Diseased finches provide clues to ecology of infectious disease

An eye disease that struck eastern house finches in Maryland in 1994 may help expand scientists' understanding of a number of epidemic diseases in humans, animals and plants.

A project to investigate the ecology of infectious disease is under way. It is being funded by a five-year grant from the National Institutes of Health. This study and related projects will examine how environmental changes such as habitat destruction, global warming and pollution may cause diseases to emerge.

"An unusually large number of new diseases have emerged in the last 20 years or so, not only in humans, but in animals and plants as well," says ecologist Andre Dhondt of the Cornell Laboratory of Ornithology in Ithaca.

He cites as examples AIDS, Ebola, drug-resistant tuberculosis, Mad Cow disease, and other spreading plagues.

"This is probably the first study ever where it has been possible to study in great detail a newly emerging disease in a natural population," Dhondt says.

In the case of the finches, scientists at the University of Georgia and North Carolina State found the birds were infected with a new strain of Mycoplasma gallisepticum, a bacterium that is a common cause of upper respiratory infections in chickens. It had never been seen in songbirds.

"The goal is not to know about house finches and Mycoplasma," Dhondt says. "The goal is to develop a mathematical model that allows us to identify what we need to measure and summarize what we've found."

The model can then be applied to other diseases.

"One of the interesting things about Mycoplasma in house finches is that it has many similarities to AIDS," Dhondt says. "Understanding how we can fight this disease in finches might help us understand how to treat similar epidemics in humans."

The finch infection reduced the eastern house finch population by 60 percent - 180 million birds - within 2 1/2 years.