title: Can human movements explain heterogeneous propagation of dengue fever in Cambodia?
abstract: BACKGROUND
  Determining the factors underlying the long-range spatial spread of infectious diseases is a key issue regarding their control. Dengue is the most important arboviral disease worldwide and a major public health problem in tropical areas. However the determinants shaping its dynamics at a national scale remain poorly understood. Here we describe the spatial-temporal pattern of propagation of annual epidemics in Cambodia and discuss the role that human movements play in the observed pattern.
  
  
  RESULTS
  We used wavelet phase analysis to analyse time-series data of 105,598 hospitalized cases reported between 2002 and 2008 in the 135 (/180) most populous districts in Cambodia. We reveal spatial heterogeneity in the propagation of the annual epidemic. Each year, epidemics are highly synchronous over a large geographic area along the busiest national road of the country whereas travelling waves emanate from a few rural areas and move slowly along the Mekong River at a speed of ~11 km per week (95% confidence interval 3-18 km per week) towards the capital, Phnom Penh.
  
  
  CONCLUSIONS
  We suggest human movements - using roads as a surrogate - play a major role in the spread of dengue fever at a national scale. These findings constitute a new starting point in the understanding of the processes driving dengue spread.
authors.affiliation: Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
authors.forename: Magali
authors.initials: M
authors.lastname: Teurlai
authors.forename: Rekol
authors.initials: R
authors.lastname: Huy
authors.forename: Bernard
authors.initials: B
authors.lastname: Cazelles
authors.forename: Raphaël
authors.initials: R
authors.lastname: Duboz
authors.forename: Christophe
authors.initials: C
authors.lastname: Baehr
authors.forename: Sirenda
authors.initials: S
authors.lastname: Vong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002160:Cambodia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000453:epidemiology*; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D019371:Topography, Medical; D014171:Transients and Migrants; D055815:Young Adult