On this page you will find information for healthcare providers about ticks of medical importance in Virginia, tickborne diseases that are reportable in Virginia, as well as diseases that may be emerging, but are not reportable.
Surveillance Case Definitions
Several tickborne diseases are reportable in Virginia. For more information about disease reporting, please visit VDH Disease Reporting and Control Regulations. Questions about disease reporting should be directed to your local health department.
Standardized surveillance case definitions are used to determine if a reported case meets specific criteria to be included in case counts for the purposes of public health surveillance. Case definitions usually rely on a combination of clinical, laboratory, and epidemiologic criteria to evaluate the strength of the evidence and then classify the reported case as either a confirmed case, probable case, suspect case, or not a case. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.
General Considerations for Tickborne Diseases
Exposure to ticks can occur from outdoor activities or from exposure to pets that spend time outdoors. People who are active outdoors (especially in certain habitats) have a higher probability of tick exposure. Up to half of all people bitten by a tick do not remember being bitten.
Diagnostic considerations presented below should not replace clinical judgment when managing an individual patient for whom tickborne disease is part of a differential diagnosis.
Antibodies to many infectious causes of tickborne diseases take an average of 7-10 days following illness onset to reach detectable levels and a negative result during the first week of illness is common. A measurable titer in the first week of illness is generally reflective of past exposure and not current illness.
Antibodies for many infectious causes of tickborne diseases remain elevated for months to years after initial infection. Serial antibody monitoring should not be used to assess if a person is "cured," and persistently elevated titers do not indicate ongoing infection.
Disease-Specific Information and Considerations*
*indicates which diseases are reportable in Virginia
Alpha-Gal Syndrome (Red Meat Allergy)
Alpha-gal syndrome (AGS) is an allergy to mammalian meat or meat products and is not currently a reportable disease in Virginia. AGS is associated with the lone star tick (Amblyomma americanum). Clinical manifestations of AGS can range from mild to severe and are characterized by a delayed reaction to mammalian meat (e.g., 3-6 hours after ingestion). Symptoms may include hives, angioedema, diarrhea, vomiting, and anaphylaxis.
- Commercially available blood testing for alpha-gal-specific IgE is widely available in the United States.
- In a patient with compatible symptoms, measurement of alpha-gal–specific IgE antibodies >0.1 IU/mL is widely considered a positive test result.
- CDC Clinical Testing and Diagnosis for Alpha-gal Syndrome
- CDC Alpha-gal Clinical Resources *(includes a continuing education opportunity)
- Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis — United States. MMWR Recomm Rep 2016;65(No. RR-2):1–44. DOI: http://dx.doi.org/10.15585/mmwr.rr6502a1
- Thompson JM, Carpenter A, Kersh GJ, Wachs T, Commins SP, Salzer JS. Geographic Distribution of Suspected Alpha-gal Syndrome Cases — United States, January 2017–December 2022. MMWR Morb Mortal Wkly Rep 2023;72:815–820. DOI: http://dx.doi.org/10.15585/mmwr.mm7230a2.
- Commins, SP. Diagnosis & management of alpha-gal syndrome: lessons from 2,500 patients. Expert Review Clinical Immunology. 2020;16(7):667-677. DOI: 10.1080/1744666X.2020.1782745
Anaplasmosis*
Anaplasmosis is a bacterial disease caused by Anaplasma phagocytophilum and is reportable in Virginia. Anaplasma phagocytophilum is transmitted by the blacklegged tick (Ixodes scapularis). Illness onset is typically 5-14 days after the bite of an infected tick. Signs and symptoms include fever, chills, headache and myalgia.
- Molecular methods, like polymerase chain reaction (PCR), are most accurate within the first 14 days of illness, while the patient is still symptomatic.
- The accuracy of PCR decreases following administration of antibiotics.
- Although a positive PCR result is helpful, a negative result does not rule out the diagnosis, and treatment should not be withheld due to a negative result.
