Thursday, March 4, 2010

Climate and behavioral change

In recent years, "malaria has been spreading into highland areas of East Africa, Indonesia, Afghanistan, and elsewhere" it was previously unknown. High elevations, low temperature, and temperate rainy seasons prevented malaria from entering these regions before. Now, the deadly disease is contracted locally in these previously malaria-safe environments. Malaria "is on the rise in some parts of the world" partly due to climate change. Other "factors such as migration and land-use changes are likely also at play."

"We assessed...conclusions from both sides and found that evidence for a role of climate in the dynamics is robust," write study authors Luis Fernando Chaves from Emory University and Constantianus Koenraadt of Wageningen University in the Netherlands. "However, we also argue that over-emphasizing a role for climate is misleading for setting a research agenda, even one which attempts to understand climate change impacts on emerging malaria patterns."

"Malaria, a parasitic disease spread to humans by mosquitoes, is common in warm climates of Africa, South America and South Asia." Development and survival of the mosquito and parasite depend on warm temperatures; therefore, "the disease has been spreading to the highlands, and many studies link the spread to global warming. But that conclusion is far from unanimous. Other studies have found no evidence of warming in highland regions, thus ruling out climate change as a driver for highland malaria."

Most studies, which conclude that climate change plays a significant role in highland malaria, tend to be statistically strong. Clearly, climate change does impact the range of malaria endemic regions; however, it may not be the only contributing factor. "What is needed, the researchers say, is a research approach that combines climate with other possible factors."

"Even if trends in temperature are very small, organisms can amplify such small changes and that could cause an increase parasite transmission," a researcher said. "More biological data will improve our overall understanding of malaria and will allow scientists to propose more general and accurate models on the impacts of climate change on malaria transmission."

Some factors contributing to the spread of malaria may be migration and agriculture. People "migrating from lowlands may be introducing the malaria parasite into highland regions. Changes in farming practices may also play a role. Irrigation associated with more intensive farming may be creating more places for mosquitoes to breed."

"The spread of malaria in highlands is of great concern to those who work to contain the disease. But understanding the many factors that influence the spread of highland malaria could help with efforts to control the disease worldwide."

University of Chicago Press Journals (2010, March 4). Climate change one factor in malaria spread. ScienceDaily. Retrieved March 4, 2010, from­ /releases/2010/03/100303162906.htm

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