At a glance
Tick surveillance and pathogen surveillance data sets used to develop tick surveillance data dashboards.
Blacklegged tick (Ixodes scapularis) and western blacklegged tick (Ixodes pacificus) by county in the contiguous United States
- Counties classified as "established" are those where six or more ticks of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period.
- Counties classified as "reported" are those where less than six ticks of a single life stage were collected in the county within a 12-month period.
- Counties classified as "no records" should not be interpreted as the tick being absent. No records could be a result of a lack of sampling efforts, tick collections, or a lack of reporting or publishing the results of sampling efforts.
- County status is cumulative. Once a tick species is recorded as "established" within a county, the status will remain "established" in subsequent years.
Established and reported records of I. pacificus and I. scapularis through Dec. 31, 2025
Tickborne pathogens identified in host-seeking blacklegged and western blacklegged (Ixodes species) ticks: status by county in the United States
- 2023 Update: Pathogens included in dataset:
- Borrelia burgdorferi sensu stricto
- Borrelia mayonii
- Borrelia miyamotoi
- Anaplasma phagocytophilum human active variant
- Ehrlichia muris eauclairensis
- Babesia microti
- Powassan virus
- Counties classified as "present" are those where indicated tickborne pathogens have been identified in one or more host-seeking Ixodes scapularis or Ixodes pacificus ticks, using pathogen species-specific molecular methods.
- Counties classified as "no records" should not be interpreted as the pathogen being absent. No records could be a result of a lack of sampling efforts, tick collections, pathogen testing in collected ticks, or a lack of reporting or publishing the results of sampling efforts.
- County status for tickborne pathogens is cumulative. Once a pathogen has been identified in host-seeking ticks within a county and recorded as "present", the status will remain "present" in subsequent years.