Dust Storms and Pestilence

Here's a disquieting article about previously unsuspected mode of disease transmission: Dust Storms Overseas Carry Contaminants to U.S.--Scientists Study Whether Diseases Are Also Transported by Doug Struck, Washington Post, February 6, 2008.

Now, with NASA satellites and sampling by researchers around the world, scientists know that great billowing clouds of dust waft over the oceans in the upper atmosphere, arriving in North America from deserts in Africa and Asia.

Researchers have also found that the dust clouds contain not only harmful minerals and industrial pollutants, but also living organisms: bacteria, fungus and viruses that may transmit diseases to humans. Some say an alarming increase in asthma in children in the Caribbean is the consequence of dust blown from Africa, and predict they will find similar connections in the Southeast and Northwest United States.

Scientists are beginning to look at these dust clouds as possible suspects in transcontinental movement of diseases such as influenza and SARS in humans, or foot-and-mouth disease in livestock. Until recently, epidemiologists had looked at people, animals and products as carriers of the diseases.

"We are just beginning to accumulate the evidence of airborne dust implications on human health," said William A. Sprigg, a climate expert at the University of Arizona. "Until now, it's been like the tree falling in the forest. Nobody heard, so nobody knew it was there."

The World Meteorological Organization, a science arm of the United Nations, is alarmed enough to set up a global warning system to track the moving clouds of dust and to alert those in the path. Sprigg is heading the project.

....Even natural minerals can be harmful to humans, and dust-borne particles have been linked to annual meningitis outbreaks in Africa and silicosis lung disease in Kazakhstan and North Africa. The Dust Bowl storms of the 1930s in the United States brought graphic descriptions of choking sediment getting into the lungs of people and felling livestock.

But the advent of satellite images gave scientists a sobering look at how even faraway storms can reach us.