. In experiments, a single bite from a fully infected midge can transmit the virus and as midges are blown across Europe "like aerial " it is almost impossible to prevent them getting to the United Kingdom.

Warmer weather increases the rate of infection and in the midge itself, and increases their activity in more northern areas. Indeed, the 2006 outbreak started in the Netherlands when temperatures were six degrees higher than previously recorded. Mild winters may also play a significant part in the problem, as the midges that are not killed by the cold (in the absence of frosts) may survive in sufficient numbers to maintain a reservoir of the disease. It is clear that BTV-8 can also be transmitted directly between cattle, providing an overwintering mechanism for the virus to survive from one midge season to the next.

"We have seen outbreaks caused by twelve strains, from nine distinct serotypes of bluetongue virus, which have arrived in Europe via at least four different routes since 1998", said Professor Mertens, "This indicates that there has been a fundamental shift in bluetongue epidemiology, linked to climate change. In 2008 the UK vaccinated over 10 million sheep and cows against BTV-8 and was the only country in Europe to successfully suppress the disease outbreak. However different BT virus types have subsequently arrived in northern Europe which represent further threats to the UK for 2009 and beyond."

"These events demonstrate that the whole region is now at risk from further incursions of BT virus, as well as other insect transmitted viruses, many of which can also affect humans. Although the vaccines against BT virus currently available for use in northern Europe are relatively crude, as they are made from inactivated virus grown in tissue culture cells, it is clear that they can work against BTV-8. However, more advanced vaccines, made from the protein-subunits of the virus, along with diagnostic tests that can distinguish vaccinated from infected animals, are urgently needed. Vaccines are also needed for other related viruses, including African horse sickness virus, and potentially both Epizootic haemorrhagic disease virus and Equine encephalosis virus."

Source: Society for General Microbiology

Explore further: Towards understanding bluetongue outbreaks

Related Stories

Towards understanding bluetongue outbreaks

August 14, 2008

A recent article published in Virology, reports the identification of a bluetongue virus strain that caused the northern European Bluetongue outbreak in 2006. Comparison of the virus strain with the sequences of other previously ...

How does bluetongue virus survive through the winter?

August 26, 2008

In 2006, Bluetongue virus – which infects livestock – reached Northern Europe for the first time. Some people thought that the outbreak would be limited to that particular year, as winter was expected to kill off the ...

The way to a virus' 'heart' is through its enzymes

July 9, 2008

The arrival of bluetongue virus (BTV) in the UK last year posed a major threat to the economy and the increasing temperatures of our changing climate mean it is here to stay. If we are to fight this disease, which has had ...

Researchers examine role of climate change in disease spread

February 5, 2009

GALVESTON, Texas — Ever since scientists first proposed that our planet might be experiencing widespread climate change, concerns have been raised about its implications for the spread of arboviruses - viruses carried by ...

Recommended for you

Venom shape untangles scorpion family tree

November 14, 2018

As a child growing up in Mexico, Carlos Santibanez-Lopez feared the scorpions that would often decorate the walls and ceilings of his home in search of a warm place with plenty of food.

Gene-edited food is coming, but will shoppers buy?

November 14, 2018

The next generation of biotech food is headed for the grocery aisles, and first up may be salad dressings or granola bars made with soybean oil genetically tweaked to be good for your heart.

Visualizing 'unfurling' microtubule growth

November 13, 2018

Living cells depend absolutely on tubulin, a protein that forms hollow tube-like polymers, called microtubules, that form scaffolding for moving materials inside the cell. Tubulin-based microtubule scaffolding allows cells ...

DNA structure impacts rate and accuracy of DNA synthesis

November 13, 2018

The speed and error rate of DNA synthesis is influenced by the three-dimensional structure of the DNA. Using "third-generation" genome-wide DNA sequencing data, a team of researchers from Penn State and the Czech Academy ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.