Tick-borne Diseases

Three Ticks


Tick-borne diseases are those spread by the bite of an infected tick. These diseases can be caused by bacteria, parasites, or viruses, although the diseases caused by bacteria are most common. Several tick species found in Connecticut can spread types of bacteria that can cause illness in humans, and infection with more than one is possible through one tick bite. Symptoms and treatment for each disease depends on the type of bacteria, parasite, or virus causing the illness. There are no vaccines to prevent these diseases. In Connecticut, surveillance is conducted to identify tick-borne diseases spread by ticks in the state and those that might be travel-related (diseases acquired out of the state). The Connecticut Department of Public Health conducts surveillance for the following tick-borne diseases: 



Borrelia miyamotoi disease


Lyme disease

Powassan virus disease

Rocky Mountain spotted fever (RMSF)



Ticks and Tick-borne Diseases of the United States


The most effective way to avoid getting sick from tick-borne diseases is to prevent tick bites.

Tick species and diseases they can spread in Connecticut include:


Blacklegged (“deer”) tick (Ixodes scapularis)

  • Anaplasmosis
  • Babesiosis
  • Borrelia miyamotoi disease
  • Lyme disease
  • Powassan virus disease (can also be spread by Ixodes cookei)

Lone Star Tick (Amblyomma americanum)

  • Ehrlichia chaffeensis
  • Tularemia

American Dog Tick (Dermacentor variabilis)

  • Rocky Mountain spotted fever
  • Tularemia

Connecticut Agricultural Experiment Station


The Connecticut Agricultural Experiment Station offers tick testing to Connecticut’s municipal and regional health departments for engorged ticks removed from people. Ticks are tested for the causative agents of anaplasmosis (Anaplasma phagocytophilum), babesiosis (Babesia microti), and Lyme disease (Borrelia burgdorferi). Not all ticks carry disease causing pathogens.


Tick Information

Information on Submitting Ticks

Summaries of Tick Testing

Tick Management Handbook


Additional Resources

Yale EIP logo


Tick-NET  Tick-Borne Diseases Network


Northeast Regional Center for Excellence in Vector-borne Diseases 


Connecticut Provider Reporting Resources


Reporting of Diseases, Emergency Illnesses, Health Conditions, and Laboratory Findings


Connecticut Provider Reporting Information


Connecticut Laboratory Reporting Information

Connecticut Annual Infectious Diseases Statistics


National Resources


Companion Animal Parasite Council: Reports of tick-borne diseases (Lyme disease, anaplasmosis, and Ehrlichiosis) in dogs


List of all tick-borne disease occurring in the United States


Tick bite data tracker


Workplace Safety - Tick-Borne Diseases - NIOSH


Vector Control Resources - CDC EHS




This page last updated 9/9/2022.