Assessment of seasonality of influenza in swine using field submissions to a diagnostic laboratory in Ontario between 2007 and 2012

Influenza and Other Respiratory Viruses

Zvonimir Poljak¹  Susy Carman² 

[1] Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada;Animal Health Laboratory, University of Guelph, Guelph, ON, Canada

关键词: Diagnostic;    influenza;    monitoring;    seasonality;    swine;   

DOI  :  10.1111/irv.12248

来源: Wiley

【 摘 要 】

Abstract

Background

Seasonality of any infectious disease is important for its control and monitoring. While influenza seasonality in people has been evaluated extensively, this question has not been studied well in swine populations.

Objective

The goal of this study was to investigate seasonality of influenza in swine, using diagnostic submissions to a diagnostic laboratory.

Methods

Two thousand seven hundred and eleven virological tests within 685 submissions and 5471 serological tests within 193 submissions in Ontario swine between 2007 and 2012 were included in the study and converted to total monthly number of virological and serological submissions, and the number of positive submissions. Data were analyzed by time-series decomposition, fixed-effect Poisson, random-effect Poisson regression with month as uncorrelated and correlated random effects.

Results

All approaches identified seasonality in virological submissions (P < 0·02) with peak in January and April, and a trough in July, but were not able to detect seasonality of influenza-positive virological submissions (P > 0·13). Seasonality of positive serological submissions was identified only if independence between months was assumed (P < 0·03). Almost 50% of serological submissions had evidence of exposure to H3N2 and H1N1.

Conclusions

Thus, this study identified evidence of seasonality in influenza-like disease in swine herds, but not in circulation of influenza virus. Evidence of seasonality in exposure to influenza was dependent on assumptions of between-month correlation. High exposure to H3N2 and H1N1 subtypes warrants more detailed investigation of within-herd influenza virus circulation. The study provides initial insight into seasonality of influenza in swine and should be followed with herd-level studies.

【 授权许可】

CC BY   
© 2014 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.