Heartland virus (HRTV) is an emerging tick-borne bandavirus (formerly classified as a phlebovirus) first identified in Missouri in 2009, transmitted by the Lone Star tick (Amblyomma americanum). It causes an acute febrile illness characterized by leukopenia, thrombocytopenia, and elevated hepatic transaminases. Over 60 cases spanning 14 states have been reported to the CDC, with a mortality rate of approximately 10–13%, predominantly in older adults with comorbidities. [1-4]
1. History
- Tick exposure: Ask specifically about tick bites or finding an attached tick within the prior 2 weeks — 88% of confirmed cases reported a tick on themselves before illness onset [3]
- Outdoor activities: Farming, hiking, hunting, yard work in wooded/brushy areas in the Midwest and southern US
- Timing: Illness onset occurs April through September, coinciding with Lone Star tick activity [3][5]
- Symptom characterization: Acute onset of fever, fatigue, decreased appetite, headache, myalgia, arthralgia, nausea, and diarrhea [5-6]
- Progression: Symptoms typically worsen over the first week; nadir of cytopenias around days 5–7 of illness, with aminotransferase spike around days 7–8 [2]
- Important negatives: Rash is generally absent (unlike ehrlichiosis/RMSF); no respiratory or renal involvement was noted in the index cases [2]
2. Alarm Features
- Confusion or altered mental status — reported in a majority of confirmed cases [3]
- Hemorrhagic manifestations — hemorrhagic disease and DIC can occur in severe cases [4][7]
- Multiorgan failure — described in fatal cases [4][7]
- Severe neutropenia (ANC <700 cells/mm³) — nadirs around days 6–7 of hospitalization [2]
- Failure to improve on doxycycline — a key clinical clue distinguishing viral tick-borne illness from ehrlichiosis/anaplasmosis [3][8]
3. Medications
- No FDA-approved antiviral therapy exists for HRTV [1][5]
- Doxycycline is often empirically started for suspected tick-borne illness; lack of clinical improvement should raise suspicion for a viral etiology such as HRTV [3][8]
- Investigational agents: Favipiravir and 4'-fluorouridine (EIDD-2749) have shown efficacy in mouse models but are not approved for human use [1][9]
- Avoid: NSAIDs and anticoagulants should be used cautiously given thrombocytopenia and hemorrhagic risk
- Supportive medications: Antipyretics (acetaminophen preferred), antiemetics, IV fluids
4. Diet
- Hydration is critical, especially with fever, nausea, diarrhea, and decreased oral intake
- No specific dietary triggers or restrictions are associated with HRTV
- Patients with significant GI symptoms may benefit from a bland diet and small frequent meals
- Long-term dietary management is not applicable; this is an acute self-limited illness in most cases
5. Review of Systems
- Constitutional: Fever, fatigue, malaise, anorexia, weight loss
- Neurologic: Headache, confusion (common), altered mental status
- GI: Nausea, diarrhea, abdominal pain, vomiting
- MSK: Arthralgia, myalgia
- Hematologic: Easy bruising, petechiae, mucosal bleeding (suggests severe disease)
- Skin: Notably, rash is typically absent — its presence should prompt consideration of alternative diagnoses
- Respiratory/Renal: Generally not involved [2]
6. Collateral History and Family History
- Collateral: Confirm outdoor exposure history, geographic location (Midwest/southern US), timeline of tick exposure, and any known tick bites in household members or co-workers
- Immunocompromised status: Obtain history of immunosuppressive medications, malignancy, or chronic illness — these patients are at higher risk for severe outcomes [5]
- Family history: No hereditary predisposition; however, shared environmental exposures (e.g., family members with similar outdoor activities) may indicate co-exposure risk
- Occupational history: Farming, forestry, and outdoor recreation are high-risk activities [10]
7. Risk Factors
- Age: Median age of confirmed cases is 71 years (range 43–80); older age is significantly associated with infection (P < .001) [3]
- Sex: 75% of confirmed cases are male [3]
- Geography: Midwest and southern US, within the distribution range of Amblyomma americanum [5][11]
- Season: April through September (peak Lone Star tick activity) [3]
- Tick attachment: Significantly associated with infection (P = .03) [3]
- Comorbidities: Older individuals with medical comorbidities have the highest mortality risk [5]
- Immunosuppression: Likely increases severity based on animal model data [11]
8. Differential Diagnosis
- Ehrlichiosis (most important mimic) — also transmitted by Lone Star tick, causes fever/leukopenia/thrombocytopenia; responds to doxycycline [6][12]
