Dr. Ostfeld's studies suggest that two seemingly unrelated topics — biodiversity and human disease — might be more closely intertwined than previously thought, at least in the case of Lyme disease. After trapping and counting animals that coexist with the white-footed mouse, his team reached the following conclusion: the greater the relative abundance of non-mouse hosts, the lower the percentage of Borrelia -infected ticks.
Ecologists have known for years that when forested landscapes are carved up, biodiversity decreases. In small forest fragments, the white-footed mouse population skyrockets, probably due to the loss of their predators and competitors. Meanwhile, the absence of diversity removes the natural checks on Borrelia transmission provided by other animal species. As a result, Dr. Ostfeld's group sees a dramatic rise in infected nymphs. 'The ticks have nothing but mice to feed on, but they have a lot of mice.
