title: Global patterns in seasonal activity of influenza A/H3N2, A/H1N1, and B from 1997 to 2005: viral coexistence and latitudinal gradients.
abstract: Despite a mass of research on the epidemiology of seasonal influenza, overall patterns of infection have not been fully described on broad geographic scales and for specific types and subtypes of the influenza virus. Here we provide a descriptive analysis of laboratory-confirmed influenza surveillance data by type and subtype (A/H3N2, A/H1N1, and B) for 19 temperate countries in the Northern and Southern hemispheres from 1997 to 2005, compiled from a public database maintained by WHO (FluNet). Key findings include patterns of large scale co-occurrence of influenza type A and B, interhemispheric synchrony for subtype A/H3N2, and latitudinal gradients in epidemic timing for type A. These findings highlight the need for more countries to conduct year-round viral surveillance and report reliable incidence data at the type and subtype level, especially in the Tropics.
authors: Center for Infectious Disease Dynamics, Department of Biology, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America. bsf143@psu.edu
authors: Brian S
authors: BS
authors: Finkelman
authors: Cécile
authors: C
authors: Viboud
authors: Katia
authors: K
authors: Koelle
authors: Matthew J
authors: MJ
authors: Ferrari
authors: Nita
authors: N
authors: Bharti
authors: Bryan T
authors: BT
authors: Grenfell
mesh_terms: D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D009975:Orthomyxoviridae / Q000145:classification*; D012621:Seasons