Malaria climbs into warmer highlands

AP: In one New Guinea hilltop village the message was rooted deep in lore: If you hunt in the valley below and sleep there overnight, evil spirits will possess you, you'll become sick, and you'll die. It was a homespun kind of malaria control in the highlands of this western Pacific island, long free of the disease-bearing mosquitoes that plague the hot and humid nights of its lowlands, said Dr. Ivo Mueller, a lead scientist at the Papua New Guinea Institute of Medical Research. As the Earth warms, however, "malaria epidemics in the highlands are now basically happening every year," Mueller said.

…"What is going to be the burden on the health care infrastructure of poor, developing countries?" asked Hannah Reid, of London's International Institute for Environment and Development, opening a panel session Wednesday in Bali on the health impacts of climate change. Forecasting those impacts can be controversial, both politically and scientifically.

In Washington this October, for example, The Associated Press reported that the Bush administration, which opposes mandatory international action to rein in warming, expurgated pages discussing such negative health effects from a U.S. official's congressional testimony. At the technical level, researchers in poorer nations like Papua New Guinea often cannot find the reliable health statistics — or, sometimes, historical temperature readings — they need to reach scientific conclusions.

"Not having quality health data that spans many decades makes the long-term assessment of climate change impact on health rather difficult," Dr. Jonathan Patz, an international expert on health and climate, said in a telephone interview from his office at the University of Wisconsin.

…International health authorities say more than 1 million people, mostly African children, die each year of malaria, caused by a parasite transmitted by the bite of the female anopheles mosquito. Tens of millions more suffer chronically from the debilitating disease.

…The Intergovernmental Panel on Climate Change, a U.N. network of climate scientists, has long projected that mosquito-borne tropical diseases would spread to new areas that grew warmer. But in its latest reports, issued this year, the IPCC panel was cautious about more specific projections. "Despite the known causal links between climate and malaria transmission dynamics, there is still much uncertainty about the potential impact of climate change on malaria at local and global scales," it concluded. Malaria's range may even contract in such areas as the Amazon, which is expected to grow drier as the world warms, scientists say.

As Mueller noted, factors beyond temperature and humidity can influence malaria's spread: population movements, deforestation, preventive health measures and failing health systems, among other elements. But the malaria researcher said the bottom line is clear.

"There's no question," he said. "If you put climate change into the equation and the climate becomes more favorable, the mosquitoes' numbers go up and you're going to have more and more transmission."