- Paired serology with evidence of a fourfold rise in titer provides evidence of recent infection.
- If anaplasmosis is suspected, treatment with doxycycline should be started while waiting for test results.
Babesiosis*
Babesiosis is an emerging parasitic disease caused by Babesia spp and is reportable in Virginia. The organisms that cause babesiosis are transmitted by the blacklegged tick (Ixodes scapularis). Babesiosis can range in severity from asymptomatic to severe. Symptoms, if any, usually develop within a few weeks or months after exposure, although some patients may not manifest disease for many months. When clinical illness occurs, babesiosis is characterized by the presence of hemolytic anemia and nonspecific flu-like symptoms (e.g., fever, chills, body aches, weakness, fatigue).
- When considering acute illness with babesiosis as a differential diagnosis, healthcare providers should explicitly request a manual (non-automated) review of a peripheral blood smear or a polymerase chain reaction (PCR) test.
- The immunofluorescence assay (IFA) test is routinely used to detect B. microti antibody in blood. A B. microti IgG antibody titer of ≥1:1024 or the presence of B. microti IgM antibody are suggestive of active or recent B. microti infection, while a 4-fold rise in Babesia IgG antibody in sera from the time of acute illness to the time of convalescence confirms the diagnosis.
- CDC Clinical Overview of Babesiosis
- Krause PJ, Auwaerter PG, Bannuru RR, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA): 2020 Guideline on Diagnosis and Management of Babesiosis. Clinical Infectious Diseases, Volume 72, Issue 2, 15 January 2021, Pages e49–e64, https://doi.org/10.1093/cid/ciaa1216
- Swanson M, Pickrel A, Williamson J, Montgomery S. Trends in Reported Babesiosis Cases — United States, 2011–2019. MMWR Morb Mortal Wkly Rep 2023;72:273–277. DOI: http://dx.doi.org/10.15585/mmwr.mm7211a1.
- Locke S, O’Bryan J, Zubair AS, et al. Neurologic Complications of Babesiosis, United States, 2011–2021. Emerging Infectious Diseases. 2023;29(6):1128-1135. doi:10.3201/eid2906.221890.
Bourbon virus
Bourbon virus is a rare, emerging arbovirus that is not reportable in Virginia. Bourbon virus is possibly associated with the lone star tick (Amblyomma americanum). Patients with Bourbon virus have reported fever, fatigue, anorexia, nausea, vomiting, and maculopapular rash.
- Bourbon virus testing is currently only available via the CDC.
- Contact your local health department to inquire about Bourbon virus testing for patients with acute, compatible illness.
- CDC Clinical Diagnosis, Treatment, and Prevention of Bourbon Virus Disease
- Roe MK, Huffman ER, Batista YS, et al. Comprehensive Review of Emergence and Virology of Tickborne Bourbon Virus in the United States. Emerging Infectious Diseases. 2023;29(1):1-7. doi:10.3201/eid2901.212295.
- Kosoy OI, Lambert AJ, Hawkinson DJ, et al. Novel Thogotovirus Associated with Febrile Illness and Death, United States, 2014. Emerging Infectious Diseases. 2015;21(5):760-764. doi:10.3201/eid2105.150150.
Ehrlichiosis*
Ehrlichiosis is a bacterial disease caused by Ehrlichia spp and is reportable in Virginia. The organisms that cause ehrlichiosis are transmitted by the lone star tick (Amblyomma americanum). Illness onset is typically 5-14 days after the bite of an infected tick. Signs and symptoms include fever, chills, headache, myalgia and gastrointestinal symptoms, like nausea and vomiting.
- Polymerase chain reaction (PCR) on whole blood is the preferred diagnostic test and there are highly specific and sensitive PCR tests available from commercial laboratories.
- Molecular methods, like PCR, are most accurate within the first 14 days of illness while the patient is still symptomatic.
- The accuracy of PCR decreases following administration of antibiotics.
- Although a positive PCR result is helpful, a negative result does not rule out the diagnosis, and treatment should not be withheld due to a negative result.
