Seventy percent of the cows on dairy farms have come into contact with the Schmallenberg virus. But no more than one or two deformed calves are born on these farms.
Last month, the CVI developed a test to check for anti-bodies against the Schmallenberg virus in animals. Van der Poel thinks that it is remarkable that although so many cows have come into contact with the virus, only a few calves on each farm have been infected. 'There are more infections among cows than among newly born calves. It seems that the virus cannot enter the foetus easily, or it does not always cause sickness.' Things are different among sheep, says Van der Poel. In affected sheep farms, as many as one half of the lambs are born with deformities.
The CVI now wants to also test midges for anti-bodies against the Schmallenberg virus, to find out if this insect is responsible for spreading the virus. In the meantime, Belgium and Danish researchers have shown that the virus is found in midges. The CVI is waiting for funding to enable it to carry out this work also in the Netherlands.