Dr Susan Detmer, an associate professor in the Department of Veterinary Pathology with the Western College of Veterinary Medicine, says that both humans and pigs encounter two peaks in the flu season with the second peak striking in March and April. This year, however, the second peak has been less apparent in swine herds which Dr Detmer believes is due to the warm spring temperatures.
"The first peak usually hits by late November into December and the second peak is usually March-April," says Dr Detmer, in an interview with Farmscape.
"They did see more of that trend in humans this year. We did not see as much of a second peak in pigs this year and that has a lot to do with the high virulence and rapid spread of the pandemic virus in the pigs.
"When you get a new virus introduced into a population of pigs, that virus tends to take over and push everything aside but we didn't see as much of the natural double peak that we normally would see. We're still waiting for the end of April.
"A few years ago we had a late April-May peak so it could still happen but fortunately the weather has improved and ventilation has improved on pigs farms. When they have more ventilation in the barns they have fresher air going through and it helps relieve those flu symptoms and respiratory diseases."
Meanwhile, Dr Paul Sundberg, the Executive Director of the Swine Health Information Center (SHIC) reports that while the movement of PRRS has been relatively limited in the US this spring, there have been increased reports of porcine epidemic diarrhoea (PED) and Mycoplasma hyopneumoniae.
"PRRS has been relatively quiet this winter and into this spring as far as continued infections and spread go and so that's a welcome development. PED, however, has increased through March and that detection is at a higher level than what we would expect through an analysis of history," he explains.
"There may be a number of things going on there, including the weather, pig movement, animal movement, people moving the virus around. We don't have a lot of reports of why but certainly we are monitoring what and we're looking for that.
"Also what we've started to do is report the detection of Mycoplasma hyopneumoniae. That is an infection that has high interest right now for producers and for veterinarians for control and so we're adding Mycoplasma to the list of diseases that we're reporting about.
"There has been through March increased detection of Mycoplasma and there are higher than expected incidents based on historical information."
Dr Sundberg says the full reports as well as a link to the new on line portal are available on the SwineHealth.