Will Bugs Creep North as Climate Heats?
Onome Akpogheneta
With predictions of temperatures rising by the end of this century, what will happen to the bugs that carry disease when the world warms? Will diseases of the Southern Hemisphere become more prevalent in these countries? Will the insects carry their disease burdens to the North? For many statistical models the effect of climate change on vector-borne diseases are real causes for concern. But perhaps predictions about climate change and disease migration support actions to limit climate change rather than highlight the most likely of disease-spread scenarios.
It has been widely hypothesized that global warming will bring new permissive environments for biting insects that can carry viral, bacterial, helminth and protozoal diseases. These insects include mosquitoes, ticks, sandflies, snails and blackflies; all are sensitive to climatic changes. Mosquito-borne diseases including malaria, dengue, viral encephalitides, West Nile fever, filariasis and yellow fever are some which have caused climate change associated concerns and investigations in recent years. Fears persist that newly resident infected mosquitoes could harbour and import diseases to regions and countries from which they have been absent or eradicated. The result could be greater disease prevalence and more disease outbreaks within countries of the Global South, as well as northern migration of disease epidemics. Fears have grown that climate change disease migration could become a global health threat in the 21st century.
While fears have grown, reliable evidence to reflect long-term climate change effects on mosquito-borne diseases has not kept pace. "Detailed scientific evidence remains scanty," says Peter Byass in an 2009 article in Global Health Action magazine; he considers that "entomological studies [are] expensive [and] not seen as high priority for disease surveillance." It is precisely because of "scanty" historical and longitudinal data on vector habitats and associated disease outbreaks that climate change predictions will likely be unreliable for vector-borne diseases. Predictions for simplistic long-term correlations should be made with disclaimers; there's simply not enough data to prove cause and effect.
