Tick-related emergency room visits are most common in the spring and fall. This graph shows the weekly percentage of emergency department visits for tick-related issues, with the purple line showing the average percentage of visits (based on 2017-2024 data), the green line showing the highest percentage of visits recorded at that time, and the blue bars indicating the current year.


 

Tick Species Found in Vermont

Every year, ticks are collected from several locations around Vermont and identified by their species, life stage, and sex. Blacklegged ticks are responsible for 99% of all tick bite illnesses reported to the Vermont Department of Health. 

Blacklegged Tick Life Cycle

The blacklegged tick goes through four life stages: egg, larva, nymph, adult. This life cycle lasts about two years. At each stage (with the exception of egg), the tick must attach to a new host for food. Once attached, it will suck the blood of its host slowly, for several days. When the tick is full, it will fall off on its own. This may take as little as 3-6 days, but up to two weeks. It may leave behind a tiny red bump.

Illustrative chart displaying the life cycle between birth and 2+ years old for Ixodes scapularis, or the blacklegged tick. Adult ticks seek blood-meals in the fall, whereas nymphal ticks seek blood-meals in the spring.

This means that humans and other animals are most at risk for blacklegged tick bites: 

  • During late spring (May and June), when larvae become nymphs and need a new food source.
  • In the fall (October and November), when nymphs become adults and need a new host.

If a host animal has a tick bite illness already, such as Lyme disease, the blacklegged tick feeding off of it will then become infected for life. When that same tick later bites on a human, it will spread the disease.

Found a Tick?

Share information about where and what kind of ticks you find to the Vermont Tick Tracker.

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Tick Bite Illnesses Impacting Vermonters

Lyme disease is the most common tick bite illness in Vermont, followed by anaplasmosis and then babesiosis. Cases of anaplasmosis and babesiosis have increased significantly over the last ten years.

Cases of hard tick relapsing fever and Powassan virus are less common today; there have been fewer than 65 cases of hard tick relapsing fever reported to the Health Department since its emergence in 2016, and three cases of Powassan virus in Vermont residents since 1999.

Explore tick bite illness data

How common are disease carrying ticks in Vermont?

Several trends were revealed in the most recent Tick Pathogen Surveillance Report (2018-2022):

  • 94% of the ticks collected were blacklegged ticks.
  • Over half of all blacklegged ticks tested were infected with at least one pathogen; Borrelia burgdorferi (Lyme disease) was the most common.
  • Borrelia burgdorferi (bacterium that causes Lyme disease) was the most common pathogen infecting blacklegged ticks with an infection prevalence of 56.7% for adult ticks and 24% for nymph ticks.
  • Infection prevalence and density of infected ticks were highest in southwestern Vermont.
  • Addison County had the highest density of adult ticks (per 1,000m2).
  • Rutland County had the highest density of nymph ticks (per 1,000m2). This is significant because ticks in the nymph life stage are tiny (less than 2 mm) and difficult to see, and they may be able to feed on human hosts longer, increasing the likelihood of tick bite illness.

In a special study to evaluate other ticks in Vermont, 1,341 American dog ticks (Dermacentor variabilis) collected during 2018-2023 were tested at the CDC for Rickettsia rickettsii, the bacterium responsible for Rocky Mountain spotted fever; all were negative.

Four lone star ticks (Amblyomma americanum) collected during the same period were tested for Ehrlichia chaffeensis and Ehrlichia ewingii, bacteria responsible for ehrlichiosis in the eastern United States; all were negative.

Additional Reading
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2018-2022 Tick Pathogen Surveillance Report
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2021 Tick Pathogen Surveillance Report
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2020 Tick Pathogen Surveillance Report
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2019 Tick Pathogen Surveillance Report
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2018 Tick Pathogen Surveillance Report
Document or PDF
2017 Tick Pathogen Surveillance Report
Document or PDF
2016 Tickborne Disease Program Report
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2015 Tickborne Disease Program Report
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2014 Tickborne Disease Program Report
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