The decline of large mammals – like elephants and giraffes – is problematic for a number of reasons. Their loss disturbs ecosystems, not to mention the moral implications of allowing some of the most majestic creatures on Earth to approach extinction. But new research suggests another reason we should worry about the loss of large wildlife.
Researchers from the University of California – Santa Barbara have found that a decrease in the number of large animals in an ecosystem is directly correlated with an increase in disease risk for humans. Losses of large animals – called defaunation – leads to rodentation, or an explosion in rodent populations
Rodents are hosts to fleas, tick, and mites, which frequently carry pathogens dangerous to humans. Take the case of fleas. In the Middle Ages, they spread the Black Plague. Today, they carry diseases like Bartonellosis, a group of bacterial pathogens that can cause memory loss and liver and spleen damage.
The study focused on an area of Kenya where rodent-borne diseases are already common. Using electric fences, researchers excluded large animals from designated plots of land. Rodent populations in those plots quickly doubled, and the flea population increased with them. Genetic testing of the fleas confirmed that they carried large numbers of disease pathogens.
Researchers believe the loss of wildlife in parts of Africa may be responsible for exacerbating public health issues in those areas. They also warn that the same phenomenon has been seen in other sites globally.
Their findings are just another reason that the protection of large wildlife is imperative, in Africa and throughout the world.
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Photo, taken April 1, 2005, courtesy of Tambako via Flickr.
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Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.