Climate and Dengue Transmission: Evidence and Implications

Abstract

Background: Climate influences dengue ecology by affecting vector dynamics, agent development, and mosquito/human interactions. Although these relationships are known, the impact climate change will have on transmission is unclear. Climate-driven statistical and process-based models are being used to refine our knowledge of these relationships and predict the effects of projected climate change on dengue fever occurrence, but results have been inconsistent.Objective: We sought to identify major climatic influences on dengue virus ecology and to evaluate the ability of climate-based dengue models to describe associations between climate and dengue, simulate outbreaks, and project the impacts of climate change.Methods: We reviewed the evidence for direct and indirect relationships between climate and dengue generated from laboratory studies, field studies, and statistical analyses of associations between vectors, dengue fever incidence, and climate conditions. We assessed the potential contribution of climate-driven, process-based dengue models and provide suggestions to improve their performance.Results and Discussion: Relationships between climate variables and factors that influence dengue transmission are complex. A climate variable may increase dengue transmission potential through one aspect of the system while simultaneously decreasing transmission potential through another. This complexity may at least partly explain inconsistencies in statistical associations between dengue and climate. Process-based models can account for the complex dynamics but often omit important aspects of dengue ecology, notably virus development and host–species interactions.Conclusion: Synthesizing and applying current knowledge of climatic effects on all aspects of dengue virus ecology will help direct future research and enable better projections of climate change effects on dengue incidence.Citation: Morin CW, Comrie AC, Ernst KC. 2013. Climate and dengue transmission: evidence and implications. Environ Health Perspect 121:1264–1272; http://dx.doi.org/10.1289/ehp.1306556

Climate variation drives dengue dynamics

“…However, although precipitation appears to be a key driver of the shorter-term changes (this study), urban landscape features, such as recently constructed artificial lakes in Guangzhou, appear to be key drivers of longerterm trends (21). As in other dengue epidemic areas (11,22,23), we find a strong link between dengue incidence and density of Aedes mosquitoes, the vectors of dengue. These findings support the utility of vector population control through, for example, pesticides, Wolbachia bacteria infection of mosquitoes, or habitat measures, for reducing the intensity of dengue outbreaks (24,25).…”

Exploratory Analysis of Dengue Fever Niche Variables within the Río Magdalena Watershed

“…The watershed is in close proximity to the equator, indicating a warmer climate, and well within the currently-documented latitude range of the Aedes aegypti mosquito [8]. The elevation of the watershed's mountain boundaries should naturally isolate the Aedes aegypti vector from external areas, providing a study area with limited external influence [41,42]. Due to its location on the western side of South America, it is also influenced by El Niño/La Niña seasonal variations.…”

“…Due predominantly to the mountainous terrain, the Magdalena River watershed has a large temperature range which exceeds both the minimum and maximum temperature thresholds (which has been found to extend from 14 • C and 24 • C, respectively, depending on location or study parameters [3,28]). This provides more influence on the mosquito's ability to thrive [3,18,28], and impacts the extrinsic incubation period and duration of the gonotrophic cycle [30,41], than has been witnessed in previous studies. As noted, the temperature range variables were based off three annual assessments, so the results do not necessarily document the actual temperature limits of the Aedes aegypti.…”

“…However, these results do not necessarily contradict previous work, as they still loaded within the principal components of Stage 2. The lower than expected importance of urban LCLU and population in this study suggests the need for future studies to investigate contributory urban attributes, particularly if using different spatial or temporal resolutions [1,3,17,41]. For example measures of local density, urban heat island, or water storage potential variables could be investigated rather than an individual LULC urban variable.…”

Mosquito Economics in Laboratory: a retrospective study in a tertiary care hospital in India

“…It has become a significant health problem due to expanding geographic distribution with climate change and gradual evolution from an epidemic with long year's interval into an epidemic with seasonal trend [8,9]. Vector development and survival rates are affected by temperature, precipitation and humidity although the associations of environmental factors are not consistently described in literature [10,11].…”