do ticks feed on birds

Birds play an underrecognized role in spreading tickborne disease. Their ability to travel great distances and propensity to divide their time between different parts of the world—patterns that are changing due to climate change—allow them to spread such diseases. Scientists can anticipate the potential locations of tickborne diseases that could become dangerous for humans by identifying the bird species that can carry pathogens that infect ticks.

The research team created a model that could identify birds known to spread Lyme to ticks with 80% accuracy, and it identified 21 species that should be prime candidates for surveillance.

“This research demonstrates the efficacy of machine learning in detecting pathogenic species,” remarks Sam Scheiner, a program director in the NSF’s Division of Environmental Biology. This strategy offers a valuable tool for stopping disease outbreaks and can be used for a variety of other animal-transmitted diseases, including COVID-19. “.

Finding potential bird species that may carry Lyme disease could have a direct impact on human health. Tickborne diseases, especially Lyme disease, can be difficult to diagnose. Medical professionals can better diagnose and treat patients by being aware of the areas where ticks and the diseases they carry are spreading.

A U.S. National Science Foundation-funded study published in the journal Global Ecology and Biogeography used machine learning to identify bird species with the potential to transmit the Lyme disease bacterium Borrelia burgdorferi as ticks feed on the birds.

Global synthesis reveals bird traits that promote Lyme and flags high-risk species

Because they can travel great distances and have a propensity to spend time in different parts of the world, birds play an underappreciated role in the spread of tickborne disease. These patterns are changing as a result of climate change. The identification of bird species capable of transferring pathogens to ticks aids scientists in forecasting potential tickborne disease hotspots and human health risks.

Machine learning was utilized in a recent study that was published in the journal Global Ecology and Biogeography to identify bird species that could potentially spread the Lyme disease bacteria (Borrelia burgdorferi) to feeding ticks. The team created a model that, with 80% accuracy, identified birds known to spread Lyme disease and flagged 2021–2022 new species that should be given priority for surveillance.

“We know birds can infect ticks with the Lyme bacterium, but 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,” says lead author Daniel Becker, a postdoctoral fellow at Indiana University. By determining the characteristics of bird species that are most likely to transmit Lyme to feeding ticks, we set out to close this gap. “.

Disease ecologist and senior author Barbara Han of the Cary Institute of Ecosystem Studies states, “We first need to know which traits make certain animals good pathogen hosts in order to predict and monitor species that could spread diseases carried by ticks to humans.” Here, we combined data on Lyme infection from ticks found on birds with machine learning to evaluate the characteristics of bird species in order to identify those that could potentially spread the disease. “.

For this investigation, the researchers looked through published literature to find studies that described ticks found feeding on birds having Lyme disease. 102 studies with data from ticks found on 183 bird species were found through the global search; 91 of these carried ticks that tested positive for Borrelia burgdorferi. Because these bird species are known to transmit Borrelia burgdorferi to feeding ticks, they are regarded as competent reservoir species. The species that have been flagged are widespread, occurring in the Americas, Africa, Asia, and Oceania.

Next, 4691 different bird species’ traits were compared to those of competent bird species using machine learning. Data comprised geographic information such as migration distance, global dispersal, and maximum elevation, as well as life history characteristics such as diet composition, foraging location, body size, lifespan, reproductive rate, and fledgling age. Additionally, they examined baseline corticosterone, which is a stress hormone in birds and can affect an infection’s susceptibility.

The model identified birds with 80% accuracy that were known to spread Lyme to ticks, and it also identified 2021 new species that should be prioritized for surveillance based on their sharing of traits with known competent species. In addition to being widely dispersed, high-risk species typically have low baseline corticosterone levels, breed and winter at high latitudes and low elevations, and fall on either extreme of the pace-of-life continuum (species that breed late and live longer, or breed early and die young).

Turdus species—also referred to as true thrushes—were found to have a noticeably higher probability of competence than other taxa. According to this research, thrushes may be the bird species most at risk of spreading Lyme disease. Passerines, or perching birds, as well as birds that feed mainly on seeds and those that forage on the ground (putting them in danger of being bitten by questing ticks) also tended to be more competent.

Finding bird species that are Lyme-competent may directly affect human health. Tickborne diseases, especially Lyme disease, can be difficult to diagnose. Medical professionals can better diagnose and treat patients by being aware of the areas where ticks and the diseases they carry are spreading.

Many birds are shifting their breeding ranges northward due to climate change. Ticks and infections move into higher latitudes along with birds. Certain bird species now live in cities and suburbs either full-time or occasionally. The risk that locals will get a tickborne disease is increased by birds that can thrive in urban settings, particularly those that are overwintering in these new locations near to people.

Birds don’t directly transmit Lyme to humans, but they can transport infected ticks to new areas where there hasn’t been a history of Lyme cases, according to Becker. A tick may fall from a bird and land in a yard or garden, where it may subsequently bite and infect a human. If local doctors are not familiar with Lyme disease symptoms, a proper diagnosis may not be made right away. Knowing the tick-transmission zones may help doctors treat Lyme and other tick-borne illnesses more effectively. “.

“These results remind us that pathogen competence varies tremendously, even among animals of the same family,” Han says in his conclusion. In addition to Lyme, machine learning techniques enable us to predict at-risk species globally by analyzing animal traits. These techniques can also be applied to other tickborne and zoonotic diseases that involve multiple host species. These forecasts may offer vital information to direct early treatments, stop the spread of disease, and safeguard our health. “.

Story Source:

Materials provided by Cary Institute of Ecosystem Studies. Original written by Antje Schultner. Note: Content may be edited for style and length.

Journal Reference:

• Becker, DJ, Han, BA. T. he macroecology and evolution of avian competence for Borrelia burgdorferi. Global Ecol Biogeogr, 2021 DOI: 10. 1101/2020. 04. 15. 040352 .

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