SHIC Study Examines Changing Surveillance Practices for Better Results

In a recently completed study funded by the Swine Health Information Center (SHIC), contemporary emerging and foreign animal disease (FAD) surveillance practices were studied. One of the study's authors, Dr. Jeff Zimmerman of Iowa State University, points out the dramatic change the domestic pork production industry has experienced over just a few years with much larger herds and populations in regional areas. "Bigger herds have much more traffic including trucks, people, feed, and movement of pigs between sites," he observed. "That increases the likelihood and speed of disease transmission."

In the executive summary for the study, "Development of regional surveillance systems for emerging and foreign animal diseases of swine," it states, "Effective surveillance should efficiently collect data for production and/or business planning, document freedom from specific pathogens, and guide a rapid, effective response to emerging and/or FADs. Current on-farm or regional surveillance programs routinely fail to meet these targets. In part, this is because the industry has changed over time and no longer conforms to the assumptions under which our surveillance systems were originally designed. As a result, surveillance either is not done or is done ineffectively."

Ineffectiveness of current surveillance practices was confirmed with the outbreak of porcine epidemic diarrhea virus (PEDV) when the disease progressed at a pace far faster than confirmed diagnosis. Syndromic surveillance delayed detection of foot-and-mouth disease in Europe and classical swine fever (CSF) in Europe and South America. In the past, random sampling was the standard, however, Dr. Zimmerman points out this assumes the disease is also random which the industry recognizes is not the case.

In the course of the study, the researchers compared five methods for surveillance. Their work determined spatially balanced surveillance evaluating diagnostic submissions could provide the efficient system being sought. "Veterinary diagnostic labs have massive samples coming in on a routine basis," Dr. Zimmerman stated. These samples reflect the reality of current production practices with continuous flows of pigs.

"Spatially balanced surveillance detected pathogens earlier at lower prevalence," Dr. Zimmerman said. "This process is more likely to detect a pathogen than simple random sampling." Other advantages are having the samples on hand at diagnostic labs and providing for continuous surveillance efforts. "If there are concerns over African swine fever or other pathogens, this system could be implemented at a pretty low cost," he concluded.

Work so far has focused on submissions to the Iowa State University Veterinary Diagnostic lab. Dr. Zimmerman sees next steps including expanding to include other labs as well as working with USDA partners.

Funded by America's pork producers to protect and enhance the health of the US swine herd, the Swine Health Information Center focuses its efforts on prevention, preparedness, and response. As a conduit of information and research, SHIC encourages sharing of its publications and research for the benefit of swine health. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Paul Sundberg at psundberg@swinehealth.org.