It is difficult to see the circulation of PRRS on a farm due to their being a variety of symptoms.

It can the fertility of sows and is also seen in the nursery and fattening stages, making it hard to diagnose.

One thing we know for sure is that it is circulating on all farms, said veterinarian Luk Willems.

To try and prevent the spread, Mr Willems has been implementing a dual-technology prime-boost vaccination scheme in sows?

The idea is to have stronger immunity and antibiodies for piglets at farrowing through delivery of the vaccine in the colostrum of sows and then also a live vaccine to reducing the circulation of the virus in sow units.

So, to do this, a killed vaccine was given three weeks before farrowing and then a live vaccine given after farrowing.

The results were that less problems and an improvement in growth were seen in the nursery. Less respiratory problems and a slight improvement in growth was seen in the fattening units and better health of sows with bigger litters was also reported.