PRRS Corner: Standardizing PRRS Terminology (Part 1 of 2)

February 8, 2012 — 

The goal of the next two PRRS Corner installments is to emphasize the importance of efforts to standardize the terminology we use to describe the PRRS status of swine breeding herds. Drs. Derald Holtkamp and Dale Polson authored a publication summarizing a herd classification system developed in collaboration with a committee of PRRS experts assembled by AASV, NPB and PRRS-CAP. The AASV Board of Directors approved this classification system in March 2010. The classification system categorizes breeding herds into one of four categories (I, II (A or B), III, or IV). Categories I, III and IV are relatively straightforward and will be discussed in Part 1. Category II divides herds into one of two subcategories and will be explored in Part 2 (next week). This paper was published in the January/February 2011 issue of JSHAP.

Classification Categories:

• Positive Unstable (Category I): Herds undergoing active outbreaks with positive shedding and exposure statuses. Also the default category for herds of unknown status.
• Positive Stable (Category IIA or IIB): Will be discussed in next week’s article due to its complexity.
• Provisional Negative (Category III): Negative shedding status. Requires sustained introduction of negative breeding herd replacements that remain seronegative for a minimum of 60 days with close contact with previously positive animals. On-site grow/finish pigs must also test negative for exposure.
• Negative (Category IV): Negative shedding and exposure status of the breeding herd. Confirmation of negative status of any resident grow/finish pigs. Negative status may be achieved through diagnostics in combination with production records for herds established negative through herd rollover or through a negative herd test on animals resident in the herd for a minimum of 1 year.

Next week we will explore the Category II designation in more detail. The complete publication is available for review online.