Ecological factors associated with dengue fever in a central highlands Province, Vietnam

Abstract

BackgroundDengue is a leading cause of severe illness and hospitalization in Vietnam. This study sought to elucidate the linkage between climate factors, mosquito indices and dengue incidence.MethodsMonthly data on dengue cases and mosquito larval indices were ascertained between 2004 and 2008 in the Dak Lak province (Vietnam). Temperature, sunshine, rainfall and humidity were also recorded as monthly averages. The association between these ecological factors and dengue was assessed by the Poisson regression model with adjustment for seasonality.ResultsDuring the study period, 3,502 cases of dengue fever were reported. Approximately 72% of cases were reported from July to October. After adjusting for seasonality, the incidence of dengue fever was significantly associated with the following factors: higher household index (risk ratio [RR]: 1.66; 95% confidence interval [CI]: 1.62-1.70 per 5% increase), higher container index (RR: 1.78; 95% CI: 1.73-1.83 per 5% increase), and higher Breteau index (RR: 1.57; 95% CI: 1.53-1.60 per 5 unit increase). The risk of dengue was also associated with elevated temperature (RR: 1.39; 95% CI: 1.25-1.55 per 2°C increase), higher humidity (RR: 1.59; 95% CI: 1.51-1.67 per 5% increase), and higher rainfall (RR: 1.13; 95% CI: 1.21-1.74 per 50 mm increase). The risk of dengue was inversely associated with duration of sunshine, the number of dengue cases being lower as the sunshine increases (RR: 0.76; 95% CI: 0.73-0.79 per 50 hours increase).ConclusionsThese data suggest that indices of mosquito and climate factors are main determinants of dengue fever in Vietnam. This finding suggests that the global climate change will likely increase the burden of dengue fever infection in Vietnam, and that intensified surveillance and control of mosquito during high temperature and rainfall seasons may be an important strategy for containing the burden of dengue fever.

Hot spot detection and spatio-temporal dynamics of dengue in Queensland, Australia

“…These results are also consistent with those of the studies conducted in other tropical/sub-tropical environments. For example, some studies in Vietnam found that dengue was most prevalent in the wet season (Cuong, 2011, Pham et al, 2011, Toan, 2013. C= Cluster (n) = number of SLAs; *= Primary cluster; Sec = Secondary cluster; R= Radius; O=Observed cases; E=Expected cases; RR=Relative risk; LLR= Log-likelihood ratio Table 4: Space-time clusters of dengue identified using spatial scan test statistic…”

Mathematical assessment of the role of temperature and rainfall on mosquito population dynamics

“…Numerous mathematical models have been designed and used to assess the impact of climate change and seasonality on the transmission dynamics of mosquito-borne diseases, such as malaria (Agusto et al 2015;Ebi et al 2005;Jaenisch and Patz 2002;Mordecai et al 2012;Paaijmans et al 2009), dengue (Chen et al 2010;Hales et al 2002;Pham et al 2011;Wu et al 2009;Yang et al 2011), chikungunya (Fischer et al 2013;Meason and Paterson 2014) and WNv (Abdelrazec et al 2015;Wang et al 2011). For instance, such models allow for the determination of parameters, or variables, that influences the life-cycle of the mosquitoes (Ahumada et al 2004;Cailly et al 2012;Tran et al 2013).…”

Household survey of container–breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia

“…Evidence also exist that the seasonal abundance of dengue vectors are positively correlated with the seasonality of dengue fever activity [18,19] . Besides temperature and humidity [20] , precipitations have been reported influential to dengue vectors' distribution and abundance [21,22] .…”