Reference
Shang, C.-S., Fang, C.-T., Liu, C.-M., Wen, T.-H., Tsai, K.-H. and King, C.-C. 2010. The role of imported cases and favorable meteorological conditions in the onset of dengue epidemics. PLoS 4: e775.
Background
The authors write that dengue -- including dengue fever and dengue hemorrhagic fever -- "is the world's most widely spread mosquito-borne arboviral disease," and they remark that it "threatens more than two-thirds of the world's population," noting that cases of the mosquito-spread disease "are mainly distributed in tropical and subtropical areas in accordance with vector habitats for Aedes aegypti and Ae. albopictus."
What was done
Using logistic and Poisson regression models, Shang et al. recount how they analyzed bi-weekly, laboratory-confirmed dengue cases in Taiwan at their onset dates of illness from 1998 to 2007, in order to "identify correlations between indigenous dengue and imported dengue cases (in the context of local meteorological factors) across different time lags."
What was learned
The six Taiwanese researchers report discovering that "the occurrence of indigenous dengue was significantly correlated with temporally-lagged cases of imported dengue (2-14 weeks), higher temperatures (6-14 weeks), and lower relative humidity (6-20 weeks)," and that "imported and indigenous dengue cases had a significant quantitative relationship in the onset of local epidemics."
What it means
Based on a careful analysis of their findings, Shang et al. conclude that "imported dengue cases are able to initiate indigenous epidemics when appropriate weather conditions are present," or as they state in another place, "imported dengue are able to serve as an initial facilitator, or spark, for domestic epidemics." Therefore, they suggest that "early detection and case management of imported cases through timely surveillance and rapid laboratory-diagnosis may avert large scale epidemics of dengue/dengue hemorrhagic fever," while noting that "meteorology alone does not initiate an epidemic" and stating that "an increase in viremic international travelers has caused global dengue hemorrhagic fever case numbers to surge in the past several decades," which surge is often erroneously claimed by climate alarmists to be due to global warming.