Swine disease surveillance is of great importance to the swine industry in order to raise and provide healthy animal populations. In order to insure timely disease intervention for optimal animal health, surveillance methods and sampling options need to be readily available. Many of our diagnostic sample collections are based on individual animal samples, i.e. serum, blood swabs, nasal swabs, etc. These individual sample diagnostics are then commonly used to infer information on the population level. In order to understand population status from a collection of individual samples, diagnostic and sampling methods require evaluation.

As reviewed in Chapter 1, the pooling of individual samples is commonly place in various fields of veterinary medicine. In order to properly utilize this diagnostic strategy all the factors that affect pooling results need to be understood. Pooled diagnostics are influenced by the type of analyte, stage of infection, sample dilution, matrix components, the prevalence of disease, and laboratory differences. In order to attain accurate diagnostics and to properly pooling interpret results, these factors must be accounted for.

In continuation of the study of disease surveillance methods, the objective of the first research paper (Chapter 2) was to evaluate different sample collection techniques for the early detection Porcine Respiratory and Reproductive Syndrome Virus (PRRSV) in a boar stud population based in individual sampling techniques. Diagnostic specimens analyzed in this study included serum, oral fluid, blood swabs, frothy saliva, and semen. Semen samples were centrifuged and the seminal supernatant and cell fractions were tested separately. All samples were randomly ordered and tested for PRRSV by real-time quantitative reverse-transcriptase polymerase chain reaction (rRT-PCR) and PRRSV antibody ELISA. No statistically significant differences were found between serum, blood swabs, and oral fluids in the onset of detection but numerical differences did exist.

The objective of the second study (Chapter 3) was to evaluate if the oral fluid training and collection methods used for the boars in Chapter 2 could be applied to individually housed commercial sows. This study also analyzed the diagnostic reproducibility of PCR and ELISA results from the same animals. To achieve this, oral fluid sample collection was attempted on 513 individually housed; mixed parity sows naive to oral fluid collection. Oral fluid collection was attempted for each animal on two successive days under the same collection conditions. Successful paired oral fluid samples were randomly selected, randomized for submission, and tested by PRRSV PCR and oral fluid ELISA for anti-PRRSV antibodies. Younger sows and the re-sampling of animals were positively associated with collection success and diagnostic results collected on two successive days were correlated.