Abstract
Influenza is a costly disease for pig producers and understanding its epidemiology is critical to control it. In this study, we aimed to estimate the herd-level prevalence and seasonality of influenza in breed-to-wean pig farms, evaluate the correlation between influenza herd-level prevalence and meteorological conditions, and characterize influenza genetic diversity over time. A cohort of 34 breed-to-wean farms with monthly influenza status obtained over a 5-year period in piglets prior to wean was selected. A farm was considered positive in a given month if at least one oral fluid tested influenza positive by reverse transcriptase polymerase chain reaction. Influenza seasonality was assessed combining autoregressive integrated moving average (ARIMA) models with trigonometric functions as covariates. Meteorological conditions were gathered from local land-based weather stations, monthly aggregated and correlated with influenza herd-level prevalence. Influenza herd-level prevalence had a median of 28% with a range from 7 to 57% and followed a cyclical pattern with levels increasing during fall, peaking in both early winter (December) and late spring (May), and decreasing in summer. Influenza herd-level prevalence was correlated with mean outdoor air absolute humidity (AH) and temperature. Influenza genetic diversity was substantial over time with influenza isolates belonging to 10 distinct clades from which H1 delta 1 and H1 gamma 1 were the most common. Twenty-one percent of farms had three different clades co-circulating over time, 18% of farms had two clades, and 41% of farms had one clade. In summary, our study showed that influenza had a cyclical pattern explained in part by air AH and temperature changes over time, and highlighted the importance of active surveillance to identify high-risk periods when strategic control measures for influenza could be implemented.
Highlights
Influenza A virus (IAV) is an economically significant pathogen in pig populations and it has been associated with increased mortality [1], increased feed conversion, and decreased daily weight gain in finishing pigs [2, 3]
BTW farms play a crucial role in influenza epidemiology because piglets can unnoticeably maintain, diversify, and transmit IAV at weaning when they are moved to grow-finish farms [5,6,7]
There is some evidence that IAV infections in pigs are more common in the colder months [8,9,10] but, in general, information on herd-level prevalence and seasonal distribution of influenza in BTW farms is limited and it is unclear whether seasonality is observed in piglets, given that piglets are born almost daily and for the most part, they are housed in mechanically controlled environments
Summary
Influenza A virus (IAV) is an economically significant pathogen in pig populations and it has been associated with increased mortality [1], increased feed conversion, and decreased daily weight gain in finishing pigs [2, 3]. IAV is part of Influenza Prevalence Seasonality in Pigs the porcine respiratory disease complex in pigs together with porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae, and porcine circovirus type 2 (PCV2). There is some evidence that IAV infections in pigs are more common in the colder months [8,9,10] but, in general, information on herd-level prevalence and seasonal distribution of influenza in BTW farms is limited and it is unclear whether seasonality is observed in piglets, given that piglets are born almost daily and for the most part, they are housed in mechanically controlled environments
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
