http://www.cnn.com/2001/TECH/science/07/01/deadly.dust.ap/index.html
CNN.com - African dust brings germs, fungi across the Atlantic - July 1, 2001
African dust brings germs, fungi across the Atlantic
July 1, 2001 Posted: 7:59 PM EDT (2359 GMT)
WASHINGTON (AP) -- Dust from the African deserts is bringing germs and
fungi across the Atlantic.
Researchers who tested samples of the dust collected last summer warn that
"pathogenic microbes associated with dust clouds may pose a risk to
ecosystem and human health."
While wind borne transport of African dust to North and South America long
has been known, scientists thought that few microbes would survive the
trip because of exposure to ultraviolet radiation in the atmosphere.
Researchers now believe the dust clouds themselves block enough of the
light to protect bacteria and other microbes during the 5- to 7-day
journey.
The findings of the group, led by Dale W. Griffin of the U.S. Geological
Survey, are reported in the June issue of the journal Aerobiologia.
About 10 percent of the microbes identified were "opportunistic
pathogens," Griffin said in a telephone interview.
According to Griffin, the microbes are organisms that do not cause disease
in healthy humans, but could affect someone with a compromised immune
system such as AIDS patients, the very old or young and transplant or
cancer patients with suppressed immune systems.
"For most healthy individuals, I don't think it's a problem," said
Griffin, a public health and environmental microbiologist.
In addition, he said, some 25 percent of the microbes were known plant
pathogens that affect elm trees or such crops as peaches, cotton and rice,
he said.
Joseph M. Prospero, director of the Cooperative Institute for Marine and
Atmospheric Studies at the University of Miami said his research in
Barbados also has seen fungi and bacteria associated with African dust.
He said there has been a "very clear association" of sharply increased
incidence of viable fungi and bacteria in African dust arrivals.
"There's no question you can transport a lot of stuff through the
atmosphere," Prospero said in a telephone interview.
When the trajectories of the dust are traced backward, the dust clouds
with the bacteria come only from Africa, while dust arriving from Europe
or North America does not include bacteria, said Prospero, who was not
associated with Griffin's team.
The movement of African dust across the ocean has been increasing in
recent years with the growing drought in Africa. It peaks in June through
October. Large dust arrivals have been measured over roughly 30 percent of
the United States, with about half the volume settling on Florida.