title: Scale-free distribution of avian influenza outbreaks.
abstract: Using global case data for the period from 25 November 2003 to 10 March 2007, we construct a network of plausible transmission pathways for the spread of avian influenza among domestic and wild birds. The network structure we obtain is complex and exhibits scale-free (although not necessarily small-world) properties. Communities within this network are connected with a distribution of links with infinite variance. Hence, the disease transmission model does not exhibit a threshold and so the infection will continue to propagate even with very low transmissibility. Consequentially, eradication with methods applicable to locally homogeneous populations is not possible. Any control measure needs to focus explicitly on the hubs within this network structure.
authors.affiliation: Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. ensmall@polyu.edu.hk
authors.forename: Michael
authors.initials: M
authors.lastname: Small
authors.forename: David M
authors.initials: DM
authors.lastname: Walker
authors.forename: Chi Kong
authors.initials: CK
authors.lastname: Tse
mesh_terms: D000818:Animals; D001717:Birds; D004196:Disease Outbreaks; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000302:isolation & purification / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology*; D008962:Models, Theoretical