Better Pork - October 2006

Feature

Two vaccines show promise in controlling costly circovirus losses

by KATE PROCTER

As test results come in, vets are moving from cautious optimism to enthusiasm about the vaccines efficacy

There may be light at the end of the tunnel for Ontario producers who have been battling the ravages of circovirus. Results from two new vaccines are starting to come in and the news so far is nothing but good.

Two vaccines are available on emergency import permits for Canadian producers -- Merial’s Circovac, which is administered to sows, and Intervet’s PCV2 vaccine. This vaccine is labelled for pigs that are at least three weeks of age and requires a booster shot. Circovac has been available since February and is administered to the sow prior to farrowing. The sow must be given a booster shot after the first dose and then subsequent litters require just one shot. The vaccine costs about $6 per dose.

More than one million sows have been treated with Circovac in Europe, showing “positive and promising results” says swine veterinarian Dr. Doug MacDougald. As the first pigs born in Ontario from treated sows approach the early to mid-finisher stage, he remains cautiously optimistic, but these pigs are coming into their most challenging stage of growth.

Dr. Nancy Charlton is with the Linwood Veterinary Service. One of her clients vaccinated using Circovac in April and farrowed those sows in May. Prior to vaccinating, this producer was experiencing between seven and 14 percent nursery losses. After using Circovac, his nursery losses are now down to one to two per cent.

Intervet’s PCV2 vaccine may show even more promise. Thousands of piglets were vaccinated in Canada in a safety trial prior to its approval for emergency release by the Canadian Food Inspection Agency (CFIA). As results from these piglets come in, MacDougald says, I have moved past cautious optimism. There are groups in finishing barns that have been entirely vaccinated and are almost ready to go to market that have seen complete control of the clinical signs associated with circovirus disease. These groups have experienced significant reduction in mortality, which has dropped from 7.6 per cent in the previous unvaccinated group to 1.6 per cent in the vaccinated group.

In another finisher, half the pigs were vaccinated and half weren’t. At 11 weeks, the current mortality rate in the vaccinated group is 1.9 per cent compared to 4.3 per cent in the unvaccinated group. The previous unvaccinated group in this facility had a mortality of five per cent.

Dr. Marie-Claude Germain supervises about 300,000 pigs, including sows, nursery and finishing pigs in Quebec. More than 90 per cent of her clients have seen problems associated with circovirus, she says, with mortality rates ranging from four to 30 per cent.

Germain used Intervet’s vaccine, which costs between $1.60 and $2 per piglet.

Two groups of piglets were vaccinated. Group A included 5,000 piglets, which were Porcine Reproductive and Respiratory Syndrome (PRRS)- and Mycoplasma-negative and had an eight per cent mortality rate. Group B included 3,000 piglets, which were PRRS- and Mycoplasma-positive and had between 10 and 15 per cent mortality rate.

“On those piglets, it was wonderful,” she says. Group B experienced no problems, showed no clinical signs of disease and the pigs grew very fast.

Another group that were PRRS- and Mycoplasma-positive had a 15 per cent morbidity and between eight and 15 per cent mortality. All 1,200 piglets were vaccinated and, after seven weeks in the finishing barn, only eight were dead.

“It’s amazing,” she says. There were no clinical signs of disease associated with circovirus, which had been a problem in this herd for over a year and a half. “The vaccine had very, very good efficacy.” BP