As surface temperatures rise and reshape ecosystems across the United States, a new study suggests that Lyme disease—one of the country's most common vector-borne illnesses—may not just spread but relocate.

University of Maryland researchers found that rising temperatures are likely to shift Lyme disease risk westward in Maryland, reducing transmission in some densely populated regions while increasing it in cooler, less-populated areas.

Published in the journal Royal Society Open Science on March 25, 2026, the researchers developed a detailed mechanistic mathematical model calibrated with two decades of ecological and case data to simulate how warming affects the lifecycle of the black-legged tick, Ixodes scapularis, the primary vector of the Lyme-causing bacterium Borrelia burgdorferi.

“Vector-borne diseases constitute about 16% of all infectious diseases of humans,” said the study’s senior author Abba Gumel, a Distinguished University Professor of Mathematics at UMD with a joint appointment in the University of Maryland Institute for Health Computing. Gumel also holds the Michael and Eugenia Brin Endowed Chair in Mathematics.

“This study helps answer a central question in ecology, whether and how anthropogenic climate change will alter these diseases’ distribution and burden,” he said.

A moving target

Scientists have long known that temperature plays a crucial role in tick development, survival and host-seeking activity. The new paper highlights a nuanced reality: ticks and Lyme disease transmission intensity peak within a narrow thermal band—17 to 20.5 degrees Celsius (roughly 63 to 69 degrees Fahrenheit). Outside that range, tick survival and transmission capacity decline.

As surface temperatures rise, that optimal “sweet spot” is expected to shift downward.

The researchers found that under moderate warming scenarios, parts of central Maryland, currently the hardest hit by Lyme, could see a decline in disease risk as temperatures rise above the range optimal for tick activity. Meanwhile, cooler western counties, including mountainous regions with historically few Lyme cases, may warm into the new optimal range, becoming more vulnerable to sustained transmission.

With more extreme warming, the shift becomes even more pronounced. 

“Under the high-emission scenario, Western Maryland falls fully within the new temperature window and emerges as the primary hot spot, while central, southern and eastern counties, where about 70% of the state’s population live, experience significant reductions in transmission due to thermal overshoot,” said study co-author Salihu Musa, a visiting assistant research scientist at UM-IHC. 

Importantly, the net effect of both warming scenarios is a statewide reduction in overall Lyme disease burden—but with the emergence of new risk areas in less populated western counties, the authors noted.

A patchwork future

The findings challenge a common assumption.

“Global warming does not uniformly intensify Lyme disease risk,” Gumel said. “Instead, it shifts the thermal landscape.” 

The resulting redistribution of risk creates a patchwork that could complicate public health planning, he said. But that planning is essential, as Lyme disease is unlikely to disappear on its own even without shifting weather patterns.

“Our theoretical analysis establishes that under current ecological and environmental conditions, Maryland will continue to experience Lyme disease outbreaks,” Gumel said. 

Rising temperatures only underscore the need for intervention. And no single intervention will do the trick, the authors said.

“A hybrid strategy combining rodent baiting, habitat clearance and personal protection offers the most robust pathway to elimination,” Musa said. “At moderate coverage levels—­­around 50%—this integrated approach remains effective under both moderate and high warming scenarios.”

He added that “elimination of Lyme disease in Maryland is mathematically feasible, but the threshold for intervention success rises with temperature.”

The study's authors emphasized that their mechanistic modeling framework intentionally focuses on temperature as the central climatic driver, enabling a clear, data-driven understanding of how rising temperatures reshape tick ecology and disease distribution. This approach provides public health officials with a powerful, interpretable tool for anticipating geographic shifts in risk and designing adaptive intervention strategies across Maryland.

Jessica Sadler received a 2026 Dean's Outstanding Employee Award from the University of Maryland’s College of Computer, Mathematical, and Natural Sciences. The winners of this award are recognized for their dedication to the well-being and operation of the college and its administrative units. The winner exemplifies strong capability, commitment and service to the college and the university community.

Sadler shared her experiences and insights as program manager for the Applied Mathematics & Statistics, and Scientific Computation (AMSC) graduate program.

This interview has been edited for length and clarity.

How and when did you end up at the University of Maryland?

I started my career as an English teacher. I taught English literature and English as a second language in Baltimore, Thailand and Japan. After completing a two-year contract at Tokyo International University, I returned to the U.S. in 2016 with the goal of transitioning into a more administrative and community-building role in academia. I wanted to support students behind the scenes in their academic journeys instead of in front of the classroom. I am grateful that my role in the AMSC Program allowed me to make this change. 

