Eradicating Blue Ear/PRRSV now ‘possible’

Eradication of Blue Ear/PRRSV is possible, Danish expert Anders Elvstrom told Irish pig producers recently.

In his region of Denmark, positives have been reduced from 90% to 30%, he told a Teagasc meeting in Portlaoise.

“Our advantage is that we have a multi-site production system. Ireland would be at a disadvantage on this basis in that it would be more difficult to eradicate the disease from integrated herds.”

Mr Elvstrom said multi-site production is key to successful eradication, it is most important that finishers are moved to a separate site away from the sow herd, this stops the virus spreading in the herd.

If all gilts are vaccinated with live vaccine, they will shed the virus for four to six weeks. This should always take place in quarantine, on another site for at least eight weeks, but 12 weeks ideally. Piglets born subsequently are negative for the virus and the virus can be eradicated by a strict all-in/all-out practice.

Since Blue Ear/PRRSV flared up in the spring, strategic vaccination of at-risk farms has been recommended.

Mr Elvstrom, from Svinepraksis in Denmark, answered the questions of farmers and pig sector personnel.

*In the case of an acute outbreak, what procedure should be followed?

>>Vaccinate all pigs, sows, gilts and piglets/weaners. This will help speed up the process of elimination.

*Can you summarise your protocol for vaccination?

>>Negative herds: do nothing. Do not use the live vaccine, it may cause clinical signs, and it is too risky to have the real virus circulating. Blood test these farms at least once a year for the PRRS virus and/or on suspicion of any symptoms occurring on the farm.

Positive herds with clinical symptoms: vaccinate gilts and sows and also piglets if there are symptoms in the finisher stage. Positive herd, no symptoms: vaccinate gilts and sows now and continue on an ongoing basis by vaccinating gilts as they come into the herd. You may also need to use antibiotics for treatment of disease on this farm. Don’t wait for the symptoms, vaccinate.

*Is there any risk of spreading disease through slurry?

>>We don’t consider slurry a factor in carrying PRRS in Denmark. We do not have any limitations from where slurry on positive farms can be spread, but in Denmark we mostly spread with a bandspreader or direct injection into the ground.

*How does the PRRS virus spread and are there times of the year when it is more susceptible to spreading?

>>Mainly it spreads via pigs through incoming stock or in the air. It can travel up to 4 or 5 kilometres in the air. Spread is more common in winter time as the virus is more suited to a cold climate.

*If the sow is vaccinated, will it pass the virus onto piglets?

>>The virus will be carried into the growing herd through the piglets. It may or may not cause problems, symptoms may or may not be seen. In terms of vaccination, it’s a financial issue really, and to be safe you may need to vaccinate all animals, gilts, sows and piglets.

*In addition to vaccination, what biosecurity measures should be used?

>>You need to look at your farm in terms of overall biosecurity. Quarantine is very important. The biggest risk in Denmark is incoming stock onto a farm. Quarantine ideally for 12 weeks but minimum eight weeks for any incoming stock. Gilts and boars should be blood tested twice in quarantine before introduction to the main herd.

*Are disinfectants effective against PRRS virus?

>>Yes, the virus is easily inactivated by most common disinfectants.

*My herd is positive for PRRS but I have no clinical signs. I have vaccinated my sows. What strategy should I pursue? >>Continue vaccinating the gilts at least. You may consider doing all piglets if other diseases are a problem. As the unit is an integrated unit, the containment process is the best option, eradication would be very difficult.

* How soon will effects kick in after blanket vaccination?

>>For the last two thirds of pregnancy, for sows in the last two thirds of pregnancy when vaccination took place, you will have poor pigs, but after that things should be ok, about four months.

* What are your recommendations for symptoms occurring in finishers?

>>Vaccinate piglets using half the normal dose. They can be vaccinated around weaning at 7kg. Financial judgement is required.

* If grower/finisher symptoms merit vaccination, when should you vaccinate?

>>Vaccinate them at weaning. You can vaccinate for PCV and other diseases at the same time.

* How long should you vaccinate piglets if there are clinical problems on-farm?

>>Continue vaccination until first piglets vaccinated are gone through to slaughter and see how symptoms look at that stage. Then you can re-evaluate your programme.

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