Information on Ticks in Vermont

What does the graph tell me?

1. Tick-related emergency room visits are most common in the spring, when blacklegged tick nymphs are abundant, and fall, when adult female blacklegged ticks look for one more meal before winter arrives. Few ticks are out searching for meals in December, January and February, so tick-related emergency department visits are low during those times.  
2. Spring tick activity is associated with increased cases of Lyme disease and anaplasmosis, and Vermonters continue to be at risk for anaplasmosis during the fall months.

How was this graph built?

The Health Department collaborates with hospitals across the state to collect data on recent emergency room (and some urgent care) visits. Information like the date of the visit, reason for the visit, and diagnosis are analyzed to detect public health events and monitor trends in disease activity.

What do all the bars and lines mean?

The graph shows the weekly percentage of emergency department visits for tick-related issues. The purple line represents the average percentage of visits due to tick-related issues at that time of year (based on 2004-2020 data). The green dotted line represents the highest percentage of tick-related visits that has been recorded at that time of year. The blue bars show the percentage of visits due to tick-related issues in the current year.

What Should I Do?

Protect, Check, Remove and Watch. Visit our Prevent Tick Bites & Tickborne Diseases webpage to learn how to prevent and respond to tick bites.

Name: Blacklegged tick (Ixodes scapularis)

Distribution: throughout Vermont

Habitat: wooded areas and fields with tall grass and brush

Hosts: white-footed mouse, deer mouse, chipmunks, shrews, white-tailed deer

Transmits: the pathogens that cause Lyme disease, anaplasmosis, babesiosis, Powassan virus disease, and Borrelia miyamotoi disease

Active: In Vermont, blacklegged tick peak activity typically occurs in May and June when nymphal ticks are looking for a host. Tick activity increases again in October and November when adult female ticks are looking for another host before winter. Although blacklegged tick activity typically follows this pattern, these ticks may be encountered any time of year when temperatures are above freezing.

How common are disease-carrying blacklegged ticks in Vermont?

The Vermont Department of Health initiated a project in collaboration with the Vermont Agency of Agriculture to understand the prevalence and geographic distribution of disease-carrying blacklegged ticks. Over 2,000 ticks were collected from 48 sites around the state in 2018; human-feeding nymphs and adult female ticks were tested for five pathogens.

PAthogen	Percentage of ticks that tested positive
Borrelia burgdorferi	53%
Anaplasma phagocytophilum	6%
Babesia microti	4%
Borrelia miyamotoi	2%
Powassan virus	0%

Blacklegged ticks can carry more than one pathogen at the same time. The most common combinations were the pathogens that cause Lyme disease and anaplasmosis (5%) and the pathogens that cause Lyme disease and babesiosis (3%).

Name: American dog tick (Dermacentor variabilis)

Distribution: throughout Vermont

Habitat: mostly in grassy fields and other areas with little tree cover

Hosts: small rodents and medium-sized wild mammals, domestic cats, dogs and humans

Transmits: the bacteria that causes tularemia (human cases in Vermont are extremely rare)

Active: April through September

Name: Brown dog tick (Rhipicephalus sanguineus)

Distribution: throughout Vermont

Habitat: wherever humans and dogs live including indoors, unlike other tick species

Hosts: mostly dogs

Transmits: the bacteria that causes Rocky Mountain spotted fever (no evidence of transmission in Vermont)

Active: throughout the year

Name: Lone star tick (Ambylomma americanum)

Distribution: single life stage found three Vermont counties, but is not considered established – able to complete its entire life cycle – in Vermont

The Health Department works with other state agencies to search for the lone star tick in Vermont and support people with information to protect themselves.

Habitat: woodlands with plenty of undergrowth and areas with tall, shaded grass

Hosts: squirrels, raccoons, deer, cattle, some bird species, cats, dogs and humans

Transmits: the pathogens that cause ehrlichiosis and tularemia (human cases in Vermont are extremely rare)

Active: April through September. While most ticks wait in grass or brush to grab on to people or animals who pass by (questing), lone star ticks also actively track down a host by following the trail of air the host breathes out.

Name: Squirrel tick (Ixodes marxi)

Distribution: throughout Vermont

Habitat: the nests of their hosts

Hosts: mostly squirrels, but also other medium-sized mammals; rarely bite humans

Transmits: Powassan virus (extremely rare in Vermont)

Active: generally, in warmer months

Name: Woodchuck tick (Ixodes cookei)

Distribution: throughout Vermont

Habitat: the burrow of their host animal; rarely on vegetation

Hosts: woodchucks, foxes, skunks, weasels, porcupines, small mammals, some bird species, raccoons, cats, dogs; rarely bite humans

Transmits: Powassan virus (extremely rare in Vermont)

Active: generally, in the summer months