Tick Season is here
What does the graph tell me?
- There were very few tick-related emergency room visits across Vermont last week. This is likely because many of the nymphal ticks that were active earlier this year are inactive right now while they molt into adult ticks. These adult ticks will re-emerge in the autumn.
- Earlier this year during the spring and summer, emergency room and urgent care visits in Vermont for tick-related issues were consistently above average.
What should I do?
It is time to Protect, Check, Remove and Watch. Visit our Prevent Tick Bite and Tickborne Diseases webpage to learn how to prevent and respond to tick bites.
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. Interactions between ticks and humans can be monitored by searching the system for tick-related visits such as “tick in armpit” or “tick removal.”
What do all the bars and lines mean?
The graph shows the weekly percentage of visits due to tick-related issues. The blue line represents the average percent of visits due to tick-related issues at that time of year (based on information collected from 2004-2016). The orange line represents the highest percent of tick-related visits that has been recorded in that time of year. The green bars show the percent of visits due to tick-related issues in the current year. The information is analyzed on a weekly basis, and the most recent data for this year is pointed out in the green box.
Why do the bars and lines go up and down throughout the year?
Ticks are generally active when the weather is warm. Few ticks are out searching for meals in the December, January and February, so tick-related visits are low during those times. As spring approaches, ticks become more active and tick-related visits increase. In late summer (August and September) tick-related visits decrease mainly because ticks are less active while they molt from smaller nymphs into larger adult ticks. But tick-related visits increase once again when the adult ticks become active looking for one more meal before winter sets in.
Types of Ticks in Vermont
Thirteen different species of ticks have been identified in Vermont (click here for the full list). Of these 13 species, five are known to bite humans and four of those five can transmit diseases. However, over 99% of all tickborne diseases reported to the Vermont Department of Health are caused by only one tick: the blacklegged tick.
Name: Blacklegged tick (Ixodes scapularis)
Distribution: Blacklegged ticks can be found throughout Vermont.
Hosts: white-footed mouse, deer mouse, chipmunks, shrews, white-tailed deer.
Activity: in Vermont, blacklegged tick activity fluctuates throughout the year. After laying low during the cold winter months, these ticks usually become active in late March or early April. Their peak activity typically occurs in May and June when nymphal ticks are looking for a host. Tick activity increases once again in October and November when adult ticks are looking for another host before cold winter temperatures set in once again.
Although blacklegged tick activity typically follows this pattern, it is important to note that these ticks might be encountered at any time of year when the temperature is above freezing.
Name: American dog tick (Dermacentor variabilis)
Distribution: American dog ticks can be found throughout Vermont.
Habitat: found mostly in grassy fields and other areas with little tree cover
Hosts: feeds on small rodents and medium-sized wild mammals, domestic cats, dogs and humans
Active: from April through September
Name: Lone star tick (Ambylomma americanum)
Distribution: Lone star ticks are found primarily in southern Vermont.
Habitat: woodlands with plenty of undergrowth
Hosts: feeds on squirrels, raccoons, deer, cattle, some bird species, cats, dogs and humans
Transmits: The Lone star tick is responsible for transmitting ehrlichiosis in Vermont. Both nymphs and adults can transmit disease. Larvae cannot transmit disease.
Active: April through September
Name: Woodchuck tick (Ixodes cookei)
Distribution: Woodchuck ticks can be found throughout Vermont.
Habitat: generally found in the burrow of its host animal, rarely found on vegetation
Hosts: woodchucks, foxes, skunks, weasels, porcupines, small mammals, some bird species, raccoons, cats, dogs and humans
Transmits: Powassan virus disease, although this disease is extremely rare in Vermont
Active: generally in the summer months
Name: Brown dog tick (Rhipicephalus sanguineus)
Distribution: Brown dog ticks can be found throughout Vermont.
Transmits: The brown dog tick will bite humans, but there is no evidence that it transmits diseases in Vermont.
Hosts: mostly dogs
Habitat: Generally brown dog ticks can be found wherever humans and dogs live. Unlike other tick species, the brown dog tick is well-suited for living indoors.
Active: may be active throughout the year
Pathogen prevalence in blacklegged ticks
The Vermont Department of Health has collaborated with colleagues at the Vermont Agency of Agriculture and Lyndon State College to determine the prevalence of disease in Vermont's blacklegged tick population. Over 2,000 ticks were collected and tested between 2013 and 2016.
|PAthogen||Percentage of ticks that tested positive|
Over 60% of the ticks collected as part of this initiative tested positive for at least one disease. A small sample of these ticks was also tested for Powassan virus. Approximately 1% tested positive for Powassan virus.
Blacklegged ticks can carry more than one pathogen at the same time. Almost 5% of the ticks tested positive for two or more pathogens. The most commonly found combination (4.0%) found in ticks were the pathogens that cause anaplasmosis and Lyme disease.