Environmental Factors

Climate change=More disease?The prospect that the globe will warm up due to increased concentrations of greenhouse gases in the atmosphere sends causes concern to specialists in mosquito-borne diseases. The greenhouse effect is the warming caused by the reflection carbon dioxide back to the Earth. The existence and activity of mosquitoes and mosquito-borne diseases is strongly linked to temperature. In Zimbabwe, for example, the prevalence of malaria is determined by altitude, which in turn determines temperature.

The carbon dioxide concentration is rising steadily each year, largely due to burning fossil fuels and to a lesser extent land changes like tree removal. Within the last couple years, an international group of scientists warned that the warming seems to have begun. The average warming is predicted to range from 1 degree to 3.5 degree C by year 2100.

But global warming may not just cause mosquitoes to proliferate; it may also allow malaria to spread. The malaria parasites cannot develop below the 16 degree C winter isotherm (line on a map connecting points with the same temperature). But if, as predicted, global warming raises winter temperatures more than summer ones, we could see a dramatic expansion of range for malaria.

The effect of global warming on dengue is no more encouraging, according to a recent journal article: “Slightly higher temperatures within the range of mosquito viability lead to more infectious mosquitoes that bite more frequently.