“Blacklegged tick” IDed in Eastern Montana
The Montana Department of Public Health and Human Services (DPPHS) recently announced the identification of Ixodes scapularis (the “deer tick” or “blacklegged tick”) within the state, in Eastern Montana (Dawson and Sheridan counties).
This is the first time a blacklegged tick has been identified in the state through active surveillance.
Blacklegged ticks are the primary vector responsible for transmitting diseases such as Lyme disease, Powassan virus disease, ehrlichiosis, babesiosis, anaplasmosis, and hard tick relapsing fever.
Blacklegged ticks are present throughout much of the Northeast U.S., though in recent years, blacklegged ticks have expanded west.
Despite the discovery of three blacklegged ticks in Eastern Montana, tickborne diseases such as Rocky Mountain spotted fever, Colorado tick fever, soft tick relapsing fever, and tularemia remain the most likely diseases to infect Montanans after a tick bite, because they are spread by the tick species that are most common and established in the state.
Clinician Recommendations
It is recommended to consider testing for the most common tickborne illnesses endemic to Montana for patients with a recent tick bite history in the state and generalized symptoms. Increased awareness of the potential for individuals with recent travel to Dawson and Sheridan Counties to be exposed to pathogens spread by blacklegged ticks is warranted. Current clinical guidance regarding diagnosis and management of tickborne illnesses have not changed. Antibiotic treatment is recommended for patients who present with compatible signs and symptoms and recent or likely exposure to a tick. Rocky Mountain spotted fever may progress to a deadly infection within as little as 7 days of symptom onset. Tickborne disease testing is recommended and available through the Montana Public Health Laboratory and/or commercial laboratories; however, providers should not delay initiating treatment pending testing results. Providers caring for a patient with suspected Lyme disease, anaplasmosis, babesiosis, or other illnesses spread by blacklegged ticks should assess the pretest probability of Lyme disease before testing. If Lyme disease infection is suspected or confirmed, travel history within 30 days should be obtained from the patient.
If you have a patient with lab-confirmed Lyme disease and no out-of-state travel history, please alert your local or tribal health department.
Click here to review the information sheet from the Montana Health Alert Network.