title: Environmental role in influenza virus outbreaks.
abstract: The environmental drivers of influenza outbreaks are largely unknown. Despite more than 50 years of research, there are conflicting lines of evidence on the role of the environment in influenza A virus (IAV) survival, stability, and transmissibility. With the increasing and looming threat of pandemic influenza, it is important to understand these factors for early intervention and long-term control strategies. The factors that dictate the severity and spread of influenza would include the virus, natural and acquired hosts, virus-host interactions, environmental persistence, virus stability and transmissibility, and anthropogenic interventions. Virus persistence in different environments is subject to minor variations in temperature, humidity, pH, salinity, air pollution, and solar radiations. Seasonality of influenza is largely dictated by temperature and humidity, with cool-dry conditions enhancing IAV survival and transmissibility in temperate climates in high latitudes, whereas humid-rainy conditions favor outbreaks in low latitudes, as seen in tropical and subtropical zones. In mid-latitudes, semiannual outbreaks result from alternating cool-dry and humid-rainy conditions. The mechanism of virus survival in the cool-dry or humid-rainy conditions is largely determined by the presence of salts and proteins in the respiratory droplets. Social determinants of heath, including health equity, vaccine acceptance, and age-related illness, may play a role in influenza occurrence and spread.
authors.affiliation: Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061; email: kumarans@vt.edu.
authors.forename: Harini
authors.initials: H
authors.lastname: Sooryanarain
authors.forename: Subbiah
authors.initials: S
authors.lastname: Elankumaran
mesh_terms: D000818:Animals; D001717:Birds; D002980:Climate; D004195:Disease Models, Animal; D004196:Disease Outbreaks; D004777:Environment; D054884:Host-Pathogen Interactions; D006801:Humans; D006813:Humidity; D009980:Influenza A virus / Q000472:pathogenicity / Q000502:physiology*; D005585:Influenza in Birds / Q000453:epidemiology / Q000635:transmission / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission / Q000821:virology; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D012621:Seasons; D013696:Temperature
keywords: environment; influenza viruses; outbreaks; transmission