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Power to the pathogens: is habitat fragmentation good for bad bugs?

November 19, 2012

Power to the pathogens: is habitat fragmentation good for bad bugs?

Intact habitats are healthy places. Bats in contiguous tracts of Panamanian forest have fewer parasitic infections than their comrades on nearby islands

Intact habitats are healthy places. Bats in contiguous tracts of Panamanian forest have fewer parasitic infections than their comrades on nearby islands. Not only do the isolated night fliers have higher infection rates, they tend to get these infections from fewer parasites, especially Trypanosoma cruzi, a particularly nasty protozoan that causes Chagas disease in humans. While bats in intact ecosystems also carry trypanosomes, these are usually bat-specific strains that do not infect people.

One possible explanation is the Dilution Effect Theory, which Veronika Cottontail, a Ph.D. candidate from Germany's Ulm University, is testing at various locations in Panama – in the Panama Canal, which were isolated from the mainland a century ago, and the cloud forests of Western Panama. The theory says high host diversity curtails the prevalence of generalist parasites like T. cruzi. The dilution effect appears to apply to the bugs that cause Lyme disease and West Nile virus.

“Host diversity and trypanosome coverage is important to keep the generalist trypanosome at bay,” says Veronika during a recent research expedition on Barro Colorado Island. “Generalist trypanosomes are the ones capable of infecting more species and, among them, sometimes humans.”

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