Can Human Movements Explain Heterogeneous Propagation of Dengue Fever in Cambodia?

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. methods and findings: 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. © 2012 teurlai et al.