SHIC Funds Research on Unusual Strep Outbreak in Pigs

11:24AM Nov 11, 2019
Nursery pigs
( National Pork Board and the Pork Checkoff )

A strep bacteria, commonly found in horses that can lead to strangles, was isolated from two recent cases of high sow and feeder pig mortality in U.S. assembly yards, reports the Swine Health Information Center (SHIC).

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a commensal organism in horses and is not unusual, says Paul Sundberg, DVM, SHIC executive director. 

“But what is unusual is that this strep got into pigs and caused the problems it caused,” Sundberg says. “This strain has also gotten into dogs. There have been kennels that have been depopulated and cleaned because dogs have gotten this particular strep as well. This is a horse strep that has gotten into other species and caused disease.”

The symptom presenting in pigs was sudden death, Sundberg says. And the deaths occurred in pigs of all ages and in high numbers. This strep bacteria has been traced back to the ATCC strain that originally caused high mortality during an outbreak in China in the mid-1970s, he adds, resulting in the loss of more than 300,000 pigs. 

“Within a short period of time this year, this same strep strain has shown up in Manitoba (Canada), Wisconsin, Ohio, Tennessee and perhaps in North Carolina. This strain has worked its way through these pig populations and caused fairly high mortality,” Sundberg says.

In addition to increasing pig farm biosecurity efforts, particularly related to transport and collection points, Sundberg says producers should be on the lookout for high mortality losses in all ages of pigs (weaned pigs to sows).

“If you have a mortality event on the farm, get a veterinarian to take a look. Whether high mortality or one animal, don’t assume you know what you have, get professional help,” he advises.

Further work needed
SHIC is funding further research to better understand the relevance of S. zooepidemicus in North American swine, including characterization of the bacteria at the Iowa State University Veterinary Diagnostic Lab (ISU VDL), to find out why this strain caused the problem it did in pigs. 

“It is urgent. We want to know its pathogenicity, we want to know the areas of the bacteria that caused problems in pigs and we want to make sure we are prepared if it continues to cause a problem so we can react to it and stop it as quickly as possible,” Sundberg says. 

They are sequencing the genome and doing inoculation studies in pigs so they can follow the infection in a controlled manner and doing studies on pigs with the infection so they know how to prevent it should it continue, he says. 


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