title: Association of the presence of influenza A virus and porcine reproductive and respiratory syndrome virus in sow farms with post-weaning mortality.
abstract: Influenza A virus (IAV) and porcine reproductive and respiratory syndrome virus (PRRSV) are among the most important pathogens affecting pigs worldwide. Their effect on post-weaning mortality can be substantial and may be potentiated by other concomitant factors. Here, the objective was to evaluate the association between IAV and PRRSV infection at weaning with post-weaning mortality observed in wean-to-finish farms in order to better quantify the full impact of their presence in breeding herds. IAV and PRRSV presence was assessed by real time reverse transcription (RRT)-PCR on oral fluid samples from suckling piglets in nine sow farms. Production data from 177 batches of growing pigs weaned one week before/after IAV and PRRSV testing were analyzed to measure the association between IAV and/or PRRSV test results and mortality recorded for a given batch through the use of Bayesian mixed effects negative binomial multivariable regression model. The model accounted for potential confounders such as flow, date at weaning, days on feed and batch size. A statistically important association between IAV (incidence ratio (IR)=1.18, 95% posterior probability interval 1.15-1.21) and PRRSV (IR=1.41, 95% PPI 1.30-1.52) with post-weaning mortality was detected, with season and number of days on feed also associated. Our results suggest that infection with IAV or PRRSV in the pre-weaning period is associated with an increase in post-weaning mortality. This association should be taken into consideration when measuring the impact of IAV and PRRSV in breeding herds.
authors.affiliation: Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA. Electronic address: jalvarez@umn.edu.
authors.forename: Julio
authors.initials: J
authors.lastname: Alvarez
authors.affiliation: Department of General and Systemic Pathology, Veterinary Faculty, National University of Rosario, Casilda, Argentina.
authors.forename: Javier
authors.initials: J
authors.lastname: Sarradell
authors.affiliation: Pipestone Veterinary Services, Pipestone, MN, USA.
authors.forename: Barry
authors.initials: B
authors.lastname: Kerkaert
authors.affiliation: Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Bandyopadhyay
authors.affiliation: Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Torremorell
authors.affiliation: Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Morrison
authors.affiliation: Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
authors.forename: Andres
authors.initials: A
authors.lastname: Perez
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D015994:Incidence; D009980:Influenza A virus / Q000302:isolation & purification*; D015146:Midwestern United States / Q000453:epidemiology; D015999:Multivariate Analysis; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000401:mortality / Q000662:veterinary* / Q000821:virology; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology* / Q000401:mortality / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000302:isolation & purification*; D015995:Prevalence; D012044:Regression Analysis; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000401:mortality / Q000821:virology; D014886:Weaning
keywords: Bayesian modeling; Influenza A virus; Porcine reproductive and respiratory syndrome virus; Post-weaning mortality; Swine