Ecology helps stymie diseases
By Lori M. Quillen
For the Poughkeepsie Journal
Lyme thrives in suburban forest patches
From West Nile virus and Ebola to Sudden Oak Death, emerging infectious diseases threaten human health, wildlife, livestock, agriculture and forests. Once established, infectious diseases are economic and ecological burdens that can, in some cases, cause irreversible damage.
Understanding, and ultimately preventing, emerging infectious disease depends on increased dialogue among professionals on the front lines. A three-day conference at the Institute of Ecosystem Studies in May provided a much-needed cross-disciplinary forum for more than 80 ecologists, medical doctors, veterinarians and epidemiologists. The National Science Foundation, Dutchess County and several government and private grants sponsored the conference.
Traditionally, infectious disease has been viewed as a problem best addressed through the use of vaccines or drugs. The diverse group of experts attending the conference explored the role of disease within a big-picture framework — considering the ecological context in which disease epidemics arise and the consequences of disease in ecological systems. One of the main topics discussed at the conference was how ecological systems influence disease dynamics.
"When trying to unravel the infectious diseases of plants and animals, the macroscope of ecologists can provide just as much information as the microscope of microbiologists, veterinarians, and physicians. Infectious diseases exist within an ecological context," Princeton University ecologist Andy Dobson said.
Consider Lyme disease, which infects about 1,000 Dutchess County residents every year. The bacterium that transmits infection to humans is regulated by the presence of black-legged ticks, deer populations and small mammal diversity. Managing diseases with complex life cycles, where pathogens infect multiple host species, requires an understanding of the ecological conditions that promote or inhibit disease.
Animals often source
"Three quarters of emerging diseases — AIDS, marburg, avian flu, etc. — arise in animals, and people become unwitting victims. We need to study disease dynamics in those animal populations," said scientist Felicia Keesing of Bard College and the institute, who organized the conference with institute ecologists Richard Ostfeld and Valerie Eviner.
Animal populations and the diseases they harbor are strongly influenced by environmental changes. Over the past several centuries, the progression of human society has dramatically altered the ecological landscape. From large-scale land modification to the global movement of people, animals, and plants — very few ecosystems can be considered remote or pristine.
These environmental changes can enhance or inhibit the development of certain diseases. For instance, the small forest patches common in suburban landscapes enhance the conditions that foster Lyme disease. There, the white-footed mice and deer that host ticks and harbor the Lyme disease bacterium thrive, but their competitors and predators do not.
A better understanding of disease ecology will enhance our ability to both manage and predict infectious diseases in humans, wildlife, natural plant communities and agriculture.
"Our planet is supporting a population of 6.5 billion, with a projected 9.1 billion in 2050. As borders and ecological boundaries shrink, the divide between theoretical ecology and applied epidemiology is also shrinking," said Whirling Disease Foundation virologist Karl Johnson, who helped discover Ebola and
Hantavirus. "Successfully addressing the infectious diseases of the future will require building a bridge between both sides of the disease equation — epidemiology and ecology."
The dialogue fostered by the conference gave rise to a number of new education and research agendas. These included hiring ecologists in schools of public health, sharing disease ecology findings with health and veterinarian practitioners, developing interdisciplinary graduate programs to train the next generation of medical and ecological professionals, and holding future cross-discipline conferences. Conference proceedings will be published in a book, "Infectious Disease Ecology," available in 2006.
Lori M. Quillen is the public information specialist at the Institute of Ecosystem Studies in Millbrook. She holds a master's degree in conservation biology.
