Resurgence of ‘old’ bacterial diseases in pigs: Why?

Three bacterial diseases considered under control recently flared up creating new challenges in hog operations. The older diseases include Haemophilus parasuis (parasuis), Streptococcus suis (strep) and erysipelas.

“They are pretty old bugs that generally we thought we had under good control,” reported Aaron Lower, DVM, Carthage Veterinary Service. “The bugs, they continue to outsmart us and…continue to change and adapt in order to stay prevalent.”

Parasuis- and strep-control options

Parasuis can be found in all pigs. “We don’t quite understand what makes it virulent in some pigs versus not virulent in other pigs,” Lower told Pig Health Today.

They can control it with single-source flow and eradicating other viral diseases like influenza and strep. But in some cases, they still see clinical signs of the disease in pigs near weaning to post-weaning.

Strep has been a little easier to control. “If we could eradicate, manage wean age and the other viral diseases, we didn’t have much of an issue with it,” Lower said.

“About 4 years ago, we didn’t use any autogenous vaccines for strep or parasuis,” he continued. “Unfortunately, in a couple of flows now, we’ve got those vaccines in pretty consistently…We see good response to the vaccine. It generally makes [pigs] 80% to 90% better.”

Erysipelas comeback

In the past 10 years, Lower said they nearly eliminated grow-finish erysipelas vaccinations. But in the last two winters, the disease has made a comeback.

“We’ll see it at various different ages, late nursery all the way through finishing, and concurrently…also some at the sow farm,” he explained. This leads him to believe it is also an issue in the sow farm.

“The intervention has been to go back in the sow farm and do some mass vaccinations or increase vaccination frequency.”

Fewer antibiotics, more vaccines

“Over the last 2 years, there’s been a dramatic decrease in antibiotic usage from the industry, which has been good,” Lower said. “But these [old diseases] may be some of those negative repercussions.  We’ve just got to figure out how to manage that, whether it’s immunity at the sow farm, putting the vaccine back into grow-finish flows or strategic placement of antibiotics.

“The good news is we have a decent amount of vaccine tools…as we pull back on antibiotic usage,” he  said. “We’d always like more tools because some of those pathogens…mutate and change as they try to get ahead of us.”