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TREATING STREP ZOO: USDA said that Streptococcus zooepidemicus bacteria are largely susceptible to antibiotics such as penicillins, amoxicillin, ampicillin and cephalosporins.

Pennsylvania swine industry on alert after Strep zoo discovery

Streptococcus zooepidemicus was identified in a sick cull sow at an approved livestock market in the state.

Streptococcus zooepidemicus, also known as Strep zoo, has been found in Pennsylvania after authorities identified the bacteria in a cull sow that died at an approved livestock market.

According to an alert from PennAg Industries, the Pennsylvania Department of Agriculture, in conjunction with USDA Veterinary Services, recently investigated the loss of a cull sow with heavy growth of Strep zoo. The alert states that the sow was in poor body condition and debilitated, and that it was consigned by a small livestock dealer-hauler along with four other sows in a similar state. 

The sow had apparently passed through a livestock dealer-hauler that had a recent spike in mortality in their holding facility. The dealer-hauler marketed surviving sows to a slaughter-only livestock auction.

The remaining sows were traced forward and shown to have gone to slaughter, according to the alert. In a letter to Pennsylvania Farm Show exhibitors, the ag department's Bureau of Animal Health and Diagnostic Services said that meat from the animals does not present a food safety risk if handled and prepared properly. The farm show begins this weekend and runs through next week in Harrisburg.

The holding facility where the sick sows came from is currently under quarantine for Strep zoo and diagnostic samples are pending.

Shannon Powers, spokeswoman for the Pennsylvania Department of Agriculture, said in an email that USDA was initially notified after the sow died. Federal authorities later notified the state ag department after beginning an investigation.

Testing was conducted at the Pennsylvania Veterinary Lab, and it was later revealed that the sows came from a farm in Snyder County, which is currently under quarantine.

The PennAg Industries alert said that the farm was gradually selling down its animals because the facility was run down and in need of repairs. The farm has 90 pigs. Three debilitated sows on the farm have been euthanized and diagnostic tests are pending. The rest will be moved to a slaughter facility with no possibility of diversion.

Powers said the department has no evidence that the disease is circulating in other commercial swine or in the show pig sector in Pennsylvania currently.

Dangerous disease

Strep zoo is zoonotic, meaning that it can transferred to and cause disease in humans, though it's rare.

It is not unusual to find Strep zoo in cat or dog shelters, and even in horses. But the fact that it has spread to pigs is concerning since this strain appears to be especially deadly.

In its November Emerging Risk Notice, USDA said that a high mortality event occurred in late September in a cull sow slaughter plant in Tennessee. The Food Safety and Inspection Service reported that more than 40% of 2,222 sows in the plant later tested positive for Streptococcus equi subspecies zooepidemicus (Strep zoo).

USDA reported that similar events may have occurred in other locations, including in a continuous-flow swine aggregating and buying station in Ohio that is epidemiologically linked to the event in Tennessee.

USDA said that high mortality rates in cull swine at holding facilities are unusual and that an investigation is ongoing to determine if Strep zoo is the single cause of the Tennessee deaths or if multiple factors are to blame.

Canadian authorities reported detections of Strep zoo in May as a result of swine die-offs in multiple locations.

The disease has been detected in an aggregating yard in Ohio and in slaughtering plants in Wisconsin, North Carolina and Florida. 

According to Swine Health Information Center, the bacteria found in the aggregating yards had been traced back to an ATTC strain that caused at least 300,000 pig deaths during an outbreak in China in the 1970s.

An Oct. 8 alert from the Iowa State University Veterinary Diagnostic Lab states that the lab had received only six reported isolations of the disease in the past 10 years. The rapid spread and progression of the disease in the aggregating yards and slaughtering plants suggests that much of the nation's pig herd had not previously been exposed to this strain of the disease, the report stated.

Humans and other animals can get Strep zoo by coming into contact with infected respiratory droplets and uterine exudates. Humans can also get the bacteria by drinking unpasteurized milk from sick animals with mastitis due to infection from Strep zoo, though disease, according to the alert, is rare.

On Dec. 23, the Pennsylvania Department of Agriculture designated Strep zoo as a dangerous transmissible disease in swine, giving the department authority to monitor the domestic animal population to determine the prevalence, incidence and location of transmissible disease of animals. 

Signs of disease

Clinical signs of the disease include sudden-onset lethargy, weakness, high fever and swift spread among pigs of highly varied sources, and rapidly escalating mortality approaching 30% to 50% among affected populations. 

The alert states that any Pennsylvania producer who suspects the disease in their herd should call 717-772-2852 and press option 1 to reach the veterinarian on call.  

Steps to prevent disease

PennAg Industries said that the basis of a biosecurity plan starts with establishing a distinct line of separation, which requires minimum biosecurity such as clean coveralls, clean boots, boot wash and a shower on the farm.  

Here are some steps to minimize risk from moving animals on and off the farm:

  • Pay close attention to how vehicles enter the farm, and load and unload livestock. The goal should be to never have the driver enter the facility; They should either remain in the truck or go no farther than their trailer. 
  • Require that only clean conveyances enter the farm to avoid the conveyance being a fomite to bring disease onto the farm. 
  • Farm staff should load cull animals up to but not entering the livestock trailer, and then clean and disinfect the loading chute. 
  • Exposure to direct sunlight has been shown to be beneficial as cultured Streptococcus equi has shown to survive less than 24 hours on wood, rubber and metal surfaces when in direct sunlight.

Possible treatments

USDA said that Strep zoo bacteria are largely susceptible to antibiotics such as penicillins, amoxicillin, ampicillin and cephalosporins.

Common cleaning and disinfecting procedures can inactivate the bacterium, though appropriate mechanical cleaning with disinfection should be incorporated, according to USDA.

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