Reports of tickborne diseases are on the rise in the U.S. and Vermont. States in the Northeast, Mid-Atlantic and Upper Midwest have the highest incidence of Lyme disease in the country. While Lyme disease is the most common tickborne disease in Vermont, other diseases like anaplasmosis and babesiosis are becoming more common. 


Diagnosis and Treatment Best Practices for Tickborne Diseases

The blacklegged tick is responsible for spreading all five tickborne diseases in Vermont (in order of prevalence): Lyme disease, anaplasmosis, babesiosis, hard tick relapsing fever, and Powassan virus

Black legged tick
  • People are most likely to be infected April through August when the abundance of host-seeking tick nymphs is highest.  
  • Nymphs are very small (< 2mm) and difficult to see unless they become engorged with blood. Even when engorged, nymphs may evade timely detection and removal.  
  • Up to half of people diagnosed with Lyme disease don’t recall being bitten by a tick. 


Testing Considerations 

Consider testing symptomatic patients. 

Laboratory testing for tickborne diseases should be considered for patients presenting with non-specific influenza-like illness in the summer or fall, especially if there is a history of a tick bite or exposure to tick habitat. However, up to half of people diagnosed with Lyme disease don’t recall being bitten by a tick—likely due in part to tick nymphs very small size (<2mm) that makes detection and timely removal more difficult. 

Signs and symptoms of tickborne disease may include:  

  • Fever
  • Chills
  • Malaise
  • Headache  
  • Muscle and joint pains
  • Lymphadenopathy
  • Circular expanding rash (erythema migrans) found in 70% of Lyme disease cases.

Some patients with tickborne disease may also present with neurological, cardiovascular, hematologic or gastrointestinal symptoms.

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Testing ticks after removal is not recommended as a diagnostic tool 

Tick testing results should not be used as a proxy for tickborne disease testing in patients. Results can lead to unnecessary antibiotic treatment without conclusive evidence of patient infection. Instead, advise patients to return immediately for clinical evaluation if symptoms occur.

Using panels to test for multiple tickborne diseases is recommended since coinfections are possible.

Lyme Disease

Serologic testing is the principal means of laboratory diagnosis of Lyme disease. Current recommendations include using a sensitive enzyme immunoassay (EIA) or immunofluorescence assay, followed by a western immunoblot assay for specimens yielding positive or equivocal results. Some tests give results for two types of antibody, IgM and IgG. Positive IgM results should be disregarded if the patient has been ill for more than 30 days. In 2019, FDA cleared several Lyme disease serologic assays based on a modified two-test methodology using a second EIA in place of a western immunoblot assay. 

More on Lyme disease


Diagnosed by PCR (most sensitive during the first week of illness), or a 4-fold increase in IgG antibody titers (one obtained the first week of illness followed by a second 2–4 weeks later). IgM tests alone should not be used for diagnosis. 

More on anaplasmosis


Diagnosed by peripheral blood smear or PCR. An IgG antibody titer can be supportive evidence, but positive antibody tests do not differentiate between recent and past infection.

More on babesiosis

Hard tick relapsing fever

Diagnosed by PCR and antibody-based tests. Most patients acutely symptomatic with hard tick relapsing fever are seronegative, so PCR testing is preferred. 

More on hard tick relapsing fever

Powassan Virus

Diagnosed by finding virus-specific IgM antibodies in serum or cerebrospinal fluid (CSF). Powassan virus testing is not routinely available through clinical or commercial laboratories, but testing is available free of charge through the Health Department Laboratory if the patient:

  • Is hospitalized with meningitis or encephalitis
  • Has a presumed infectious cause of illness
  • Has negative or concurrent testing for more common causes of meningitis and encephalitis such as West Nile virus, Lyme disease, herpes and varicella.

Find more information and the instructions for ordering Powassan virus testing at the Department of Health Laboratory on the Powassan virus page

Use clinical judgment when ordering and interpreting antibody-based laboratory tests.

Antibodies can take several weeks to develop, so patients may initially test negative if infected recently. Pursue convalescent testing in these instances.

Antibodies normally stay in the blood for months or even years after the infection is gone; therefore, the test cannot be used to determine cure. Infection with other diseases, including tickborne or viral, bacterial, or autoimmune diseases, can result in false positive test results. 

Ask about travel history. 

While it is more likely for Vermonters to be exposed to a locally transmitted tickborne pathogen, travel to other areas of the United States may pose a risk for other tickborne diseases not found in Vermont.

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Reporting Tickborne Disease   

Health professionals in Vermont must report all cases of Lyme disease, anaplasmosis, babesiosis, hard tick relapsing fever, and Powassan virus to the Health Department.  

How to Report an Infectious Disease 

Treatment Recommendations 

Don’t wait to treat tickborne diseases. 

Tickborne diseases can be difficult to diagnose, particularly in the early stages of illness. Patients should be treated presumptively based on clinical suspicion (fever, rash, flu-like illness) while awaiting test results, and treatment should be completed even if antibody testing early in illness is negative. Doxycycline may be used as first-line treatment for suspected Lyme disease and anaplasmosis in patients of all ages. Long-term antibiotic use is not recommended and has been linked to serious, even deadly, complications. Find more treatment guidance for Lyme disease, anaplasmosis, and babesiosis

Consider use of tick bite prophylaxis to prevent Lyme disease. 

