Experts tie diseases to destruction of environment

April 18, 1998
Web posted at: 11:07 p.m. EDT (0307 GMT)

NEW YORK (Reuters) - Experts at a conference Saturday warned of fresh outbreaks of Lyme disease in the United States and tropical diseases across the developing world unless people find better ways to manage the natural environment.

They said new menaces like the AIDS and Ebola viruses and old scourges like malaria were the direct result of interfering with the environment -- destroying forests, wiping out animal species and polluting waters.

Preserving biodiversity, or the variety of different species of animals and plants, is crucial to preventing even bigger epidemics of infectious disease, they said.

Monkeys harbor many viruses

"It is a warning to us when we are too active in these areas," said Dr. Jaap Goudsmit, a top AIDS expert at the University of Amsterdam, who addressed the conference on the value of plants, animals and microbes to human health.

Goudsmit said frightening new viruses threatened to leap from monkeys into people. "There's a lot to come if we continue our current behavior," he said.

He said studies he had done showed monkeys alone harbored many viruses.

"We are actually very worried because we are finding so many viruses in these monkeys that humans are susceptible to," he told the conference, sponsored by the American Museum of Natural History.

People catch the viruses when they eat monkeys or chimpanzees, capture them as pets, or use them in scientific laboratories. And as species of primates are wiped out, the viruses will be forced to seek new hosts, perhaps humans, Goudsmit said.

Lyme disease outbreaks

Deer tick

Richard Ostfeld of the University of Connecticut found outbreaks of Lyme disease in the eastern United States were linked to acorn production in forests and the population of deer mice.

The mice carry the bacterium that causes Lyme disease. They are bitten by ticks, which can then transmit the infection to people. The result is fever, rash and long-lasting health effects.

Ostfeld said his most recent research showed a record acorn harvest in the last year.

"In 1999, because of the life cycle of the tick ... we should see extremely high numbers of cases of Lyme disease unless we can prevent it," Ostfeld said.

Wiping out mice might work but is virtually impossible. What Ostfeld did find was that many animals carried the Lyme agent but only a few transmitted it to ticks. If the bacterium can be spread among a large number of different species of animal, it will be less likely to pass to humans.

"Those ticks that feed on a mouse are highly likely to become infected with Lyme disease," Ostfeld said. "Those ticks that feed on other species are highly unlikely."

States with high numbers of other animals living in the forests, such as rabbits, raccoons and birds, have lower instances of Lyme disease, even though the tick carrier is common in all the states.

'Ecology should be seen as a crucial ally'

The answer seemed obvious to Ostfeld: Encourage many different animals to live in the forest. "Ecology should be seen as a crucial ally ... of the health sciences," he said.

David Molyneux, director of the Liverpool School of Tropical Medicine, said diseases such as leishmaniasis (which causes skin lesions and permanent damage), river blindness, malaria and sleeping sickness had all become more common as people cleared forests.

The mosquitoes and flies that spread such diseases adapted quickly to the new environments, he said. Malaria and sleeping sickness, for example, are spreading to new parts of Africa as rain forests are cleared.

"Now they are adapting rapidly to cocoa and coffee plantations," he said. "Leishmaniasis is closely associated with mining, logging and road-building."

Copyright 1998 Reuters Limited. All rights reserved.

Related stories:

• El Nino winds could stir up wave of tropical diseases - March 12, 1998

Related sites:

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• Centers for Disease Control and Prevention Home Page
• ARS Parasite Biology and Epidemiology Laboratory
• The Lyme Disease Network
• American Lyme Disease Foundation, Inc.
• University of Liverpool / School of Tropical Medicine

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