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From the Institute for Animal Health


Bluetongue virus might survive the winter within foetuses

Scientists in the Institute for Animal Health believe that it is a distinct possibility that bluetongue virus survives the winter by passing from pregnant infected ruminants to their offspring whilst in the womb. After birth, the young animals provide biting midges (the “vector”) with a fresh source of virus when they take a blood meal.

Knowing how the virus over-winters is a vital before the 2008 vector season gets underway, as it might be possible to introduce preventative measures before transmission re-commences.

This is especially important in the UK where so far the virus has been limited to a restricted area within England, largely in the east, and may still be able to be eradicated.

“In essence we have a once-only opportunity to eliminate the virus from the UK before it devastates our ruminant industry as it has already done on the near continent in 2007.” said Professor Philip Mellor, Head of bluetongue research within the Institute for Animal Health.

The Biotechnology and Biological Sciences Research Council (BBSRC) has just provided financial resources to Professor Mellor’s team to investigate if bluetongue virus is surviving in this way, and potentially fuelling a 2008 outbreak.

This investigation has been prompted by recent observations in Holland and the UK that indicate that ruminant offspring that are weak, still-born, and/or PCR* positive are now being born to dams that were infected with bluetongue virus last year.


For more information you might choose to visit the website of the Institute for Animal Health,, starting especially with this link: Copies of the presentations made by IAH experts at January’s National Farmers’ Union – IAH Bluetongue Conference can be found by starting at the Farmers page, and then following the ‘useful links’ on the left of the screen.

If you would like to speak to our bluetongue experts, contact Dr Dave Cavanagh at the Institute for Animal Health’s press office: mobile 07789 941568 (message can be recorded); office 01635 577241 (message can be recorded);

Notes for Editors

*PCR, the polymerase chain reaction. This technique detects the genetic material of the bluetongue virus, and is briefly described at

Transplacental infection of the foetus of dams infected during pregnancy to produce offspring with blood-borne bluetongue virus during the next vector season.

Until recently most bluetongue scientific authorities agreed that transplacental infection of the ruminant foetus by bluetongue virus from a dam infected during pregnancy only occurred when laboratory-adapted strains of virus were used. In experiments with these strains of virus, resorption of the foetus, abortion, birth of weak or deformed offspring ensued. Some of the offspring had bluetongue virus in their bloodstream (“viraemic”). Work at IAH-Pirbright in the 1970s showed that infectious virus was present in the offspring up to 60 days after birth. As the dams had been infected at around 60-70 days of gestation, this means that there was a period of approximately 145 days between infection of the dam and end of viraemia in the lamb. Such a time would easily cover the period from the end of one transmission season (December; when the temperatures are too cold for midge activity and too cold for the virus to grow in midges) to the start of the next (April; when temperatures rise sufficiently) in the UK and elsewhere in northern Europe. The body temperature of the midges is the same as that of their surroundings.

The Institute for Animal Health is the largest research institute in the United Kingdom dedicated to the study of infectious diseases in farm animals. It has two campuses: Pirbright Laboratory (Pirbright, near Guildford, Surrey) and Compton Laboratory (Compton, near Newbury, Berkshire) IAH is one of seven research institutes sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC;