Author
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JETTEN, THEO - NETHERLANDS |
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Focks, Dana |
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Submitted to: American Journal of Tropical Medicine and Hygiene
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/26/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Many if not most scientists who study the world's climate believe that global temperatures will rise between 1.0 and 3.5 degree C (about 2 to 6 degree F) during the next century. Concern has been expressed that warming will adversely affect agriculture and probably result in rising ocean levels permanently flooding coastal areas around the world. More recently, however, groups like the Intergovernmental Panel on Climate Change (IPCC) and the World Health Organization have concluded that the most serious health consequence will be an increase in diseases transmitted between people by the bite of insects, diseases like malaria, encephalitis, and yellow fever. Using mathematics and computers, scientists from USDA and the Netherlands have shown that the most important viral disease transmitted by mosquitoes, dengue hemorrhagic fever, currently found throughout the tropics, will be significantly influenced by the expected climate warming. An important conclusion of the study was that the geographical range of dengue will expand out of the tropics and into temperate areas. Dengue is also expected to move into high-altitude cities such as Mexico City where it is currently too cool to allow transmission. The final conclusion was that a serious form of dengue involving shock and hemorrhage in children will become much more common in the tropics and sub-tropics. Technical Abstract: This paper quantifies the expected impact of global climate warming on the intensity and distribution of dengue transmission throughout the world. The method uses an expression of vectorial capacity modified to reflect the role of temperature on development and survival of the vector and virus. The traditional vectorial capacity expression was used to derive an estimator of the number of adult female vectors required to just maintain the virus in an endemic state. In this expression, temperature influences adult survival, the lengths of the gonotrophic cycle and the extrinsic incubation period of the virus in the vector, and vector size. We validated the technique by successfully comparing model projections and the observed spatial, temporal, and altitudinal distribution of dengue using current climate in 5 cities that are endemic or have had epidemics in the past. Our results indicate that the current warming projection of the IPCC of 2 degree C by the end of the next century can be expected to result in an increase in the latitudinal and altitudinal range of dengue; the duration of the transmission season will also increase in temperate locations as well. We explain how climate-related in increases in the incidence of dengue haemorrhagic fever and shock syndrome among infants and adolescents. |