- Paired serology with evidence of a fourfold rise in titer provides evidence of recent infection.
- If ehrlichiosis is suspected, treatment with doxycycline should be started while waiting for test results.
Image from Rickettsial Disease Diagnostic Testing and Interpretation for Healthcare Providers [Video]. CDC, 2021. Accessed June 2024. https://www.cdc.gov/rocky-mountain-spotted-fever/hcp/toolkit/index.html
- CDC Clinical Care of Ehrlichiosis
- CDC Ehrlichiosis Healthcare Providers
- CDC Ehrlichiosis Publication (includes continuing education credit opportunity)
Heartland*
Heartland virus is a rare, emerging arbovirus and, as an arboviral infection, is reportable in Virginia. Heartland virus is associated with the lone star tick (Amblyomma americanum). Initial symptoms of Heartland virus disease are very similar to those of ehrlichiosis, which include fever, fatigue, anorexia, nausea, and diarrhea.
- Heartland virus testing is currently only available via the CDC.
- Contact your local health department to inquire about Heartland virus testing for patients with acute, compatible illness.
Lyme Disease*
Lyme disease is caused by the bacterium Borrelia burgdorferi and rarely, Borrelia mayonii; it is reportable in Virginia. Lyme disease is transmitted by the blacklegged tick (Ixodes scapularis). Early Lyme disease can present with a rash (erythema migrans), fever, chills, malaise, fatigue, headache, myalgia, arthralgia, and lymphadenopathy. Disseminated (untreated) Lyme disease can have dermatologic, neurologic, cardiac, and rheumatologic manifestations. B. mayonii can also cause nausea and vomiting, as well as large, widespread rashes.
- For patients who present with an expanding skin rash called erythema migrans (EM) after being in a state where Lyme disease is common, like Virginia, Lyme disease should be diagnosed clinically (without diagnostic testing). Serologic tests might be negative during the first few weeks of infection while detectable antibodies are developing.
- Use the two-step serologic testing method, as it is more sensitive and specific.
- Use IgG results to guide diagnosis if a patient has been ill for more than 30 days.
- Infection with B. mayonii can be specifically identified by Lyme disease molecular tests available through Mayo Clinic Laboratories.
Image from Lyme Disease Serologic Testing . CDC, 2022. Access June 2024. https://www.cdc.gov/lyme/hcp/communication-resources/
- CDC Clinical Care of Lyme Disease
- CDC Clinical Testing and Diagnosis for Lyme Disease
- CDC Lyme Disease Continuing Education
- Tickborne Diseases of the United States: A Reference Manual for Healthcare Providers. sixth edition, 2022.
- CDC Pretest Probability of Lyme Disease Poster
- CDC Lyme Disease Prophylaxis After Tick Bite Poster
- Suggested Reporting Language, Interpretation and Guidance Regarding Lyme Disease Serology Test Results
Powassan Virus*
Powassan virus is a rare, emerging arbovirus and is reportable in Virginia. Powassan virus is associated with the blacklegged tick (Ixodes scapularis). The incubation period for Powassan virus disease ranges from 1–4 weeks. Initial symptoms include fever, headache, vomiting, and generalized weakness. The disease can progress to encephalitis, meningoencephalitis, or aseptic meningitis.
- Diagnosis is generally accomplished by testing of serum or cerebrospinal fluid (CSF) to detect Powassan virus-specific IgM and neutralizing antibodies.
- Molecular tests to detect viral RNA (e.g., PCR) can be performed on serum, CSF, and tissue specimens that are collected early in the course of illness and, if available, at some state public health and reference laboratories.
- Contact your local health department to inquire about Powassan virus testing for patients with acute, compatible illness.
