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The Rise of Dengue Fever in Non-Endemic Argentina
Carbajo, A.E., Cardo, M.V. and Vezzani, D. 2012. Is temperature the main cause of dengue rise in non-endemic countries? The case of Argentina. International Journal of Health Geographics 11: 10.1186/1476-072X-11-26.

The authors write that "dengue cases have increased during the last decades, particularly in non-endemic areas, and Argentina was no exception in the southern transmission fringe." They also indicate that although temperature rise has been blamed for this geographical expansion of the disease, "human population growth, increased travel and inefficient vector control may also be implicated." Thus, they evaluated the relative contributions of geographic, demographic and climatic variables to the recent spreading of the disease.

What was done
Carbajo et al. divided their study into two halves - a first decade that included the re-emergence of the disease, and a second decade that included several epidemics - wherein "annual dengue risk was modelled by a temperature-based mechanistic model as annual days of possible transmission," and where "the spatial distribution of dengue occurrence was modelled as a function of the output of the mechanistic model, climatic, geographic and demographic variables for both decades."

What was learned
The three Argentine researchers report that dengue spatial occurrence "was positively associated with days of possible transmission, human population number, population fall and distance to water bodies." And when considered separately, they state that "the classification performance of demographic variables was higher than that of climatic and geographic variables."

What it means
Although useful to estimate annual transmission risk, Carbajo et al. conclude that temperature "does not fully describe the distribution of dengue occurrence at the country scale," and that "when taken separately, climatic variables performed worse than geographic or demographic variables," while acknowledging that "a combination of the three types was best for this task."

Reviewed 8 May 2013