Birds may be a larger factor in the spread of Lyme disease in California than previously believed.
A recent study revealed birds are significant reservoirs of the bacterium Borrelia burgdorferi, which is responsible for Lyme disease, the University of California, Berkeley reported. Lyme disease is primarily spread to humans through bites from infected ticks.
"The role of birds in the maintenance of Lyme disease bacteria in California is poorly understood," said study lead author Erica Newman, a UC Berkeley Ph.D. student in the Energy and Resources Group and the Department of Environmental Science, Policy and Management. "This is the most extensive study of the role of birds in Lyme disease ecology in the western United States, and the first to consider the diversity of bird species, their behaviors and their habitats in identifying which birds are truly the most important as carriers."
Some of the Lyme-carrying birds identified in the study included American robins, dark-eyed juncos and golden-crowned sparrows, which exist in high concentrations in suburban areas.
"Birds are much more capable of carrying diseases long distances than the small-mammal hosts typical of Lyme disease, and so may constitute an underappreciated component of Lyme disease ecology," said Morgan Tingley, an ornithologist who was not part of this UC Berkeley-led study. "Particularly as we look to the future, birds may end up playing a larger role in disease ecology than other animals because of their ability to quickly and easily move long distances and to new habitats. In the same way that airplanes can help spread disease across nations, birds do the same thing for our ecosystems."
To make their findings, the researchers looked at bird and tick samples taken from four sites within the UC Hopland Research and Extension Center in northwestern California. Lyme disease spirochetes were found in 57 of the 100 birds that carried ticks.
"Another species of Lyme disease spirochete closely related to, but distinct from, Borrelia burgdorferi was detected in birds for the first time anywhere in the world," said study co-author Robert Lane, a medical entomologist and UC Berkeley Professor of the Graduate School, and a leading expert on ticks and Lyme disease.
The findings were published in a recent edition of the journal PLOS One.
