title: Influenza transmission during extreme indoor conditions in a low-resource tropical setting.
abstract: Influenza transmission occurs throughout the planet across wide-ranging environmental conditions. However, our understanding of the environmental factors mediating transmission is evaluated using outdoor environmental measurements, which may not be representative of the indoor conditions where influenza is transmitted. In this study, we examined the relationship between indoor environment and influenza transmission in a low-resource tropical population. We used a case-based ascertainment design to enroll 34 households with a suspected influenza case and then monitored households for influenza, while recording indoor temperature and humidity data in each household. We show that the indoor environment is not commensurate with outdoor conditions and that the relationship between indoor and outdoor conditions varies significantly across homes. We also show evidence of influenza transmission in extreme indoor environments. Specifically, our data suggests that indoor environments averaged 29 °C, 18 g/kg specific humidity, and 68 % relative humidity across 15 transmission events observed. These indoor settings also exhibited significant temporal variability with temperatures as high as 39 °C and specific and relative humidity increasing to 22 g/kg and 85 %, respectively, during some transmission events. However, we were unable to detect differences in the transmission efficiency by indoor temperature or humidity conditions. Overall, these results indicate that laboratory studies investigating influenza transmission and virus survival should increase the range of environmental conditions that they assess and that observational studies investigating the relationship between environment and influenza activity should use caution using outdoor environmental measurements since they can be imprecise estimates of the conditions that mediate transmission indoors.
authors: Department of Geographical and Sustainability Sciences, University of Iowa, 316 Jessup Hall, Iowa City, IA, 52242, USA. james-tamerius@uiowa.edu.
authors: James
authors: J
authors: Tamerius
authors: Sustainable Sciences Institute, Managua, Nicaragua.
authors: Sergio
authors: S
authors: Ojeda
authors: Department of Geography and Program in Public Health, Florida State University, Tallahassee, FL, USA.|Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
authors: Christopher K
authors: CK
authors: Uejio
authors: Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors: Jeffrey
authors: J
authors: Shaman
authors: Sustainable Sciences Institute, Managua, Nicaragua.
authors: Brenda
authors: B
authors: Lopez
authors: Sustainable Sciences Institute, Managua, Nicaragua.
authors: Nery
authors: N
authors: Sanchez
authors: Department of Geography and Program in Public Health, Florida State University, Tallahassee, FL, USA.|Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
authors: Aubree
authors: A
authors: Gordon
mesh_terms: D004279:DNA, Viral / Q000032:analysis; D004777:Environment; D006798:Housing; D006801:Humans; D006813:Humidity; D009980:Influenza A virus / Q000235:genetics; D007251:Influenza, Human / Q000635:transmission*; D009527:Nicaragua; D013696:Temperature; D014329:Tropical Climate
chemical_list: D004279:DNA, Viral