Tick species established in Montana, CDC-reported disease cases by county, and the county-level breakdown of where ticks and pathogens concentrate.
No tick species established in Montana yet — surveillance ongoing.
| Disease | Total cases | Counties | Years covered |
|---|---|---|---|
| Lyme disease Lyme disease is a bacterial infection (Borrelia burgdorferi) spread by black-legged ticks and the most common tick-borne illness in the US. | 132 | 56 | 23 |
| Spotted fever rickettsiosis Spotted fever rickettsiosis is a group of bacterial infections — Rocky Mountain spotted fever among them — spread by dog and wood ticks across the US. | 25 | 56 | 2 |
| Tularemia Tularemia is a highly infectious bacterial disease (Francisella tularensis) transmitted by tick bites, deer fly bites, and contact with infected animals. | 18 | 56 | 2 |
| Anaplasmosis Anaplasmosis is a bacterial infection (Anaplasma phagocytophilum) spread by black-legged ticks across the Northeast, Upper Midwest, and Pacific Coast. | 5 | 56 | 2 |
| Ehrlichia chaffeensis ehrlichiosis Ehrlichia chaffeensis ehrlichiosis is a bacterial infection of white blood cells spread by lone star ticks across the Southeast and south-central US. | 1 | 56 | 2 |
| Babesiosis Babesiosis is a malaria-like parasitic infection of red blood cells (Babesia microti) carried by black-legged ticks in the Northeast and Upper Midwest. | 0 | 56 | 2 |
| Ehrlichia ewingii ehrlichiosis Ehrlichia ewingii ehrlichiosis is a bacterial infection spread by lone star ticks, typically affecting immunocompromised patients in the southeastern US. | 0 | 56 | 2 |
| Undetermined ehrlichiosis/anaplasmosis Undetermined ehrlichiosis/anaplasmosis is the CDC reporting category for cases where the specific Ehrlichia or Anaplasma species could not be identified. | 0 | 56 | 2 |
No CDC-reported cases yet for any county in Montana.