Featured Research

from universities, journals, and other organizations

Precipitation, predators may be key in ecological regulation of infectious disease

Date:
May 6, 2011
Source:
University of Wisconsin-Madison
Summary:
Ecologists have shown that just three ecological factors -- rainfall, predator diversity, and island size and shape -- can account for nearly all of the differences in infection rates among the eight Channel Islands off the California coast.

Mouse populations on California's Channel Islands, including San Miguel island shown here, harbor high levels of a highly virulent hantavirus called Sin Nombre Virus that can be transmitted to humans. A new study by John Orrock at the University of Wisconsin-Madison and colleagues shows that the prevalence of Sin Nombre in island rodent populations may be correlated with precipitation, island size and shape, and the diversity of predators.
Credit: John Orrock

A little information can go a surprisingly long way when it comes to understanding rodent-borne infectious disease, as shown by a new study led by John Orrock from UW-Madison.

The researchers studied wild deer mouse populations on the Channel Islands off the southern coast of California, which carry a variant of hantavirus called Sin Nombre virus. In their study appearing in the May issue of the journal American Naturalist, they show that just three ecological factors -- rainfall, predator diversity, and island size and shape -- can account for nearly all of the differences in infection rates among the eight islands.

The study also provides some of the first evidence to support a recent hypothesis that predators play an important ecological role in regulating disease -- sometimes known as the "predators are good for your health" hypothesis.

In humans, Sin Nombre virus causes Hantavirus Pulmonary Syndrome, a virulent and often fatal disease. An outbreak of Sin Nombre virus in 1993 in the Four Corners area of the U.S. Southwest killed several people and brought national attention to the disease. Learning what factors control the prevalence and spread of viruses like Sin Nombre within host populations is crucial for understanding the risks of animal-borne diseases.

"The ecological underpinnings of disease prevalence, its dynamics in natural populations, and its transmission from animals to humans are important links that are still being deciphered," says Orrock, an assistant professor of zoology at UW-Madison.

Mouse populations on the Channel Islands have some of the highest rates of Sin Nombre virus ever measured. 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 predictably 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, 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 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 the observed patterns. Nonetheless, the strength of the associations they found on the Channel Islands is striking.

"What's shocking about these data is how tight the relationship is," Orrock says. "Rarely in ecology do you find that one variable will explain 79 percent of the variation in anything. The fact that precipitation does here, and that adding the effects of predator richness and island characteristics explains nearly all the variation in disease prevalence on these eight islands, suggests that we're getting to the heart of some basic ecological principles."


Story Source:

The above story is based on materials provided by University of Wisconsin-Madison. Note: Materials may be edited for content and length.


Journal Reference:

  1. John L. Orrock, Brian F. Allan, Charles A. Drost. Biogeographic and Ecological Regulation of Disease: Prevalence of Sin Nombre Virus in Island Mice Is Related to Island Area, Precipitation, and Predator Richness. The American Naturalist, 2011; 177 (5): 691 DOI: 10.1086/659632

Cite This Page:

University of Wisconsin-Madison. "Precipitation, predators may be key in ecological regulation of infectious disease." ScienceDaily. ScienceDaily, 6 May 2011. <www.sciencedaily.com/releases/2011/04/110414131702.htm>.
University of Wisconsin-Madison. (2011, May 6). Precipitation, predators may be key in ecological regulation of infectious disease. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2011/04/110414131702.htm
University of Wisconsin-Madison. "Precipitation, predators may be key in ecological regulation of infectious disease." ScienceDaily. www.sciencedaily.com/releases/2011/04/110414131702.htm (accessed August 23, 2014).

Share This




More Plants & Animals News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Endangered Red Wolves Face Uncertain Future

Endangered Red Wolves Face Uncertain Future

AP (Aug. 22, 2014) A federal judge temporarily banned coyote hunting to save endangered red wolves, but local hunters say that the wolf preservation program does more harm than good. Meanwhile federal officials are reviewing its wolf program in North Carolina. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Farm Resurgence Grows With Younger Crowd

Farm Resurgence Grows With Younger Crowd

AP (Aug. 22, 2014) New England farms are seeing a surge in younger farm hands as the 'buy local' food movement grows across the country. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) According to a new study, spiders that live in cities are bigger, fatter and multiply faster. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins