Lee Hu Suk, Nguyen-Viet Hung, Nam Vu Sinh, Lee Mihye, Won Sungho, Duc Phuc Pham, Grace Delia
International Livestock Research Institute, Regional Office for East and Southeast Asia, Room 301-302, B1 Building, Van Phuc Diplomatic Compound, 298 Kim Ma Street, Ba Dinh District, Hanoi, Vietnam.
Vector Borne Diseases and Training, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
BMC Infect Dis. 2017 Mar 20;17(1):218. doi: 10.1186/s12879-017-2326-8.
In Vietnam, dengue fever (DF) is still a leading cause of hospitalization. The main objective of this study was to evaluate the seasonality and association with climate factors (temperature and precipitation) on the incidences of DF in four provinces where the highest incidence rates were observed from 1994 to 2013 in Vietnam.
Incidence rates (per 100,000) were calculated on a monthly basis from during the study period. The seasonal-decomposition procedure based on loess (STL) was used in order to assess the trend and seasonality of DF. In addition, a seasonal cycle subseries (SCS) plot and univariate negative binomial regression (NBR) model were used to evaluate the monthly variability with statistical analysis. Lastly, a generalized estimating equation (GEE) was used to assess the relationship between monthly incidence rates and weather factors (temperature and precipitation).
We found that increased incidence rates were observed in the second half of each year (from May through December) which is the rainy season in each province. In Hanoi, the final model showed that 1 °C rise of temperature corresponded to an increase of 13% in the monthly incidence rate of DF. In Khanh Hoa, the final model displayed that 1 °C increase in temperature corresponded to an increase of 17% while 100 mm increase in precipitation corresponded to an increase of 11% of DF incidence rate. For Ho Chi Minh City, none of variables were significant in the model. In An Giang, the final model showed that 100 mm increase of precipitation in the preceding and same months corresponded to an increase of 30% and 22% of DF incidence rate.
Our findings provide insight into understanding the seasonal pattern and associated climate risk factors.
在越南，登革热（DF）仍是住院治疗的主要病因。本研究的主要目的是评估1994年至2013年期间越南登革热发病率最高的四个省份登革热发病率的季节性以及与气候因素（温度和降水）的关联。
在研究期间按月计算发病率（每10万人）。使用基于局部加权回归散点平滑法（STL）的季节分解程序来评估登革热的趋势和季节性。此外，使用季节循环子序列（SCS）图和单变量负二项回归（NBR）模型通过统计分析评估月度变异性。最后，使用广义估计方程（GEE）评估月度发病率与天气因素（温度和降水）之间的关系。
我们发现每年下半年（从5月到12月）发病率上升，这是每个省份的雨季。在河内，最终模型显示温度每升高1℃，登革热月度发病率增加13%。在庆和省，最终模型显示温度升高1℃对应发病率增加17%，而降水量增加100毫米对应登革热发病率增加11%。对于胡志明市，模型中的变量均无统计学意义。在安江省，最终模型显示前一个月和当月降水量增加100毫米分别对应登革热发病率增加30%和22%。
我们的研究结果有助于深入了解季节性模式和相关气候风险因素。
