dengue

HABITAT SEGREGATION OF DENGUE VECTORS ALONG AN URBAN ENVIRONMENTAL GRADIENT

Cox, J, Grillet, ME, Ramos, OM, Ammador, M, et al. Habitat
segregation of dengue vectors along an urban environmental
gradient. Am J Trop Med Hyg 2007; 76:820–826.

Abstract: 
Differential distributions of Aedes aegypti and Ae. mediovittatus (potential inter-epidemic dengue vector) and other mosquitoes colonizing bamboo pots in San Juan, Puerto Rico were studied along an urban-rural gradient. City regions (urban, suburban, and rural) and landscape elements within regions (forest [F], low-density housing [LDH], and high-density housing [HDH]) were identified using satellite imagery. Aedes species extensively overlapped in LDH of urban, suburban, and rural areas. Mosquito species showed their high specificity for landscape elements (96.6% correct classification by discriminant analysis); absence of Ae. mediovittatus in HDH or absence of Ae. aegypti in forests were the main indicator variables. The gradient was explained using a canonical correspondence analysis, which showed the association of Ae. aegypti with HDH in urban areas, Culex quinquefasciatus with LDH in suburbs, and Ae. mediovittatus and other native mosquitoes (Cx. antillummagnorum, Toxorhynchites portoricencis) with less disturbed habitats (forests, LDH).

Climate influence on dengue epidemics in Puerto Rico

Jury, M., 2008: Climate influences on dengue epidemics in Puerto
Rico. Int. J. Environ. Health Res., 18, 323–334.

Abstract: 
The variability of the insect-borne disease dengue in Puerto Rico was studied in relation to climatic variables in the period 1979–2005. Annual and monthly reported dengue cases were compared with precipitation and temperature data. Results show that the incidence of dengue in Puerto Rico was relatively constant over time despite global warming, possibly due to the offsetting effects of declining rainfall, improving health care and little change in population. Seasonal fluctuations of dengue were driven by rainfall increases from May to November. Year-to-year variability in dengue cases was positively related to temperature, but only weakly associated with local rainfall and an index of El Nin˜ o Southern Oscillation (ENSO). Climatic conditions were mapped with respect to dengue cases and patterns in high and low years were compared. During epidemics, a low pressure system east of Florida draws warm humid air over the northwestern Caribbean. Long-term trends in past observed and future projected rainfall and temperatures were studied. Rainfall has declined slowly, but temperatures in the Caribbean are rising with the influence of global warming. Thus, dengue may increase in the future, and it will be necessary to anticipate dengue epidemics using climate forecasts, to reduce adverse health impacts.
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