Giuseppe
Emeritus
[Source: PLoS ONE, full text: (LINK). Abstract, edited.]
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Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza?s Seasonality
Wan Yang<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Subbiah Elankumaran<SUP>3</SUP>, Linsey C. Marr<SUP>1</SUP><SUP>*</SUP>
<SUP></SUP>
1 Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, United States of America, 2 Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, United States of America, 3 Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
Abstract
Humidity has been associated with influenza?s seasonality, but the mechanisms underlying the relationship remain unclear. There is no consistent explanation for influenza?s transmission patterns that applies to both temperate and tropical regions. This study aimed to determine the relationship between ambient humidity and viability of the influenza A virus (IAV) during transmission between hosts and to explain the mechanisms underlying it. We measured the viability of IAV in droplets consisting of various model media, chosen to isolate effects of salts and proteins found in respiratory fluid, and in human mucus, at relative humidities (RH) ranging from 17% to 100%. In all media and mucus, viability was highest when RH was either close to 100% or below ~50%. When RH decreased from 84% to 50%, the relationship between viability and RH depended on droplet composition: viability decreased in saline solutions, did not change significantly in solutions supplemented with proteins, and increased dramatically in mucus. Additionally, viral decay increased linearly with salt concentration in saline solutions but not when they were supplemented with proteins. There appear to be three regimes of IAV viability in droplets, defined by humidity: physiological conditions (~100% RH) with high viability, concentrated conditions (50% to near 100% RH) with lower viability depending on the composition of media, and dry conditions (<50% RH) with high viability. This paradigm could help resolve conflicting findings in the literature on the relationship between IAV viability in aerosols and humidity, and results in human mucus could help explain influenza?s seasonality in different regions.
Citation: Yang W, Elankumaran S, Marr LC (2012) Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza?s Seasonality. PLoS ONE 7(10): e46789. doi:10.1371/journal.pone.0046789
Editor: Man-Seong Park, College of Medicine, Hallym University, Republic of Korea
Received: June 12, 2012; Accepted: September 6, 2012; Published: October 3, 2012
Copyright: ? 2012 Yang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This research was partially supported by the National Science Foundation under grant number CBET-0547107. No additional external funding was received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: lmarr@vt.edu
-Wan Yang<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Subbiah Elankumaran<SUP>3</SUP>, Linsey C. Marr<SUP>1</SUP><SUP>*</SUP>
<SUP></SUP>
1 Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, United States of America, 2 Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, United States of America, 3 Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
Abstract
Humidity has been associated with influenza?s seasonality, but the mechanisms underlying the relationship remain unclear. There is no consistent explanation for influenza?s transmission patterns that applies to both temperate and tropical regions. This study aimed to determine the relationship between ambient humidity and viability of the influenza A virus (IAV) during transmission between hosts and to explain the mechanisms underlying it. We measured the viability of IAV in droplets consisting of various model media, chosen to isolate effects of salts and proteins found in respiratory fluid, and in human mucus, at relative humidities (RH) ranging from 17% to 100%. In all media and mucus, viability was highest when RH was either close to 100% or below ~50%. When RH decreased from 84% to 50%, the relationship between viability and RH depended on droplet composition: viability decreased in saline solutions, did not change significantly in solutions supplemented with proteins, and increased dramatically in mucus. Additionally, viral decay increased linearly with salt concentration in saline solutions but not when they were supplemented with proteins. There appear to be three regimes of IAV viability in droplets, defined by humidity: physiological conditions (~100% RH) with high viability, concentrated conditions (50% to near 100% RH) with lower viability depending on the composition of media, and dry conditions (<50% RH) with high viability. This paradigm could help resolve conflicting findings in the literature on the relationship between IAV viability in aerosols and humidity, and results in human mucus could help explain influenza?s seasonality in different regions.
Citation: Yang W, Elankumaran S, Marr LC (2012) Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza?s Seasonality. PLoS ONE 7(10): e46789. doi:10.1371/journal.pone.0046789
Editor: Man-Seong Park, College of Medicine, Hallym University, Republic of Korea
Received: June 12, 2012; Accepted: September 6, 2012; Published: October 3, 2012
Copyright: ? 2012 Yang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This research was partially supported by the National Science Foundation under grant number CBET-0547107. No additional external funding was received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: lmarr@vt.edu
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