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[This corrects the article DOI: 10.1371/journal.pone.0194647.].

We report on a study conducted in Guangdong Province, China, to characterize behaviors and perceptions associated with transmission of pathogens with pandemic potential in highly exposed human populations at the animal-human interface. A risk factor/exposure survey was administered to individuals with high levels of exposure to wildlife. Serological testing was performed to evaluate prior infection with several wildlife viral pathogens. Follow up serology was performed on a subset of the cohort as well as close contacts of individuals. 1,312 individuals were enrolled in the study. Contact with a wide range of wildlife species was reported in both occupational and occasional contexts. The overall proportion of individuals seropositive to any of the tested wildlife pathogens was approximately 4.0%. However, persons employed as butchers demonstrated a seropositivity of 9.0% to at least one pathogen of interest. By contrast, individuals working as hunters had lower rates of seropositivity. Among the study population, a number of other behaviors showed correlation with seropositivity, including contact with particular wildlife species such as field rats. These results demonstrate the need to further explore zoonotic risks of particular activities regarding wildlife contact, and to better understand risks of persons working as butchers with wildlife species.

Zoonotic transmission of influenza A virus (IAV) between swine and workers in swine production facilities may play a role in the emergence of novel influenza strains with pandemic potential. Guidelines to prevent transmission of influenza to swine workers have been developed but there is a need for evidence-based decision-making about protective measures such as respiratory protection. A mathematical model was applied to estimate the risk of occupational IAV exposure to swine workers by contact and airborne transmission, and to evaluate the use of respirators to reduce transmission.  The Markov model was used to simulate the transport and exposure of workers to IAV in a swine facility. A dose-response function was used to estimate the risk of infection. This approach is similar to methods previously used to estimate the risk of infection in human health care settings. This study uses concentration of virus in air from field measurements collected during outbreaks of influenza in commercial swine facilities, and analyzed by polymerase chain reaction.  It was found that spending 25 min working in a barn during an influenza outbreak in a swine herd could be sufficient to cause zoonotic infection in a worker. However, this risk estimate was sensitive to estimates of viral infectivity to humans. Wearing an excellent fitting N95 respirator reduced this risk, but with high aerosol levels the predicted risk of infection remained high under certain assumptions.  The results of this analysis indicate that under the conditions studied, swine workers are at risk of zoonotic influenza infection. The use of an N95 respirator could reduce such risk. These findings have implications for risk assessment and preventive programs targeting swine workers. The exact level of risk remains uncertain, since our model may have overestimated the viability or infectivity of IAV. Additionally, the potential for partial immunity in swine workers associated with repeated low-dose exposures or from previous infection with other influenza strains was not considered. Further studies should explore these uncertainties.

To assess the behavior and precautions that swine workers take during suspected influenza outbreaks in swine, six commercial swine farms in the Midwest U.S. region were visited when influenza outbreaks were suspected in herds during the fall/winter of 2012-2013. Use of personal protective equipment (PPE) and type of task performed by swine workers were recorded based on farm representative reports. Between one to two workers were working on the day of each visit and spent approximately 25 minutes performing work-related tasks that placed them in close contact with the swine. The most common tasks reported were walking the aisles (27%), handling pigs (21%), and handling equipment (21%). The most common PPE were boots (100%), heavy rubber gloves (75%), and dedicated nondisposable clothing (74%). Use of N95 respirators was reported at three farms. Hand hygiene practices were common in most of the farms, but reportedly performed for only 20% to 25% of tasks.

Indirect transmission of influenza A virus (IAV) in swine is poorly understood and information is lacking on levels of environmental exposure encountered by swine and people during outbreaks of IAV in swine barns. We characterized viral load, viability and persistence of IAV in air and on surfaces during outbreaks in swine barns. IAV was detected in pigs, air and surfaces from five confirmed outbreaks with 48% (47/98) of oral fluid, 38% (32/84) of pen railing and 43% (35/82) of indoor air samples testing positive by IAV RT-PCR. IAV was isolated from air and oral fluids yielding a mixture of subtypes (H1N1, H1N2 and H3N2). Detection of IAV RNA from air was sustained during the outbreaks with maximum levels estimated between 7 and 11 days from reported onset. Our results indicate that during outbreaks of IAV in swine, aerosols and surfaces in barns contain significant levels of IAV potentially representing an exposure hazard to both swine and people.

Background: Swine workers may play a key role in transmission of zoonotic influenza viruses. At the same time, little is known about the extent and effectiveness of influenza prevention programs for these at-risk workers., Objectives: To characterize practices and attitudes regarding zoonotic influenza transmission among swine workers in Romania., Methods: We conducted a convenience survey of swine workers in Romania. The confidential survey included questions about awareness of zoonotic influenza risk, work tasks performed, flu vaccination status, and reported influenza-like illness., Results: A total of 103 workers at seven farms completed the survey. The percentage of workers reporting concern about either contracting influenza from pigs or giving influenza to pigs was 78% and 70%, respectively. Although 60% of workers reported having a sick-leave policy at work, only 7% of workers reported receiving seasonal influenza vaccination during the past flu season. Only 5% of the workers reported flu-like illness during the past year while 3% of workers reported that pigs appeared sick with influenza over the same time period. The majority of workers reported using protective overalls and rubber boots during swine work, with lower rates of use of gloves. Reported use of respiratory protection was rare, and use of any personal protective equipment did not differ when pigs appeared ill., Conclusions: Despite awareness and concern regarding zoonotic influenza, Romanian swine workers report low rates of influenza vaccine or respiratory protection. As part of global pandemic influenza preparedness, enhanced prevention programs for swine workers should address such gaps., (© 2013 Blackwell publishing Ltd.)