Swine Workers and Swine Influenza Virus Infections

University of Iowa College of Public Health, Iowa City, Iowa, USA.
Emerging infectious diseases (Impact Factor: 6.75). 01/2008; 13(12):1871-8. DOI: 10.3201/eid1312.061323
Source: PubMed


In 2004, 803 rural Iowans from the Agricultural Health Study were enrolled in a 2-year prospective study of zoonotic influenza transmission. Demographic and occupational exposure data from enrollment, 12-month, and 24-month follow-up encounters were examined for association with evidence of previous and incident influenza virus infections. When proportional odds modeling with multivariable adjustment was used, upon enrollment, swine-exposed participants (odds ratio [OR] 54.9, 95% confidence interval [CI] 13.0-232.6) and their nonswine-exposed spouses (OR 28.2, 95% CI 6.1-130.1) were found to have an increased odds of elevated antibody level to swine influenza (H1N1) virus compared with 79 nonexposed University of Iowa personnel. Further evidence of occupational swine influenza virus infections was observed through self-reported influenza-like illness data, comparisons of enrollment and follow-up serum samples, and the isolation of a reassortant swine influenza (H1N1) virus from an ill swine farmer. Study data suggest that swine workers and their nonswine-exposed spouses are at increased risk of zoonotic influenza virus infections.

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Available from: Troy Mccarthy, Oct 06, 2015
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    • "SIV is a primary agent that may allow entry of other pathogens into the host (Easterday and Van Reeth, 2006). It also represents a zoonotic risk for people who are in close contact with pigs (Gray et al., 2007; Lopez-Robles et al., 2012). "
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    ABSTRACT: The aim of this study was to provide an overview of the epidemiological status of swine influenza viruses in pigs from northwestern Mexico in 2008-2009. A serological and molecular survey was conducted in 150 pigs from 15 commercial farms in Sonora, Mexico (northwestern region of Mexico). The serological data showed that 55% of the sera were positive for the H1N1 subtype, 59% for the H3N2 subtype, and 38% for both subtypes. Overall, 16.6% (25/150) of the samples were positive for type A influenza by qRT-PCR. The phylogenetic analysis of the H1 viruses circulating in northwestern Mexico were grouped into cluster α, from five other clusters previously described. The influenza virus H1 circulating in northwestern Mexico showed 97-100% identity at the nucleotide level among them, 89% identity with other North American strains, 88% with strains from central Mexico, and 85% with the pandemic A/H1N1p2009 virus. Meanwhile, a closer relationship with some influenza viruses from North America (97% nucleotide identity) was found for H3 subtype. In conclusion, our results demonstrated a high circulation of strains similar to those observed in the North American linage among commercial farms in northwestern Mexico, involving of a different lineage virus different to the influenza pandemic of 2009.
    Veterinary Microbiology 05/2014; 172(1-2). DOI:10.1016/j.vetmic.2014.05.017 · 2.51 Impact Factor
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    • "Transmission of influenza viruses from pigs to humans has been reported occasionally, but most cases result in mild infections rarely resulting in death ( Robinson et al. 2007, Howden et al. 2009, Yassine et al. 2009, Adeola et al. 2010, Song et al. 2010, Forgie et al. 2011, CDC 2012, Gray et al. 2012, Williamson et al. 2012). Swine workers and their family members are at increased risk of contracting swine influenza virus infections ( Olsen et al. 2002, Myers et al. 2006, Gray et al. 2007, Robinson et al. 2007, Yassine et al. 2009, Beaudoin et al. 2012, CDC 2012, Wong et al. 2012). In this study, we were unable to document human flu-like illnesses during the period of sample collection. "
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    ABSTRACT: Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.
    Memórias do Instituto Oswaldo Cruz 08/2013; 108(5):548-53. DOI:10.1590/0074-0276108052013003 · 1.59 Impact Factor
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    • "We found our results in concordance with the mentioned studies, only for the H3N2 virus. In agreement with a previous report (Gray et al., 2007), vaccination appeared as a protective factor [OR 0.22, 95% (CI) 0.07–0.70]. The results of our study are the first evidence of SIV transmission and risk factors among swine workers and pigs in México. "
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    ABSTRACT: A cross-sectional study was conducted to evaluate the transmission of swine influenza through occupational exposure and to assess some risk factors for zoonotic transmission in workers from commercial farms in Mexico. Seroprevalence to swine influenza subtypes was determined by hemagglutinin inhibition assay and was higher in exposed (E), in comparison with unexposed (UE) participants (P<0.05). Percentages of seropositivity between UE and E were 28.57% and 19.35% to A/NewCaledonia/20/99 (H1N1), 68.25% and 33.87% to A/Panama/2001/99-like (H3N2), 1.58% and 12.9% to A/Sw/England/163266/87 (H3N2), respectively. No antibodies were detected against A/Sw/Wisconsin/238/97 (H1N1) in the UE subjects, and only 3.22% were positive in the E group (P<0.05). A significant association between elevated antibody titres to swine influenza virus (SIV) H3N2 and the exposition to swine [OR 3.05, 95% (CI) 1.65-5.64] and to geographic location [OR 8.15, 95% (CI) 1.41-47.05] was found. Vaccination appeared as a protective factor [OR 0.05, 95% (CI) 0.01-0.52]. Farms with high number of breeding herd were associated with increased anti-SIV antibodies in the E group [OR 3.98, 95% (CI) 1.00-15.86]. These findings are relevant and support the evidence of zoonoses in swine farms and point out the need to implement preventive measures to diminish the occurrence of the disease and the potential emergence of pathogenic reassortant strains.
    Transboundary and Emerging Diseases 08/2011; 59(2):183-8. DOI:10.1111/j.1865-1682.2011.01250.x · 2.94 Impact Factor
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