Does biodiversity protect humans against infectious disease?

Authors

  • Chelsea L. Wood,

    Corresponding author
    1. Department of Biology, Stanford University, Stanford, California 94305 USA
    2. Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309 USA
    Search for more papers by this author
  • Kevin D. Lafferty,

    1. U.S. Geological Survey, Western Ecological Research Center, c/o Marine Science Institute, University of California, Santa Barbara, California 93106 USA
    Search for more papers by this author
  • Giulio DeLeo,

    1. Department of Biology, Stanford University, Stanford, California 94305 USA
    2. Dipartimento di Scienze Ambientali, Università degli Studi di Parma, 43100 Parma, Italy
    Search for more papers by this author
  • Hillary S. Young,

    1. Marine Science Institute and Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106 USA
    2. Smithsonian Institution, Division of Mammals, Washington, D.C. 20013 USA
    Search for more papers by this author
  • Peter J. Hudson,

    1. Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, Pennsylvania 16802 USA
    Search for more papers by this author
  • Armand M. Kuris

    1. Marine Science Institute and Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106 USA
    Search for more papers by this author

  • Corresponding Editor: D. M. Tompkins.

Abstract

Control of human infectious disease has been promoted as a valuable ecosystem service arising from the conservation of biodiversity. There are two commonly discussed mechanisms by which biodiversity loss could increase rates of infectious disease in a landscape. First, loss of competitors or predators could facilitate an increase in the abundance of competent reservoir hosts. Second, biodiversity loss could disproportionately affect non-competent, or less competent reservoir hosts, which would otherwise interfere with pathogen transmission to human populations by, for example, wasting the bites of infected vectors. A negative association between biodiversity and disease risk, sometimes called the “dilution effect hypothesis,” has been supported for a few disease agents, suggests an exciting win–win outcome for the environment and society, and has become a pervasive topic in the disease ecology literature. Case studies have been assembled to argue that the dilution effect is general across disease agents. Less touted are examples in which elevated biodiversity does not affect or increases infectious disease risk for pathogens of public health concern. In order to assess the likely generality of the dilution effect, we review the association between biodiversity and public health across a broad variety of human disease agents. Overall, we hypothesize that conditions for the dilution effect are unlikely to be met for most important diseases of humans. Biodiversity probably has little net effect on most human infectious diseases but, when it does have an effect, observation and basic logic suggest that biodiversity will be more likely to increase than to decrease infectious disease risk.

Ancillary