Tick Surveillance

Ixodes tick surveillance
Non-Ixodes hard tick surveillance

Ixodes scapularis

Surveillance for Ixodes scapularis and pathogens found in this tick species in the United States pdf icon[PDF – 34 pages] Print only

Ixodes scapularis—Estimated and established distribution, 2019

Estimated distribution (yellow) of the blacklegged tick (Ixodes scapularis). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period.

Estimated distribution of areas where the blacklegged tick (Ixodes scapularis) could survive and reproduce (yellow), and counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within any 12-month period.

Ixodes scapularis lifecycle

Ixodes scapularis typically lays eggs in the spring. These hatch into larva in summer. The following spring, nymphs feed and then molt into adults later in the fall. Adults females will seek a blood meal and lay eggs the following spring, completing the lifecycle.

The lifecycle of Ixodes scapularis ticks generally lasts two years. During this time, they go through four life stages: egg, larva, nymph, and adult. After the eggs hatch, the ticks must have a blood meal at every stage to survive. Blacklegged ticks can feed from mammals, birds, reptiles, and amphibians. The ticks need a new host at each stage of their life.

Ixodes pacificus

Surveillance for Ixodes pacificus and pathogens found in this tick species in the United States. pdf icon[PDF – 27 pages] Print only

Ixodes pacificus—Estimated and established distribution, 2019

Estimated distribution (yellow) of the Western blacklegged tick (Ixodes pacificus). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period

Estimated distribution of areas where the Western blacklegged tick (Ixodes pacificus) could survive and reproduce (yellow), and counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. pacificus of a single life stage or more than one life stage of the tick were collected in the county within any 12-month period.

Ixodes pacificus lifecycle

Ixodes pacificus typically lays eggs in the spring. These hatch into larva in the following spring. During the summer, larvae feed and then molt into nymphs the following spring. During the summer, nymphs feed and then molt into adults over the winter. Adults females will seek a winter or spring blood meal before laying eggs in spring, completing the lifecycle.

The lifecycle of Ixodes pacificus ticks generally lasts three years. During this time, they go through four life stages: egg, larva, nymph, and adult. After the eggs hatch, the ticks must have a blood meal at every stage to survive. Blacklegged ticks can feed from mammals, birds, reptiles, and amphibians. The ticks need a new host at each stage of their life.

Guide to the Surveillance of Metastriate Ticks (Acari: Ixodidae) and their Pathogens in the United States pdf icon[PDF – 54 pages] Print only

Public Use Dataset

Status for Ixodes scapularis and 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 arise either from a lack of sampling efforts, lack of tick collection during sampling efforts, or lack of reporting or publishing the results of sampling efforts.

Established and reported records of I. pacificus and I. scapularis through Dec. 31, 2019 excel icon[XLS – 194 KB]––Right–click the link and select “save”.

Page last reviewed: May 27, 2020

Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD)