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Local and global effects of climate on dengue transmission in Puerto Rico.

Johansson MA, Dominici F, Glass GE - PLoS Negl Trop Dis (2009)

Bottom Line: The abundance and the transmission potential of Ae. aegypti are influenced by temperature and precipitation.While there is strong biological evidence for these effects, empirical studies of the relationship between climate and dengue incidence in human populations are potentially confounded by seasonal covariation and spatial heterogeneity.These results suggest the importance of temperature and precipitation in the transmission of dengue viruses and suggest a reason for their spatial heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: Dengue Branch, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico. mjohansson@cdc.gov

ABSTRACT
The four dengue viruses, the agents of dengue fever and dengue hemorrhagic fever in humans, are transmitted predominantly by the mosquito Aedes aegypti. The abundance and the transmission potential of Ae. aegypti are influenced by temperature and precipitation. While there is strong biological evidence for these effects, empirical studies of the relationship between climate and dengue incidence in human populations are potentially confounded by seasonal covariation and spatial heterogeneity. Using 20 years of data and a statistical approach to control for seasonality, we show a positive and statistically significant association between monthly changes in temperature and precipitation and monthly changes in dengue transmission in Puerto Rico. We also found that the strength of this association varies spatially, that this variation is associated with differences in local climate, and that this relationship is consistent with laboratory studies of the impacts of these factors on vector survival and viral replication. These results suggest the importance of temperature and precipitation in the transmission of dengue viruses and suggest a reason for their spatial heterogeneity. Thus, while dengue transmission may have a general system, its manifestation on a local scale may differ from global expectations.

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Related in: MedlinePlus

Local short-term associations between weather and dengue incidence.Points represent the estimated proportional increase in dengue incidence for an increase in monthly temperature (1°C) or precipitation (1 mm) in each municipality at each lag (months). All lagged weather variables were included in the regression model simultaneously. Municipalities are ordered by mean average temperature or precipitation, low to high (left to right). Black bars indicate the 95% credible interval for each estimate based on 1,000 models, one for each conditional simulation of weather data.
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pntd-0000382-g001: Local short-term associations between weather and dengue incidence.Points represent the estimated proportional increase in dengue incidence for an increase in monthly temperature (1°C) or precipitation (1 mm) in each municipality at each lag (months). All lagged weather variables were included in the regression model simultaneously. Municipalities are ordered by mean average temperature or precipitation, low to high (left to right). Black bars indicate the 95% credible interval for each estimate based on 1,000 models, one for each conditional simulation of weather data.

Mentions: In the distributed lag model including temperature at lags of 0, 1, and 2 months and precipitation at lags of 1 and 2 months, monthly variation in temperature was positively associated with monthly variation in dengue incidence in most municipalities (Figure 1). The global association (average short-term association across all municipalities) was positive and statistically significant at all three lags. Short-term associations were significant for monthly maximum and minimum temperature but weaker than those observed for average monthly temperature. Monthly variation in cumulative precipitation was significantly associated with monthly variation in dengue incidence in some, but not all, municipalities at lags of 1 and 2 months (Figure 1). Globally, this association was significantly positive only after accounting for local effect modification by long-term climate. These findings were robust to the addition of further temperature and precipitation lags.


Local and global effects of climate on dengue transmission in Puerto Rico.

Johansson MA, Dominici F, Glass GE - PLoS Negl Trop Dis (2009)

Local short-term associations between weather and dengue incidence.Points represent the estimated proportional increase in dengue incidence for an increase in monthly temperature (1°C) or precipitation (1 mm) in each municipality at each lag (months). All lagged weather variables were included in the regression model simultaneously. Municipalities are ordered by mean average temperature or precipitation, low to high (left to right). Black bars indicate the 95% credible interval for each estimate based on 1,000 models, one for each conditional simulation of weather data.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2637540&req=5

pntd-0000382-g001: Local short-term associations between weather and dengue incidence.Points represent the estimated proportional increase in dengue incidence for an increase in monthly temperature (1°C) or precipitation (1 mm) in each municipality at each lag (months). All lagged weather variables were included in the regression model simultaneously. Municipalities are ordered by mean average temperature or precipitation, low to high (left to right). Black bars indicate the 95% credible interval for each estimate based on 1,000 models, one for each conditional simulation of weather data.
Mentions: In the distributed lag model including temperature at lags of 0, 1, and 2 months and precipitation at lags of 1 and 2 months, monthly variation in temperature was positively associated with monthly variation in dengue incidence in most municipalities (Figure 1). The global association (average short-term association across all municipalities) was positive and statistically significant at all three lags. Short-term associations were significant for monthly maximum and minimum temperature but weaker than those observed for average monthly temperature. Monthly variation in cumulative precipitation was significantly associated with monthly variation in dengue incidence in some, but not all, municipalities at lags of 1 and 2 months (Figure 1). Globally, this association was significantly positive only after accounting for local effect modification by long-term climate. These findings were robust to the addition of further temperature and precipitation lags.

Bottom Line: The abundance and the transmission potential of Ae. aegypti are influenced by temperature and precipitation.While there is strong biological evidence for these effects, empirical studies of the relationship between climate and dengue incidence in human populations are potentially confounded by seasonal covariation and spatial heterogeneity.These results suggest the importance of temperature and precipitation in the transmission of dengue viruses and suggest a reason for their spatial heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: Dengue Branch, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico. mjohansson@cdc.gov

ABSTRACT
The four dengue viruses, the agents of dengue fever and dengue hemorrhagic fever in humans, are transmitted predominantly by the mosquito Aedes aegypti. The abundance and the transmission potential of Ae. aegypti are influenced by temperature and precipitation. While there is strong biological evidence for these effects, empirical studies of the relationship between climate and dengue incidence in human populations are potentially confounded by seasonal covariation and spatial heterogeneity. Using 20 years of data and a statistical approach to control for seasonality, we show a positive and statistically significant association between monthly changes in temperature and precipitation and monthly changes in dengue transmission in Puerto Rico. We also found that the strength of this association varies spatially, that this variation is associated with differences in local climate, and that this relationship is consistent with laboratory studies of the impacts of these factors on vector survival and viral replication. These results suggest the importance of temperature and precipitation in the transmission of dengue viruses and suggest a reason for their spatial heterogeneity. Thus, while dengue transmission may have a general system, its manifestation on a local scale may differ from global expectations.

Show MeSH
Related in: MedlinePlus