Spotted Fever Rickettsioses (including Rocky Mountain Spotted Fever [RMSF]) *
All spotted fever rickettsioses (SFR), which include RMSF and Rickettsia parkeri rickettsiosis, are reportable in Virginia. These diseases have been primarily associated with the American dog (Dermacentor variabilis) and Gulf Coast (Amblyomma maculatum) ticks, but other ticks, such as the lone star tick (Amblyomma americanum), are being investigated as possible vectors. Illness onset with RMSF is typically 3-12 days after the bite of an infected tick. Signs and symptoms include fever, headache, gastrointestinal symptoms like nausea and vomiting, and a rash that typically appears 2-4 days after the onset of fever. Rickettsia parkeri infections have a similar incubation period as RMSF and similar symptoms but are characteristically less severe than RMSF and are almost always associated with an inoculation eschar at the site of tick attachment.
- Treatment with doxycycline should be initiated as soon as RMSF or other rickettsial infections are suspected – do not wait for confirmatory diagnostic testing.
- Immunofluorescence assay (IFA) tests that measure IgG-specific antibody titers are widely available and preferred as they provide quantitative results. A fourfold rise in serum titers collected 2-4 weeks apart provides the best evidence of recent infection.
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- IFA results early in the course of disease will often be negative.
- IFA cannot provide species-specific results to distinguish among species of Rickettsia.
- IgG antibodies are a more reliable indicator of exposure than IgM antibodies. IgM antibodies should not be used alone to diagnose rickettsial disease.
- Polymerase chain reaction (PCR) can be used to amplify Rickettsia spp DNA from whole blood, eschars, and rashes.
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- Rickettsia rickettsii might not circulate in large numbers in whole blood until disease is severe.
- In Virginia, Rickettsia amblyommatis, a nonpathogenic species of Rickettsia, is commonly found in lone star ticks. Exposure to this species of Rickettsia from the bite of a lone star tick can create antibodies that cross react with pathogenic species, like Rickettsia rickettsii.
Image from Rickettsial Disease Diagnostic Testing and Interpretation for Healthcare Providers . CDC, 2021. Accessed June 2024. https://www.cdc.gov/rocky-mountain-spotted-fever/hcp/toolkit/index.html
- CDC Clinical Care of Other Spotted Fever Rickettsioses
- Rocky Mountain Spotted Fever (RMSF) | CDC
- Other Spotted Fever Group Rickettsioses | Other Spotted Fevers | CDC
- Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis — United States. MMWR Recomm Rep 2016;65(No. RR-2):1–44. DOI: http://dx.doi.org/10.15585/mmwr.rr6502a1.
Southern Tick-Associated Rash Illness (STARI)
STARI is associated with the lone star tick (Amblyomma americanum) and is not reportable in Virginia. Patients with STARI develop a circular rash similar to the rash of early Lyme disease. These patients may also develop fatigue, headache, fever, and muscle pains. The cause of this rash has not been determined; however, studies have shown that the rash is not caused by Borrelia burgdorferi.
- STARI is diagnosed based on symptoms, geographic location, and possibility of a tick bite.
- Because the cause of STARI is unknown, no diagnostic blood tests have been developed.
Tularemia*
Tularemia is a bacterial disease caused by Francisella tularensis and is reportable in Virginia. Francisella tularensis is spread by several species of ticks, deer flies, contact with infected carcasses or animals (such as rabbits, hares, and rodents), contaminated food or water, or inhalation of aerosols (such as by mowing over an infected rabbit carcass). Tularemia symptoms vary depending on how a patient is exposed, although all forms are accompanied by fever, which can be as high as 104 °F. The most common form of tularemia infection is ulceroglandular, which results in a skin ulceration at the site of bacterial entry and enlarged, regional lymph nodes.
- Alert the laboratory prior to submitting clinical specimens if tularemia is suspected, as special diagnostic and safety procedures might be needed.
- Cultures for tularemia need to be incubated for extended periods due to the slow growing nature of this bacterium.
- Tularemia can also be diagnosed with evidence of seroconversion from negative to positive IgM and/or IgG antibodies in paired sera collected 2-3 weeks apart.
Links for more information and training opportunities:
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