GREAT FALLS — Two Montana counties are now reporting confirmed sightings of the black-legged tick, best known for carrying Lyme disease.

The tick has now been identified in Sheridan County in northeastern Montana, which includes the community of Plentywood. This comes in addition to confirmation of the tick earlier this spring in Dawson County.

In the Dawson County instance, the unusual tick was found on a dog following a hunting trip.

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As for Sheridan County, the tick was detected by crews who were conducting active tick surveillance near a lake.

Up until now, ticks in Montana were not known to carry Lyme disease, but public health officials worry that could soon change.

Devon Cozart, an epidemiologist with the Montana Department of Public Health & Human Service (DPHHS), said, "We can have a situation where these are what I call just one-off ticks, meaning they maybe were flown in on a bird from another state, landed, and couldn't survive here long term, or we could have a population of ticks actively reproducing and currently present that would then introduce that greater risk," Cozart said.

Currently, there is no known increased risk in Montana for Lyme disease, or other pathogens transmitted by blacklegged ticks. However, the risk of encountering a blacklegged tick may be higher in Dawson and Sheridan counties.

Cozart says current research indicates ticks must be attached to a person for at least 24 hours before they can transmit Lyme disease, which makes it all that more important to check yourself for ticks if you've been outdoors.

The tick species most common in Montana at this time include the Rocky Mountain wood tick and the American dog tick. These ticks can spread diseases such as tularemia, Rocky Mountain spotted fever, and Colorado tick fever.

FROM THE MONTANA DEPARTMENT OF PUBLIC HEALTH & HUMAN SERVICES:

Department of Public Health and Human Services (DPPHS) officials are alerting the public about the recent identification of a tick new to Montana known as Ixodes scapularis, commonly referred to as a “deer tick” or “blacklegged tick”.

State health officials report that over the past year three blacklegged ticks were identified in the state for the first time through active surveillance conducted by researchers and public health officials. The ticks were found in Dawson and Sheridan counties.

Blacklegged ticks are much smaller and darker in color than most other ticks in Montana that might feed on humans. The presence of blacklegged ticks in Montana may increase the risk of exposure to new tickborne illnesses in the state.

“Not all types of ticks carry all tickborne illnesses,” said Devon Cozart, DPHHS Vectorborne Disease Epidemiologist. “The presence of this new type of tick in the state could mean that Montanans have an increased risk of exposure to diseases that weren’t previously a threat in Montana.”

Blacklegged ticks are extremely common in Northeastern United States. Recently, these ticks have steadily expanded into other states.

Lyme disease, anaplasmosis, ehrlichiosis, Powassan virus, hard tick relapsing fever, and babesiosis are examples of diseases known to be transmitted by the bite of a blacklegged tick.

One tick collected in Dawson County was confirmed to be a blacklegged tick by Rocky Mountain Laboratories in 2024. DPHHS, along with the Centers for Disease Control and Prevention (CDC), confirmed in the fall of 2024 that two ticks found in Sheridan County were blacklegged ticks. These two ticks were tested by CDC and no pathogens that can cause illness in humans were detected, including Lyme disease.

Currently, there is no known increased risk in Montana for Lyme disease, or other pathogens transmitted by blacklegged ticks. However, the risk of encountering a blacklegged tick may be higher in Dawson and Sheridan counties.

Public health officials are conducting further investigation to determine whether these ticks are found elsewhere in Montana and whether they are establishing their habitat in the state. DPHHS will continue to monitor tick activity in select locations throughout the state and will adjust guidance as needed if blacklegged ticks become established.

“Currently, tick experts do not think that the blacklegged tick is present throughout Montana,” Cozart said. “These ticks could have been carried into the state by a host animal, or they could be active and reproducing here – we just don’t know yet. We will be conducting further investigations this spring.”

The tick species most common in Montana at this time include the Rocky Mountain wood tick and the American dog tick. These ticks can spread diseases such as tularemia, Rocky Mountain spotted fever, and Colorado tick fever.

This spring, DPHHS is launching a citizen scientist program and is requesting the public’s help in tick surveillance, especially in Dawson and Sheridan counties. Anyone who thinks they have found a blacklegged tick is encouraged to fill out this online form. The form is also on the DPHHS website and includes instructions on how to submit the tick for identification.

Cozart states the best way to reduce your chance of developing an illness from a tick bite is to reduce your contact with ticks.

“Preventing tick bites is important while spending time outdoors, especially when walking through brushy or wooded areas,” she said. “Though tick activity slows during winter months, ticks can be active any time temperatures are above freezing. Any outdoor activity in any season that disturbs leaf brush (such as yardwork or hiking) or contact with other animals (such as hunting) increases the risk of encountering a tick.”   

To prevent tick bites, follow these tips:

• Wear an EPA registered insect repellent

• Treat clothing and gear with products containing 0.5% permethrin  

• Check for ticks often and carry a tick removal device such as tweezers 

• Shower soon after being outdoors  

• Put clothing in the dryer for 10 minutes after being outdoors to kill ticks 

• Check pets regularly for ticks and talk to a veterinarian about tick prevention products 

“If you find a tick, remove it safely and quickly,” Cozart added. “The less time a tick is attached, the less likely you are to develop an illness. If you have been bitten by a tick and start to feel sick with symptoms including fever, rash, body aches, and headaches, talk to your health care provider and let them know about your tick encounter.