Blacklegged Ticks Identified In Eastern Montana
Department of Public Health and Human Services 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 the 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, 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.
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 For more information about ticks and tickborne diseases, please visit: About Ticks and Tickborne Disease | Ticks | CDC.
