Loss of species large and small threatens human health

December 01, 2010

The loss of biodiversity--from beneficial bacteria to charismatic mammals--threatens human health. That's the conclusion of a study published this week in the journal Nature by scientists who study biodiversity and infectious diseases.

The work reveals a critical connection between conservation and disease. Species losses in ecosystems such as forests and fields result in increases in pathogens--disease-causing organisms--the researchers found.

The animals, plants, and microbes most likely to disappear as biodiversity is lost are often those that buffer infectious disease transmission. Those that remain tend to be species that magnify the transmission of infectious diseases like West Nile virus, Lyme disease, and hantavirus.

"We knew of specific cases in which declines in biodiversity increase the incidence of disease," says Felicia Keesing, an ecologist at Bard College in Annandale, N.Y., and first author of the paper. "But we've learned that the pattern is much more general: biodiversity loss tends to increase pathogen transmission across a wide range of infectious disease systems."

The pattern holds true for various types of pathogens--viruses, bacteria, fungi--and for many types of hosts, whether humans, other animals, or plants.

"When a clinical trial of a drug shows that it works," says Keesing, "the trial is halted so the drug can be made available. In a similar way, the protective effect of biodiversity is clear enough that we need to implement policies to preserve it now."

In the case of Lyme disease, says co-author Richard Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, N.Y., "strongly buffering species like the opossum are lost when forests are fragmented, but white-footed mice thrive. The mice increase numbers of both the blacklegged tick vector and the pathogen that causes Lyme disease."

Scientists don't yet know, Ostfeld says, why the most resilient species--"the last ones standing when biodiversity is lost"--are the ones that also amplify pathogens. Preserving natural habitats, the authors argue, is the best way to prevent this effect.

Global biodiversity has declined at an unprecedented pace since the 1950s. Current extinction rates are estimated at 100 to 1,000 times higher than in past epochs, and are projected to increase at least a thousand times more in the next 50 years. Expanding human populations can increase contact with novel pathogens through activities such as land-clearing for agriculture and hunting for wildlife.

Identifying the variables involved in infectious disease emergence is difficult but critical, says co-author Andrew Dobson of Princeton University.

Biodiversity is an important factor, but so are land use changes and human population growth and behavior, he says. "When biological diversity declines and contact with humans increases, you have a perfect recipe for infectious disease outbreaks."

The authors call for careful monitoring of areas in which large numbers of domesticated animals are raised or fish are farmed. "That would reduce the likelihood of an infectious disease jumping from wildlife to livestock, then to humans," says Keesing.

For humans and other species to remain healthy, it will take more than a village--we need an entire planet, the scientists say, one with its diversity thriving.
-end-
Much of the research described in the paper was funded by the National Science Foundation (NSF)-National Institutes of Health (NIH) Ecology of Infectious Disease (EID) Program and by the US Environmental Protection Agency.

Other co-authors are: Samuel Myers of Harvard Medical School; Charles Mitchell of the University of North Carolina at Chapel Hill; Kate Jones of the Zoological Society of London; Anna Jolles of Oregon State University; Peter Hudson of Penn State University; Robert Holt of the University of Florida at Gainesville; Drew Harvell of Cornell University; Peter Daszak and Tiffany Bogich of EcoHealth Alliance (formerly Wildlife Trust) in New York City; and Lisa Belden of Virginia Tech.

For more information, contact Lori Quillen (845-677-7600 x233; quillenl@caryinstitute.org) or Mark Primoff (845-758-7412; primoff@bard.edu).The Cary Institute of Ecosystem Studies is a private, not-for-profit environmental research and education organization in Millbrook, N.Y. For more than twenty-five years, Cary Institute scientists have been investigating the complex interactions that govern the natural world. Their objective findings lead to more effective policy decisions and increased environmental literacy. Focal areas include air and water pollution, climate change, invasive species, and the ecological dimensions of infectious disease.

Bard is a highly selective, independent four-year residential college of the liberal arts and sciences, located 90 miles north of New York City, in the historic Hudson Valley. Bard offers the bachelor of arts degree with concentrations in more than 40 academic programs, as well as graduate degrees in the arts, environmental studies, and education.

Cary Institute of Ecosystem Studies

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.