BERKELEY (KCBS) — In a study released Wednesday, UC Berkeley researchers say that the role of birds in the spread of Lyme disease within California is more important than previously known.

While wood rats, western gray squirrels and other small mammals have been identified in previous studies as hosts for Borrelia burgdorferi, the bacterium responsible for Lyme disease, researchers found more than half of the common robins, juncos, and sparrows that were carrying ticks, were also carriers.

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Given the greater mobility of birds, the researchers think they may play a bigger role in spreading the disease.

“The role of birds in the maintenance of Lyme disease bacteria in California is poorly understood,” Erica Newman, one the lead authors of the study, said.

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Humans bitten by the ticks can get the disease, which can lead to a months or years of conditions ranging from joint pain to brain aliments.

The black-legged deer tick transmits the bacteria in the eastern and north-central regions of the United States, while the western black-legged tick spreads it in the West.

Researchers took blood samples from 623 birds representing 53 species. Fifty-seven of the 100 birds that carried the ticks with the Lyme disease bacterium were infected.

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Study co-author Robert Lane, a medical entomologist and a UC Berkeley professor also said that, surprisingly, “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.”