The Epidemic Characteristics Of Dengue Fever In Guangzhou, 2014 And The Effects Of Climate, Density Of Mosquito In The Occurrence Of Dengue Fever In Guangzhou

Objective To understand the population distribution of dengue fever and the time- spatial distribution characteristics and their change tendencies, to investigate the effects of climate, density of mosquito in the occurrence of dengue fever in order to provide scientific basis for dengue fever prevention and control.Methods The information about dengue fever incidence, climate, demography, density of mosquito of Guangzhou, 2014 and dengue fever incidence information between 2006 and 2013 were collected systematically. Descriptive analysis was used to analyze the incidence rate and its time, spatial and population distributions. The contrasts with before and other countries and regions were also conducted. Space-time scan statistics was used for the analysis of the time- spatial distribution characteristics and their change tendencies. Correlation analysis was used for univariate analysis of the relationship between the mosquito-borne, climate factors and the onset of dengue fever. GAM(generalized additive model) was used for prove the effects of climate, density of mosquito in the occurrence of dengue fever. Statistical softwares that used in this study were R(version 3.1.2), SPSS(version 20.0) and Arc GIS(version 10.1).Results 1. Totally 37340 local cases were reported in Guangzhou, 2014(including 16010 laboratory confirmed cases and 21330 clinical confirmed cases), in which 5 fatal cases were reported, and the incidence rate was 290.83 per hundred thousand, the mortality was 1.34 per 10 thousand, respectively. 2. The group of under five years old had the least incidence rate of dengue fever(147.2 per hundred thousand), while The group of beyond 80 years old owned the highest(555.3 per hundred thousand), The incidence rate showed an increase tendency with age( tendency χ2=392.9, p<0.01). The incidence rate of women was higher than the men’s(271.7 per hundred thousand vs. 312.4 per hundred thousand). 3. The peak of in incidence was focus on September and October, in which period 34184 cases were reported. The median duration of street outbreak was 94 days. 11.9%(19/159)streets experience the outbreak within 50 days, the duration of street outbreak was 50-100, below 100 in 4.0%(70/159)and 44.0(70/159)streets, respectively. 4. All of the 12 districts had dengue cases and the incidence rates were between 16.76 – 530.47 per hundred thousand, in which Baiyun district owned the highest(530.47 per hundred thousand) while Conghua owned the lowest( 16.76 per hundred thousand) and the incidence rates of 5 districts that called Baiyun, Liwan, Yuexiu, Haizhu and Huangpu were beyond the average level of Guangzhou, which was 528.84,488.68, 406.71, 379.66 and 315.19 per hundred thousand, respectively. 5. The clustering time of dengue fever in Guangzhou, 2014 was between September 11 and October 21, and the spatial cluster was distribution in Luogang District, Tianhe District, Huangpu District, Baiyun District and Yuexiu District with 17885 cases in the time-spatial cluster, and the expected cases were 1853 and the RR was 17.61(p<0.01), no secondary cluster was observed. The primary clusters were observed in Baiyun, Liwan, Yuexiu, Haizhu, Panyu, Tianhe, Luogang and Huangpu, while seceondary clusters in Conghua and Nansha and non-clusters in Zengcheng and Huadu Between 2006 to 2013. 6. The mean, low and high of daliy temperature, relative humity were all related to the incidence of dengue fever(p<0.05) and the r were 0.232、0.295、-0.125and-0.272 respectively. BI and SSI were related with the incidence of dengue fever after one one month, and the r were 0.609 and 0.518, respectively. 7. The GAM analysis showed that the mean, low and high of daliy temperature, relative humity can influence the incidence of dengue fever and the RR were 1.017(1.014~1.02), 1.018(1.015~1.022), 1.011(1.008~1.013), 1.006(1.003~1.008) and 1.190(1.188~1.191), respectively. The lag time of highest and lowest temperatures and BI that influenced dengue fever were 4 weeks, while the lag was 3 week of relative humidity and rainfall. The rise of per 1°C in highest temperature increases 1.7% risk of dengue fever, while 1.8% for lowest temperature. The rise of per 1% of relative humidity can increase 1.1% risk of dengue fever, while the rise of 1mm increases 0.6% risk of dengue fever, and 1 increase of BI increases 19% risk of dengue fever.Conclusions 1.The outbreak of dengue fever in Guangzhou,2014 showed a rapidly increase tendency on the basis of 2013. On the boundary of October, the incidence of dengue fever in Guangzhou, 2014 suffered an increase and decline between August and November. 2.The epidemic characters of dengue fever in Guangzhou didn’t consisted with the criteria of endemic. 3.Dengue fever epidemic presented a time-spatial clustering characteristics and climate, density of mosquito affected the incidence of dengue fever. 4.In the future, the prevention and control of dengue fever should combine with these features.