Could Biodiversity Keep Humans Healthier?

With an increase in Lyme disease in the U.S. this spring, ecologists are searching for ways to control the spread of the disease. Recent evidence suggests that a higher biodiversity within ecosystems may in fact lower a human’s likelihood of contracting the disease, according to a recent NPR report.

A recent analysis published in the Proceedings of the National Academy of Sciences suggests that conserving wildlife and protecting wildlife habitat could also help humans avoid contracting Lyme disease and the West Nile virus. The idea is a highly debated hypothesis within the world of ecology called the “dilution effect.”

Many pathogens spend a portion of their lifetime within another animal such as a mouse or a crow. A deer tick or mosquito then transfers the pathogen from this animal to a human. The dilution effect suggests that increasing biodiversity will offer control of these diseases naturally.

Photo: Natural Habitat Adventures. Cautious yet confident, this Grey Wolf checks out the camera

Since pathogens are particular and don’t choose just any animal to live in, there will be more species for them to choose from. With more species around, a disease would be diluted among the various species within the ecosystem. As a result, a tick or a mosquito would be less likely to feed on an infected animal, and then less likely to pass that infection on to a human.

In researching deer mice in Utah, ecologist David Civitello and his team found a correlation between an increase in biodiversity and a decrease in infection. While not all diseases followed this pattern, Civitello saw the dilution effect occurring commonly.

Photo: Patrick J. Endres taken on Natural Habitat Adventures’ Natural Jewels of Costa Rica trip

Other ecologists think the dilution effect occurs more rarely than Civitello’s study suggested. Opposing ecologists think further studies are needed to prove the hypothesis. Civitello knows the hypothesis is not a solution to all of disease control but does find some benefit from it, explaining, “If there is some overlap in the benefits of biodiversity conservation and disease control, it can’t hurt.”