Is Dilution the Solution?

[Staff]

Is Dilution the Solution?
Scientists study how biodiversity affects the spread of animal-borne disease.
By Lynne Peeples, posted June 4th, 2009.

Scienceline Is Dilution the Solution?
excerpt from above:

Several studies published over the last few months have bolstered the case for the dilution effect in both West Nile and Lyme diseases. Washington University’s Allan looked at birds and mosquitoes along a gradient of rural-to-urban sites in the St. Louis area. As he moved from habitats with few humans to those with higher densities he found a simultaneous drop in biodiversity and rise in West Nile prevalence. “As diversity goes up, disease goes down,” says Allan, whose study was published in January 2009 in the journal Oecologica.

His findings align with work by John Swaddle, a biologist at the College of William and Mary in Virginia, published just a few months earlier in the journal PLoS ONE. Rather than counting species over tracts of land, Swaddle used public bird counts and health department reports to compare bird diversity between pairs of adjacent counties with and without human cases of West Nile. This way, he was able to factor out other potential explanations, such as differences in weather. Again, less biodiversity meant more disease.