title: Quantification of bird-to-bird and bird-to-human infections during 2013 novel H7N9 avian influenza outbreak in China.
abstract: From February to May, 2013, 132 human avian influenza H7N9 cases were identified in China resulting in 37 deaths. We developed a novel, simple and effective compartmental modeling framework for transmissions among (wild and domestic) birds as well as from birds to human, to infer important epidemiological quantifiers, such as basic reproduction number for bird epidemic, bird-to-human infection rate and turning points of the epidemics, for the epidemic via human H7N9 case onset data and to acquire useful information regarding the bird-to-human transmission dynamics. Estimated basic reproduction number for infections among birds is 4.10 and the mean daily number of human infections per infected bird is 3.16*10-5 [3.08*10-5, 3.23*10-5]. The turning point of 2013 H7N9 epidemic is pinpointed at April 16 for bird infections and at April 9 for bird-to-human transmissions. Our result reveals very low level of bird-to-human infections, thus indicating minimal risk of widespread bird-to-human infections of H7N9 virus during the outbreak. Moreover, the turning point of the human epidemic, pinpointed at shortly after the implementation of full-scale control and intervention measures initiated in early April, further highlights the impact of timely actions on ending the outbreak. This is the first study where both the bird and human components of an avian influenza epidemic can be quantified using only the human case data.
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan; Center for Infectious Disease Education and Research, China Medical University, Taichung, Taiwan.
authors.forename: Ying-Hen
authors.initials: YH
authors.lastname: Hsieh
authors.affiliation: Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada; Centre for Disease Modelling, York University, Toronto, Ontario, Canada.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada; Centre for Disease Modelling, York University, Toronto, Ontario, Canada; Department of Mathematics, Harbin Institute of Technology, Harbin, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Fang
authors.affiliation: Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Mathematics, Shanghai University, Shanghai, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Lou
mesh_terms: D000818:Animals; D001717:Birds / Q000821:virology; D002681:China; D004196:Disease Outbreaks; D058872:Epidemics; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D015047:Zoonoses / Q000453:epidemiology* / Q000635:transmission / Q000821:virology