Model predicts where Lyme disease-carrying ticks will develop

Researchers have developed a new approach to predicting where ticks that carry Lyme disease will arise. Photo by Jerzy Górecki/Pixabay
Researchers have developed a new approach to predicting where ticks that carry Lyme disease will arise. Photo by Jerzy Górecki/Pixabay

Dec. 22 (UPI) -- A new model helps identify areas with high populations of the ticks that carry Lyme disease, a study published Tuesday by the Proceedings of the Royal Society B found.

The information could allow public health officials to areas in which outbreaks of the disease, which can cause serious illness, will occur, the researchers said.


"Our research indicates that the geographic spread of black-legged ticks and Lyme disease is fairly predictable," study co-author Brian Allan told UPI.

"So it may be possible to accurately predict where Lyme disease will occur next and take public health measures to prevent transmission in these new areas," said Allan, an entomology professor at the University of Illinois Urbana-Champaign.

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Black-legged ticks carry the bacterium that causes Lyme disease, an infection that affects the nervous system, heart and joints, according to U.S. Centers for Disease Control and Prevention.

Each year, approximately 30,000 cases of Lyme disease are reported to county and state health departments across the country, although many more people likely have the disease and don't know it, the Centers for Disease Control and Prevention estimates.

The model developed by Allan and his colleagues uses this historical data and combines it with analyses of landscape features associated with the spread of ticks, the researchers said.

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Counties that get "invaded" with black-legged ticks tend to be adjacent to counties that have been invaded in the past, according to Allan.

In addition, in some Midwestern states, areas adjacent to major rivers experience significant increases in black-legged tick populations "in sequence," he and his colleagues said.

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For example, in Illinois, ticks "first arrived along the Illinois River and then spread up and down the river quite quickly," Allan said.

Levels of forest cover in a county can also predict the future occurrence of ticks where none had been previously reported, the researchers said.

To test their model, Allan and his colleagues, including Allison Gardner, a professor of biology and ecology at the University of Maine, used data gathered before 2012 to determine how ticks would spread into new areas in the Midwest between 2012 and 2016.

The model accurately predicted the appearance of ticks in new counties more than 90% of the time, they said.

The researchers identified 42 counties in the Midwest where black-legged ticks are likely to be detected by the end of 2021. The evidence suggests those ticks will carry the Lyme disease bacterium, according to the researchers.

"Some of the best measures for preventing Lyme disease are to educate the public where there is risk of exposure to ticks and encourage people to take preventative measures, such as tick checks and use of repellents," Allan said.

"We believe an improved understanding of not just where Lyme disease occurs already, but where it also could occur in the future, greatly helps with targeted public health messaging," he said.

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