Choi Youngjo, Tang Choon Siang, McIver Lachlan, Hashizume Masahiro, Chan Vibol, Abeyasinghe Rabindra Romauld, Iddings Steven, Huy Rekol
World Health Organization, Phnom Penh, Cambodia.
Australian National University, Canberra, Australia.
BMC Public Health. 2016 Mar 8;16:241. doi: 10.1186/s12889-016-2923-2.
Dengue viruses and their mosquito vectors are sensitive to their environment. Temperature, rainfall and humidity have well-defined roles in the transmission cycle. Therefore changes in these conditions may contribute to increasing incidence. The aim of this study was to examine the relationship between weather factors and dengue incidence in three provinces in Cambodia, in order to strengthen the evidence basis of dengue control strategies in this high-burden country.
We developed negative binomial models using monthly average maximum, minimum, mean temperatures and monthly cumulative rainfall over the period from January 1998 to December 2012. We adopted piecewise linear functions to estimate the incidence rate ratio (IRR) between dengue incidence and weather factors for simplicity in interpreting the coefficients. We estimated the values of parameters below cut-points defined in terms of the results of sensitivity tests over a 0-3 month lagged period.
Mean temperature was significantly associated with dengue incidence in all three provinces, but incidence did not correlate well with maximum temperature in Banteay Meanchey, nor with minimum temperature in Kampong Thom at a lag of three months in the negative binomial model. The monthly cumulative rainfall influence on the dengue incidence was significant in all three provinces, but not consistently over a 0-3 month lagged period. Rainfall significantly affected the dengue incidence at a lag of 0 to 3 months in Siem Reap, but it did not have an impact at a lag of 2 to 3 months in Banteay Meanchey, nor at a lag of 2 months in Kampong Thom.
The association between dengue incidence and weather factors also apparently varies by locality, suggesting that a prospective dengue early warning system would likely be best implemented at a local or regional scale, rather than nation-wide in Cambodia. Such spatial down-scaling would also enable dengue control measures to be better targeted, timed and implemented.
登革病毒及其蚊媒对环境敏感。温度、降雨和湿度在传播循环中具有明确作用。因此，这些条件的变化可能导致发病率上升。本研究旨在探讨柬埔寨三个省份天气因素与登革热发病率之间的关系，以加强这个高负担国家登革热防控策略的证据基础。
我们利用1998年1月至2012年12月期间的月平均最高温度、最低温度、平均温度和月累计降雨量建立了负二项式模型。为便于解释系数，我们采用分段线性函数来估计登革热发病率与天气因素之间的发病率比（IRR）。我们根据0至3个月滞后期间敏感性测试结果定义的切点以下的参数值进行估计。
在所有三个省份，平均温度均与登革热发病率显著相关，但在负二项式模型中，班迭棉吉省的发病率与最高温度相关性不佳，磅通省在滞后三个月时发病率与最低温度相关性也不佳。月累计降雨量对所有三个省份的登革热发病率均有显著影响，但在0至3个月的滞后期间并非始终如此。降雨在暹粒省滞后0至3个月时对登革热发病率有显著影响，但在班迭棉吉省滞后2至三个月时没有影响，在磅通省滞后2个月时也没有影响。
登革热发病率与天气因素之间的关联显然也因地区而异，这表明前瞻性登革热预警系统可能最好在柬埔寨的地方或区域层面实施，而非全国范围。这种空间尺度缩小还将使登革热防控措施能够更好地靶向、定时和实施。
