Aggregateddata from surveys in Scotland and Northern Ireland show that more than a thirdof herds surveyed are positive for swine influenza, according to Merial Animal Health.Between the surveys just over 280 farms were assessed and serology demonstratedthat 34% were positive.
Thiscompares with research on pig farms in England carried out by the RoyalVeterinary College (RVC) and the COSI Consortium in 2010 which showedthat 59 per cent of herds were positive for one of the swine influenza strains.
The Scottish data is from figures collectedby Quality Meat Scotland based on blood samples taken in 2012 and 2013. TheNorthern Irish data was gathered at the two main slaughter houses in theProvince in 2011.
CallumBlair, Merial Animal Health said: We would suspect that the results of bloodtests at slaughter are an under-estimate of the actual prevalence of swineinfluenza as antibodies from natural infection wane over time. Pigs that mayhave been affected, therefore, could still test negative at slaughter. Soit may be that the prevalence is even higher than a third of herds.
Thedisease can be sub-clinical and the productivity of the herd can fall beforethe disease is detected. By this point, treatment can be costly and pigshealth severely compromised.
Hecontinued: In the case of the Northern Irish study there also seemed to be alink between the prevalence of swine influenza and pericarditis (infectionaround the heart) and pleuritis (infection around the lungs).
Swineinfluenza can also significantly increase herd replacement rates. It increasesthe likelihood of both abortion and still births. The disease can affectconception rates and decrease lactation, both of which add to a decrease inherd output.
GRIPOVAC3 is the only approved swine influenza vaccine on the UK market and is approvedfor all three of the main subtypes of the disease, adds Merial.