Sometimes (say, when you’re waiting for the fields to dry out so you can go about the business of spring planting) there is value in spending a little time recalling past successes.
Such is the case with porcine circovirus type 2 (PCV2) in growing pigs in North America since commercial vaccines became available in 2007. Figure 1 shows the proportion of cases in which the University of Minnesota Veterinary Diagnostic Laboratory has detected PCV2 from tissue samples by polymerase chain reaction (PCR) testing. The overall trend for virus detection followed closely our observation of the decline in clinical case submissions of circovirus disease that coincided with widespread vaccine application.
As the graph shows, we still find virus in a low proportion of tissue cases, often at low concentrations and in the absence of lesions. We also find occasional clinical cases, with the classic clinical presentation and gross and histologic lesions. Most often, these cases are from herds that are located in remote regions that up to now had not needed to vaccinate.
Occasionally, we see cases in which pigs were vaccinated in the face of massive PRRS (porcine reproductive and respiratory syndrome) virus circulation.
The impacts of the vaccination on the clinical effects of this virus, and the subsequent impact on hog markets, have been well documented.
Individuals who forsaw the clinical scenario and tried to prepare the rest of us for it deserve accolades for their diligence.
Click to view graph.
Jerry Torrison, DVM
University of Minnesota Veterinary Diagnostic Laboratory