The global infectious disease burden exceeds several hundred million cases each year, and infectious diseases are estimated to account for one-third of annual human mortality. For many infectious diseases, principally those that are vectorborne, there is a significant amount of data relating diseases incidence to climate or weather factors. With the increasing accumulation of satellite data, a better understanding is emerging of the complex interrelations among weather and climate conditions and the survival and spread of pathogenic microorganisms and disease vectors and hosts.
Annual rainfall and temperature averages are important parameters in the demarcation of bioclimate envelopes within which the occurrence of many infectious diseases is concentrated. These factors also have significant effects on variables, such as vector population size, which are related to disease outbreaks and epidemics. Although more is known about the effects of weather and climate conditions on the prevalence of vectorborne disease, there are important links between these factors and the occurrence of waterborne, airborne, soilborne, and foodborne diseases.
Large-scale weather disturbances like El Niño can have a dramatic impact on the incidence of many infectious diseases, such as malaria and Rift Valley fever. Scientists have discovered numerous connections between the 1991-1995 El Niño and increases in the incidence of diseases, including cholera and hantavirus pulmonary syndrome. El Niño-related increases in sea-surface temperature and sea-surface height in the Bay of Bengal have been associated with a rise in the number of cholera cases in Bangladesh. Recent findings from the 1997-98 El Niño are providing corroborating evidence for a causal relationship between extreme weather events and disease outbreaks.
Better quality and more comprehensive data sets are needed to improve the current understanding of how weather and climate affect the prevalence and occurrence of infectious disease. This information is essential for developing accurate predictive models of disease outbreaks. Research on climate-disease links is interdisciplinary in scope and includes microbiology, epidemiology, ecology, oceanography, climatology, atmospheric sciences, and marine biology. Progress needs to be made in making data sets more accessible to researchers in these and other disciplines.
Rita R. Colwell, Jonathan A. Patz. 1998. Climate, infectious disease and health: an interdisciplinary perspective.
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