Disease

Abstract

Global warming and the resulting progressive change in climate zones has allowed the spread of vector-borne diseases into ecosystems that were cool and inhospitable to the vectors in the past but are now accepting of them as climates have become warmer and wetter. For example, mosquitoes have expanded their range to warmer higher latitudes and higher altitudes with the result that malaria and dengue fever have spread into regions that were previously free of them. The same is true of the tsetse fly and the encephalitis virus it carries, deer and the disease causing ticks they carry, and rodents bearing flea-borne disease viruses. If there is no mobility for vectors out of the regions where such diseases originate, the threats to other global locations are minimal. However, with mobility, vectors can carry diseases far distances. For example, in the middle ages rats bearing fleas that carried the plague arrived in Europe from the Orient on ships and originated a pandemic that caused the deaths of a third of the European population. In areas with increased rainfall and/or inadequate access to sanitation (e.g., regions in Africa and Asia), water-borne diseases will continue to subject hundreds of millions to diarrheal diseases and possibly epidemics from cholera and typhoid.