What is your favorite thing about working in your department?

There are so many things I love about working in the Department of Mathematics, but my favorite is working with our graduate students. They are creative, kind and altruistic. Whether it’s recruiting or onboarding new students, current students are always eager to volunteer their time and energy to help. I also enjoy working with the AMSC team: Director Radu Balan, Graduate Assistant Claudia Cerna and undergraduate employee Brent Li. Together, we’ve created a welcoming and productive environment in our Kirwan Hall 3rd-floor suite. 

Did you always think you’d work in academia?

Initially, I envisioned myself as a teacher, but not necessarily in academia. My perspective shifted when I served as a graduate assistant in the student affairs division at the University of Maryland, Baltimore County. That experience revealed my passion for supporting students outside the classroom and contributing to their academic success and well-being. 

What are your key responsibilities in your role?

My key responsibilities include managing the AMSC Program’s advising, admissions and recruitment processes, as well as assisting students with reaching degree milestones. I also plan and host events such as the Math Department’s annual Halloween Party. Additionally, I lead our department’s career and professional development programming, including a semesterly newsletter, The Calculated Career, to help students prepare for life after graduation.

What does your day-to-day look like in your job?

My day-to-day is a mix of multitasking and handling various responsibilities, often punctuated by student walk-ins. Academic offices operate in seasonal cycles. During the summer, I focus on onboarding new students and planning for the annual Math Department Orientation in August. The fall semester involves assisting with course registration, facilitating AMSC Graduate Committee meetings and preparing for admissions season. In the spring, the admissions committee reviews applications and we recruit new students. Throughout the year, I ensure that current students receive clear communication and support, and that they have a sense of community, so they can focus on their academics without being overwhelmed by administrative processes.

What do you like most about your job?

I enjoy the freedom to be creative. I have the opportunity to brainstorm and implement new ways to support students and foster community. For example, during COVID-19, I organized a Math Department mascot competition, inviting our community to nominate their pets as department mascots. This initiative brought a sense of fun and connection during a challenging time. Additionally, I launched a sticky note project in the women’s bathrooms in Kirwan Hall, where women can leave anonymous notes encouraging one another.

What did being selected for the CMNS Dean’s Staff award mean to you?

Being selected for the CMNS Dean’s Staff Award is an honor that means so much to me. It’s a recognition of the effort and dedication I’ve poured into my work. This award inspires me to continue striving for excellence and finding innovative ways to enhance the academic experience for everyone in the AMSC Program and the Department of Mathematics. I’m deeply grateful to be part of a community that values and celebrates the contributions of its members.

What motivates you to do your job well?

I am motivated by the belief that graduate students in my program and department deserve the best possible experience during their academic careers. By reducing administrative hurdles and offering consistent support, I want to ensure students’ time at UMD is as smooth and rewarding as possible so they can focus primarily on their academics and personal growth without being overwhelmed by the complexities of navigating a large university with its own zip code!

What is your favorite UMD memory?

Some of my favorite memories at UMD are the lunches with the AMSC team at nearby restaurants each semester. These gatherings allow us to connect and get to know one another outside of work. On sunny days, we sit outside on the patio at places like Looney’s. Seeing everyone’s smiling faces is always a highlight for me.

What do you like to do outside work?

I enjoy exploring my creative side through writing short stories, novels and screenplays, as well as drawing. Staying active is also important to me. I weightlift and jog at nearby parks nearly every day, especially when it’s warm. When I go out, I love attending live jazz performances and visiting art museums. 

The applied math specialty ranks at No. 15 and analysis ranks at No. 24, based on the most recent rankings by U.S. News & World Report.

The University of Maryland’s Department of Mathematics ranks No. 21 (7th among pubic institutions) in the 2027 Best Graduate Schools list released by U.S. News & World Report. Based on the most recent specialty rankings, applied math ranks at No. 15 and analysis ranks at No. 24. 

“I’m very pleased to see CMNS graduate programs continue to be recognized among the nation’s very best,” said Amitabh Varshney, dean of the College of Computer, Mathematical, and Natural Sciences (CMNS). “This recognition reflects the outstanding work and dedication of our department chairs, graduate program directors, faculty members and students who strive for excellence every day.”

The U.S. News rankings are based on reputational surveys and widely used by prospective students when considering where to apply.

“These latest graduate school rankings show the University of Maryland’s strength across a wide variety of scholarly domains and specialties, from the physical and social sciences to business and education,” said UMD President Darryll J. Pines. “We’re proud that our graduate programs are providing students with the vital knowledge and inspiration to address the most important challenges facing the world today.”