That, coupled with the isolation and well-defined food webs of the islands, makes them a good system to study what ecological factors affect the presence of the virus.
"The prevalence of disease was found to be a function of ecological variables that humans can measure," Orrock says. "What this illustrates is that if you know just a few things, you can have a reasonable shot of predicting the disease prevalence."
Working with Brian Allan from the University of Illinois at Urbana-Champaign and Charles Drost from the U.S. Geological Survey's Southwest Biological Science Center, Orrock mined an existing dataset.
The data were collected on the Channel Islands shortly after the Four Corners outbreak, to look for relationships between biological and physical island characteristics and the prevalence of Sin Nombre on each of the eight islands.
The researchers found that 79 percent of the variation in disease prevalence among the islands could be explained by a single factor--average annual precipitation.
Adding in the physical characteristics of the islands and the number of predators accounted for a total of 98 percent of the variation.
Higher infection rates among Channel Island deer mice were strongly associated with more precipitation, larger island area and fewer predator species.
The strong effect of precipitation levels highlights potential links between changing climate regimes and human health.
The results also suggest that more diverse predator populations could help keep animal-borne diseases in check--an important lesson as top predators like wolves and bears increasingly disappear from ecosystems due to habitat loss and conflicts with humans.
The authors note that future studies should use experimental methods and examine larger systems to evaluate the generality of
|Contact: Cheryl Dybas|
National Science Foundation