Spread of Deer Ticks and Lyme Disease in Montana Raises Alarm for Doctors and Scientists

In the verdant highlands of Montana, biologist Grant Hokit embarks on a quest to locate ticks, specifically in a secluded meadow outside Condon. Armed with a homemade device constructed from interconnected plastic pipes and a large white flannel cloth, Hokit traverses a hiking trail dotted with long grasses and berry bushes.

He humorously refers to his makeshift instrument as “sophisticated,” but the mission is earnest: He’s sweeping the material over shrubs and vegetation, hoping to attract “questing” ticks that will latch onto the fabric. Ticks can be found dangling from grass blades along the path, awaiting a passing mammal or human host with their legs extended.

“We’ve got one!” Hokit announces triumphantly as a tick attaches itself to the flannel. After removal by hand, the specimen is placed in a vial for transport back to his laboratory in Helena for identification. Most of the ticks captured will likely be identified as Rocky Mountain wood ticks; however, Hokit is also on the lookout for new species invading the state.

Climate change driven by human activity has resulted in shorter winters, allowing ticks to spend more time active and thereby increasing their potential for hitchhiking on animals or people across different regions. In some instances, these migratory ticks carry diseases that can be transmitted to humans.

Hokit discovered deer ticks for the first time this year in northeastern Montana. These ticks are infamous for transmitting Lyme disease and other pathogens. The discovery is crucial for medical professionals like Dr. Neil Ku, an infectious disease specialist at Billings Clinic in eastern Montana, who often sees patients presenting symptoms associated with tick-borne illnesses long after they have been bitten.

“Fever, chills, feeling unwell—symptoms similar to many other infections we may encounter throughout the year,” explains Dr. Ku. It’s rare for patients to associate their symptoms with a tick bite and even more unusual for them to retain the offending tick for identification purposes. Determining whether someone may have contracted a tick-borne illness can be complex, as Dr. Ku points out.

Knowing the prevalence of different ticks in the region will help medical professionals better prepare for and diagnose tick-borne diseases, according to Devon Cozart, a zoonotic illness and vector-borne disease epidemiologist with the Montana Department of Public Health and Human Services. Cozart collects and tests ticks from field surveys across Montana to assess their pathogen load.

Whether a tick poses a risk to human health depends on its species as well as the mammal it feeds upon. For example, Rocky Mountain spotted fever can be transmitted by rodents that ticks have fed upon. Because the prevalence of particular diseases can vary among mammal populations, certain tick populations in one region may pose higher or lower risks to human health. This information is valuable for medical providers, notes Cozart.

Tick surveillance and testing aren’t universal across all states and counties. A 2023 survey of nearly 500 health departments found that approximately a quarter engage in some form of tick surveillance. Not all efforts are equally comprehensive, says Chelsea Gridley-Smith, director of environmental health at the National Association of City and County Health Officials.

Field surveys can be costly, making it challenging for numerous local and state health departments to conduct tick surveillance. In many cases, tick surveillance relies on a less expensive, more passive approach in which concerned patients, veterinarians, or doctors collect and send in ticks for identification.

“It does provide a little information about what ticks are actually interacting with people and animals, but it doesn’t delve into the details of how common ticks are in that area and how often they carry pathogens,” says Gridley-Smith. She notes that more health departments aim to initiate tick surveillance, but acquiring funding for these efforts can be difficult, particularly as federal public health grants from agencies like the Centers for Disease Control and Prevention dwindle.

Montana receives approximately $60,000 annually in federal grant funding, with the majority allocated towards mosquito surveillance due to its intensity and costliness. The remaining funds support field trips to search for ticks. Hokit notes that his small team lacks sufficient resources to survey all areas of Montana—a vast state—thus limiting their ability to closely monitor emerging populations of deer ticks.

He found these new deer ticks in two Montana counties, but he doesn’t have enough data to determine whether they have begun reproducing locally. To gather more information, Hokit utilizes data on climate and vegetation to predict potential habitats for deer ticks within the state. He is particularly interested in areas of western Montana such as the Flathead Valley. By focusing surveillance efforts in these regions, his team can inform the public about the arrival of deer ticks and the diseases they may carry.

As the climate warms, ticks are expanding their range to previously uninhabited areas of the country. However, local doctors and health officials may remain unaware of the arrival of new tick species and the associated health risks.