Climate Change Drives Disease To New Territory
Friday, May 5, 2006
TORONTO -- Valere Rommelaere, 82, survived the D-Day invasion in Normandy, but not a mosquito bite. Six decades after the war, the hardy Saskatchewan farmer was bitten by a bug carrying a disease that has spread from the equator to Canada as temperatures have risen. Within weeks, he died from West Nile virus.
Global warming -- with an accompanying rise in floods and droughts -- is fueling the spread of epidemics in areas unprepared for the diseases, say many health experts worldwide. Mosquitoes, ticks, mice and other carriers are surviving warmer winters and expanding their range, bringing health threats with them.
Malaria is climbing the mountains to reach populations in higher elevations in Africa and Latin America. Cholera is growing in warmer seas. Dengue fever and Lyme disease are moving north. West Nile virus, never seen on this continent until seven years ago, has infected more than 21,000 people in the United States and Canada and killed more than 800.
The World Health Organization has identified more than 30 new or resurgent diseases in the last three decades, the sort of explosion some experts say has not happened since the Industrial Revolution brought masses of people together in cities.
"We didn't even know West Nile virus existed here," said Maria Bujak, 63, of Toronto. Her husband, Andrew, contracted the disease in their garden in 2002. He never fully recovered, she said, and died two years later.
"Tropical diseases are here to stay in Canada. We needed our government to wake up and tell us that," said Douglas Elliott, a Toronto lawyer who has brought suit against the Ontario government on behalf of about 40 victims, contending that the government did not do enough to inform the public about the dangers of West Nile.
Scientists have warned for more than a decade that climate change would broaden the range of many diseases. But the warnings were couched in the future, and qualified. The spread of disease is affected by many uncertainties, including unforeseen resistance to antibiotics, failures of public health systems, population movement and yearly climate swings. For that reason, some scientists have been cautious about the link between disease and global warming.
But Paul Epstein, a physician who worked in Africa and is now on the faculty of Harvard Medical School, said that, if anything, scientists weren't worried enough about the problem.
"Things we projected to occur in 2080 are happening in 2006. What we didn't get is how fast and how big it is, and the degree to which the biological systems would respond," Epstein said in an interview in Boston. "Our mistake was in underestimation."
The incremental boost already detected in the Earth's temperature, for example, has expanded the range and activities of disease carriers.
"Insects are exquisitely sensitive to temperature changes," a report prepared by Epstein and others at Harvard's Center for Health and the Global Environment noted in November.
The clearest case for that, according to the report's authors, is in cold areas. The higher elevations of Africa, the Andes mountains in South America and the Alps in Europe are warming at a faster pace than lowlands. As ice caps and glaciers melt, forests inch higher on the mountains, and insects carry diseases from warmer lowlands farther up the slopes.