06 August 2008

Climate change, people, and viruses

What effect will climate change on the bugs and viruses that share the human ecosystem?

Climate change is a hot topic, so to speak. We've learnt to expect altered weather patterns in the not-too-distant future, which in turn may lead to extreme heat waves, super storms, flooding and other nasty climate-related events which so far have mainly existed in the minds of Hollywood directors.

These events in themselves pose severe health risks to the human population, but what's even more alarming is the effect the changing climate might have on bugs, viruses and other nasties that share the human ecosystem.

'Climate change's potential influence on the epidemiology of human infectious disease' was the topic of discussion at the University of Cape Town's Darwin Seminar in Cape Town this week. Prof Barry D Schoub, the executive director of the National Institute for Communicable Diseases led the talk.

"The interaction between weather and epidemiology is very complex," explained Schoub. A lot of diseases are climate-related – colds and flu are predominant in the cold winter months, gastrointestinal illness in summer, to name a few of his examples.

Change in weather changes epidemics
For this reason it is obvious to expect changes in epidemiology to go along with the forecasted changes in climate.

Fears of tropical diseases spreading to more temperate regions due to the rise in temperature have been widely publicised. Malaria is a good example. Currently it only occurs in regions hot enough for the vector (the Anopheles mosquito) to survive. If global temperatures rise, regions that have previously been too cold for the Anopheles might become suitable for their survival, and ultimately the spread of malaria.

However, Schoub argues, in reality the situation is much more complex than that. "There are various other non-climatic factors to take into consideration," he said. "Human control factors will play a greater role in limiting disease in the future," Schoub predicts, using the example of how human intervention suppressed the spread of the potentially devastating SARS virus.

"Climate change is not the end of the world, at least not as far as epidemiology is concerned," concluded Schoub. But in the same breath warns that the indirect effects of climate change are very unpredictable, and factors within the control of humans, such as poverty and overcrowding, will have to be tightly regulated to ensure a healthy future for all.

- (Wilma Stassen, Health24, June 2008)

Read more:
Climate to make us sick: WHO
Climate will fuel infections


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