Malaria resurgence in the East African highlands: temperature trends revisited

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 15; pp. 5829 - 5834
• Main Authors: Pascual, M, Ahumada, J.A, Chaves, L.F, Rodo, X, Bouma, M
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 11-04-2006
• Series: From the Cover
• Subjects: Africa, Eastern - epidemiology; air temperature; Altitude; ambient temperature; Aquatic insects; Biological Sciences; Climate; Climate change; Culicidae; Disease transmission; disease vectors; Ecology; Eigenvalues; epidemiology; Greenhouse Effect; highlands; human diseases; Humans; insect vectors; Larvae; Larval development; Malaria; Malaria - epidemiology; mathematical models; Mosquitoes; Mosquitos; Parametric models; Population dynamics; population ecology; Public health; Rain; Statistical analysis; Temperature; Time series; Time series models; Vector-borne diseases; Eastern Africa; Africa, Eastern; East Africa; Africa, East; Africa
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0508929103

The incidence of malaria in the East African highlands has increased since the end of the 1970s. The role of climate change in the exacerbation of the disease has been controversial, and the specific influence of rising temperature (warming) has been highly debated following a previous study reporting no evidence to support a trend in temperature. We revisit this result using the same temperature data, now updated to the present from 1950 to 2002 for four high-altitude sites in East Africa where malaria has become a serious public health problem. With both nonparametric and parametric statistical analyses, we find evidence for a significant warming trend at all sites. To assess the biological significance of this trend, we drive a dynamical model for the population dynamics of the mosquito vector with the temperature time series and the corresponding detrended versions. This approach suggests that the observed temperature changes would be significantly amplified by the mosquito population dynamics with a difference in the biological response at least 1 order of magnitude larger than that in the environmental variable. Our results emphasize the importance of considering not just the statistical significance of climate trends but also their biological implications with dynamical models.