Does Occupational Exposure to Swine Increase the Risk of Influenza? A Systematic Literature Review

Background Workers who have an occupational exposure to swine may have an increased risk of influenza infection. Objective We conducted a systematic review regarding occupational exposure to swine and influenza infection in humans. Methods We searched articles published within the past ten years at the time of writing, and included original studies that quantified exposures to swine and resulting influenza infections in swine farm workers, including veterinarians. We evaluated the risk of bias of individual studies and the overall quality and strength of the evidence according to the Navigation Guide systematic review methodology. Twelve studies met the inclusion criteria. We rated studies “low”, “probably low”, “probably high”, and “high” risk of bias and rated the overall body of evidence as “moderate” quality with “sufficient” evidence for an association between occupational swine exposure and risk of influenza. Discussion Understanding the risk factors for possible spillover and species jump of influenza is critical to preventing not only illnesses, but also epidemics. Our review found “sufficient evidence” of an association between occupational exposure to swine and increased influenza antibodies, or increased influenza infection. Our results that occupational exposure to swine is associated with an increase in influenza exposure were generally consistent across all twelve studies, except for one. Conclusions We concluded there was sufficient evidence supporting an association between occupational exposure to live swine and increased influenza antibodies and/or infections. Preventing on-farm influenza exposures may reduce the risk for novel viruses entering the broader human population