Environmental swine disease surveillance
Disease surveillance plays an essential role in protecting the health and welfare of Alberta’s swine herd. Alberta Pork, working with partners in government and industry, performs routine swine disease monitoring across the province through an environmental surveillance program. The goal of the program is to help protect the Alberta pork industry by identifying and mitigating swine disease risks.
Surveillance involves routine sample collection, with a focus on high-traffic areas where pigs are moved. The frequency of sampling at specific sites depends on the number of animals moved through those sites. Through this program, nearly 250 samples are collected every month in Alberta from more than a dozen assembly yards, processing facilities and truck washes.
After collection, samples are processed at Alberta Agriculture and Forestry’s molecular biology lab using a polymerase chain reaction (PCR) method, which allows for detection of the DNA or RNA of a disease pathogen. During analysis, sample status is determined as either positive (virus was detected at a certain level), inconclusive (very small amount may be present but questionable), and negative (no detection of the pathogen).
Unfortunately, PCR testing does not allow differentiation between live, viable virus and virus/viral parts that are no longer infectious. Positive results can be further evaluated based on the “strength” of the reaction in the test, whereby a “strong” positive refers to a likelihood the pathogen in a sample was being actively shed by an animal. A “weak” positive may suggest that there was just a low amount of virus being shed by the animals or that environmental contamination with non-viable virus occurred. In these cases, the result needs to be evaluated along with other information including the current situation in the herds that had animals moving through that site.
See below a summary of environmental surveillance.
|Total number of samples taken||Total number of positive samples|
See below a list of environmental disease incidents. On-farm outbreaks are not included in this list.
|Jan. 23, 2020||PED||Weak positive|
|Jan. 16, 2020||PED||Weak positive|
|Oct. 31, 2014||PED||Environmental contamination|
|Oct. 9, 2014||Delta coronavirus*||Positive|
*This incident was eventually determine to be an avian, not a swine strain of delta coronavirus.
See below sampling data for the environmental disease surveillance program.