[Hablemos de rumiantes n°1] Current scenario of vector-borne diseases in ruminants

If you are involved in the production of cattle or small ruminants, it is very likely that, in the last two years, you have been confronted with the Bluetongue virus (BT/BTV) or the Epizootic Hemorrhagic Disease virus (EHD/EHDV); from a clinical point of view, or because of the impact on animal movements. Analysing the situation in perspective, it seems clear that today we find ourselves in a new epidemiological scenario with respect to viral vector diseases that affect ruminants, specifically orbiviruses.

What factors motivate the scenario in which we are moving?

There are several factors that motivate this current scenario and that will probably condition even more the recirculation of these viruses in Europe during the next years:

• Climate change is logically behind the expansion of the culicoides, since there are milder temperatures in winter and longer periods of temperatures within the vector’s activity range.
• The appearance of new serotypes such as BTV3, which is much more virulent and, therefore, has a greater economic impact.
• The high infection pressure of both EHDV and multiple BTV serotypes on the ruminant population leads to animals infected with more than one serotype, increasing the risk of genetic recombination.
• The wild ruminant population is also affected, providing a reservoir for both viruses.

Thus, in practice, vaccines are the only tool for the battle against vector-borne and multi-host diseases, such as EHD or BT. Vaccines decrease the infective pressure on the sheep and cattle population, thereby helping to avoid new recombinations that may generate strains that are more virulent and/or more unpredictable in their behaviour.