Lyme Disease Prophylaxia after tick bite
Click here to download

Most tick bites do not result in disease transmission, but antimicrobial post- exposure prophylaxis given within 72 hours after tick removal can be appropriate  after high-risk tick bites, defined as: 

  1. The tick bite occurred in Vermont or surrounding states 
  2. The tick can be identified as an adult or nymph blacklegged tick, and 
  3. The tick was engorged with blood, not flat.

Counseling Patients 

Navigating Difficult Conversations with Patients 

Lyme disease can be a controversial topic. Patients may be skeptical in consultations, have difficult questions, and recall misinformation. Listening and responding with compassion, curiosity, and validation is essential. Point them to good resources, walk through the reasoning, and come up with a decision together. A trusting relationship and collaboration are essential to understanding their history and creating a diagnostic and treatment plan. 

For instance, most cases of Lyme disease are cured with 2-4 weeks of antibiotics, but some people have symptoms lasting more than six months after treatment, a condition called Post-treatment Lyme Disease Syndrome (PTLDS). Some people call this “chronic Lyme disease,” but many experts avoid using this term because there is no clear clinical definition. 

It is not clear why this happens, but it does not appear to be caused by an ongoing infection with Borrelia burgdorferi. There’s a critical need to understand the causes of these long-lasting symptoms more thoroughly so health care providers can best treat them. When speaking with patients, remember how challenging and confusing this experience can be, and don’t reject patients’ experiences or symptoms. 

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Lyme FAQs

We recommend referring to this trusted and comprehensive source of Lyme FAQs (CDC) to help respond to patients’ questions and concerns.

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Counsel patients on how to prevent tickborne diseases by preventing tick bites. 

People who present with a tick bite are likely to encounter ticks again. Dog and outdoor cat owners are also more likely to encounter ticks and should take extra precautions.  

Prevent tick bites and tick bite illnesses by following these steps: 

  • Protect: Avoid areas where ticks live, cover up, use EPA-registered tick repellents, wear permethrin-treated clothing, and protect your pets. 
  • Check: Check for ticks after spending time in tick habitat. 
  • Remove: Remove attached ticks right away. 
  • Watch: Watch for symptoms for 30 days after a tick bite and tell your provider if you get sick. 

Get more information for patients from our prevention page, 

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New Design! Order Materials for your Patients  

The Health Department offers information and free professionally printed resources that providers can share with patients so they can take simple steps to prevent tickborne diseases. 

Order Now!

Training Modules and Free Continuing Education (CDC)

Below is a curated list of clinician training modules from CDC on tickborne diseases. They focus on the tickborne diseases relevant in Vermont, and provide the latest information on research, diagnosis, and treatments. Each training is free and provides free continuing education credits.

Lyme disease

Lyme Disease Updates and New Educational Tools for Clinicians
This one-hour webinar provides health care professionals and their patients with updated information on Lyme disease and new educational tools. Topics covered include populations at risk, early signs and symptoms, appropriate use of diagnostic tests, appropriate use of antibiotics, and clinician and patient education on early signs and symptoms, tick bite prevention and post-exposure prophylaxis.

Lyme Disease Training Modules
The four-part series helps health care providers to recognize, diagnose and treat Lyme disease. This resource is valuable for primary care clinicians, public health professionals, pharmacists, and health educators. Each module is one hour long.

  • Module 1: Introduction to Tickborne Diseases and Disease Prevention (WB4328) Topics covered include Lyme disease transmission and geographic distribution, care of a patient presenting with a tick bite, appropriate use of post-exposure prophylaxis, and patient education about tick bite prevention.
  • Module 2: Lyme Disease Clinical Overview (WB4329) Topics covered include early localized and disseminated manifestations, differentiating erythema migrans from other similar skin conditions, and recognizing clinical presentations that might suggest tickborne disease co-infections.
  • Module 3: Lyme Disease Testing and Diagnosis (WB4330) Topics covered include how to select validated tests, why there is currently no “test of cure,” how pretest probability and disease stage inform whether to test for Lyme disease, the significance of the seroconversion window period, and why testing for Lyme disease may not be clinically helpful for patients with erythema migrans.
  • Module 4: Lyme Disease Treatment and Management (WB4380) Topics covered include treatment options for erythema migrans, clinical management of Lyme carditis, Lyme arthritis and neurologic Lyme disease, and care of patients with persistent symptoms attributed to Lyme disease.
Ehrlichiosis and Anaplasmosis

Diagnosis and Treatment of Ehrlichiosis and Anaplasmosis is a one-hour interactive clinical education tool with case-based scenarios that provides technical training on the diagnosis and treatment of ehrlichiosis and anaplasmosis. Topics covered include geographic distribution of cases, clinical manifestations including abnormal laboratory indicators, recommended treatment, testing options, and prevention. 

Powassan virus disease

Viral Tickborne Disease Training (WB4496)

This one-hour interactive course provides information about tickborne viral diseases prevalent in the United States, including Powassan, which is found in Vermont, but rarely reported in humans. It covers geographic distribution, tick vectors, seasonality, clinical characteristics, diagnostic tools and limitations, and tick bite prevention.

Additional Reading
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2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease
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Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis – United States: A Practical Guide for Health Care and Public Health Professionals
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2020 Guideline on Diagnosis and Management of Babesiosis
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Suggested Reporting Language, Interpretation and Guidance Regarding Lyme Disease Serologic Test Results
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Lyme Disease Updates and New Educational Tools for Clinicians
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Lyme Disease Rashes and Look-alikes (CDC)
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