Scientists identify 21 bird species that could spread Lyme disease 

Posted: 10th March 2021

Researchers using a machine learning programme have identified 21 bird species that could play a role in transmitting the Lyme disease bacterium (Borrelia burgdorferi) to ticks. The insights could help scientists predict where tick-borne diseases may appear. In response, medical professionals can better prepare for a Lyme disease diagnosis and treatment, improving treatments and outcomes.

Migratory birds are recognised as a potential vector for transporting the bacteria that causes Lyme disease but have been little studied. Ticks feeding on the birds can carry the bacteria, which can be transferred to humans, causing Lyme disease infection. 

“We know birds can infect ticks with the Lyme bacterium; however, until now, no one has systematically studied the ecological and evolutionary drivers that influence which bird species are most likely to host and spread Borrelia burgdorferi on a global scale,” said Daniel Becker, a Postdoctoral Fellow at Indiana University and lead author of the paper. “We set out to fill this gap by identifying traits of bird species that are most likely to pass Lyme to feeding ticks.”

In the study, published in the journal Global Ecology and Biogeography, researchers reviewed 102 studies containing data on 183 bird species. Of those, 91 carried ticks that tested positive for Borrelia burgdorferi, the bacteria that causes Lyme disease.

The researchers used a machine learning programme to compare these species’ traits with 4,691 other bird types. The model looked at various data points, including diet body composition, migration distance and global dispersal, as well as baseline corticosterone. This stress hormone can influence susceptibility to infection.

The programme identified 21 bird species that the scientists believe play a role in spreading Borrelia burgdorferi. The authors believe these species should be a priority for ongoing surveillance. Specifically, the model identified thrushes as the riskiest birds for transmission. 

Senior author Barbara Han, a disease ecologist at Cary Institute of Ecosystem Studies, explains why such data points were necessary, “To predict and monitor species that could spread tick-borne diseases to people, we first need to know which traits make certain animals good pathogen hosts. Here, we used machine learning to assess bird species traits, paired with Lyme infection data from ticks found on birds, to predict bird species that have the potential to spread Lyme.”

Beckers says the research provides compelling new evidence on the importance of birds as a vector for Lyme disease. “A tick could drop off a bird and into a garden or yard, where it could later bite and infect a person. If local medical practitioners are unfamiliar with Lyme symptoms, proper diagnosis could be delayed. Identifying where ticks are spreading could improve medical response to Lyme and other tick-borne diseases.”

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You can read the full paper, The macroecology and evolution of avian competence for Borrelia burgdorferi, here.