Abstract
BackgroundPigs are mixing vessels for influenza viral reassortment, but the extent of influenza transmission between swine and humans is not well understood.ObjectivesTo assess whether occupational exposure to pigs is a risk factor for human infection with human and swine‐adapted influenza viruses.Methods UK pig industry workers were frequency‐matched on age, region, sampling month, and gender with a community‐based comparison group from the Flu Watch study. HI assays quantified antibodies for swine and human A(H1) and A(H3) influenza viruses (titres ≥ 40 considered seropositive and indicative of infection). Virus‐specific associations between seropositivity and occupational pig exposure were examined using multivariable regression models adjusted for vaccination. Pigs on the same farms were also tested for seropositivity.ResultsForty‐two percent of pigs were seropositive to A(H1N1)pdm09. Pig industry workers showed evidence of increased odds of A(H1N1)pdm09 seropositivity compared to the comparison group, albeit with wide confidence intervals (CIs), adjusted odds ratio after accounting for possible cross‐reactivity with other swine A(H1) viruses (aOR) 25·3, 95% CI (1·4–536·3), P = 0·028.ConclusionThe results indicate that A(H1N1)pdm09 virus was common in UK pigs during the pandemic and subsequent period of human A(H1N1)pdm09 circulation, and occupational exposure to pigs was a risk factor for human infection. Influenza immunisation of pig industry workers may reduce transmission and the potential for virus reassortment.
Highlights
Influenza A viruses can cause significant morbidity and mortality in humans and other animal species and show a high degree of genomic variability and adaptability
We explored whether occupational exposure to pigs was associated with infection with each virus strain through univariable analysis using chi-square (v2) and Fisher’s exact tests
Where an influenza strain was found to be associated with occupational pig exposure, we investigated the possibility of cross-reactivity between that strain and other swine viruses sharing the same haemagglutinin using cross-tabulations with chi-square or Fisher’s exact test as appropriate
Summary
Influenza A viruses can cause significant morbidity and mortality in humans and other animal species and show a high degree of genomic variability and adaptability. They are categorised by subtype based on their main surface glycoproteins, haemagglutinin (HA) and neuraminidase (NA), which determine a range of key properties including antigenicity. Human-adapted viruses in the past century have been those expressing HA subtypes 1, 2, and 3 and NA subtypes 1 and 2. Observations over the past 40–50 years have documented subtypes of viruses A(H1N1), A(H1N2) and A(H3N2) circulating in pigs worldwide and strain variations between Europe, North America and Asia have been noted.. Pigs are mixing vessels for influenza viral reassortment, but the extent of influenza transmission between swine and humans is not well understood
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