- Anaplasmosis — similar lab findings; responds to doxycycline
- Rocky Mountain Spotted Fever — typically has rash; responds to doxycycline
- Bourbon virus disease — same vector, similar presentation; no specific treatment [13]
- Babesiosis — hemolytic anemia, parasitemia on smear
- Hematologic malignancy (leukemia, lymphoma) — persistent cytopenias without improvement
- Thrombotic thrombocytopenic purpura (TTP) — schistocytes, renal dysfunction
- Viral hemorrhagic fevers — travel history dependent
- Severe sepsis — broader infectious workup needed
- Key distinguishing feature: Failure to respond to doxycycline in a patient with suspected tick-borne illness should prompt HRTV testing [3][8]
9. Past Medical History
- Document any immunosuppressive conditions (cancer, organ transplant, HIV, chronic steroid use)
- Prior tick-borne illnesses or tick exposures
- Chronic liver disease (may worsen transaminase elevations)
- Bleeding disorders or anticoagulant use (increases hemorrhagic risk with thrombocytopenia)
- Chronic kidney disease, cardiovascular disease, diabetes — comorbidities associated with worse outcomes [5]
10. Physical Exam
- Vital signs: Fever (often high), tachycardia; hypotension in severe cases
- General: Ill-appearing, fatigued, cachectic appearance if prolonged illness
- Skin: Thorough skin survey for embedded ticks or tick bite sites; rash is typically absent
- HEENT: No specific findings; check for conjunctival pallor or petechiae
- Lymph nodes: May have mild lymphadenopathy (HRTV antigen detected in lymph nodes on autopsy) [7]
- Abdomen: Hepatomegaly or splenomegaly possible; splenomegaly noted in animal models [14]
- Neurologic: Assess for confusion, altered mental status — common in confirmed cases [3][7]
- Mucosal surfaces: Check for gingival bleeding, petechiae (hemorrhagic complications)
11. Lab Studies
- CBC with differential: Expect leukopenia (with neutropenia, ANC may drop below 700) and thrombocytopenia — these are hallmark findings [2][15]
- CMP/hepatic panel: Mild-to-moderate elevation of AST and ALT, typically spiking around days 7–8 of illness [2]
- Coagulation studies: PT/INR, PTT, fibrinogen — to evaluate for DIC (notably, coagulopathy was not prominent in the index cases, unlike SFTS) [2]
- Blood smear: To rule out babesiosis, TTP (schistocytes), and hematologic malignancy
- Blood cultures: To rule out bacterial sepsis
- Ehrlichia/Anaplasma PCR and serology: Critical to rule out treatable bacterial tick-borne infections [12]
- HRTV-specific testing: RT-PCR for viral RNA and IgM/IgG antibodies — available only through state health departments and the CDC; no commercial assays exist [5-6]
The following figure from the original NEJM description of HRTV illustrates the characteristic temporal evolution of laboratory values in the two index patients:
12. Imaging
- No specific imaging findings are characteristic of HRTV infection
- Chest X-ray: Obtain if respiratory symptoms are present to rule out pneumonia or ARDS, though respiratory involvement is not typical [2]
- CT head: Consider if altered mental status or confusion is prominent, to rule out intracranial hemorrhage (given thrombocytopenia) or encephalitis
- Abdominal imaging: Consider if hepatosplenomegaly or abdominal pain is present
- Imaging is generally guided by clinical presentation rather than routinely indicated
13. Special Tests
- HRTV RT-PCR: Detects viral RNA in acute blood specimens — most useful in the first ~2 weeks of illness [5-6]
- HRTV IgM/IgG serology: Microsphere-based immunoassays developed at CDC with >95% sensitivity and specificity; IgM indicates recent infection [12]
- Plaque reduction neutralization test (PRNT): Confirmatory serologic test
- Contact state health department: Required step for all suspected cases — CDC performs confirmatory testing [5]
- Peripheral blood smear: To exclude babesiosis and hematologic malignancy
14. ECG
- No specific ECG findings are associated with HRTV infection
- ECG should be obtained in patients with hemodynamic instability, electrolyte abnormalities, or significant comorbidities
- Monitor for arrhythmias in critically ill patients with multiorgan failure
15. Assessment
HRTV disease should be suspected in any patient presenting with acute febrile illness with leukopenia and/or thrombocytopenia in the Midwest or southern US during tick season, particularly if there is a history of tick exposure and failure to improve on doxycycline. [3][8]
- Typical presentation: Older male with outdoor exposure, fever, fatigue, anorexia, myalgia, and cytopenias
- Atypical presentations: May present with prominent confusion or GI symptoms; hemorrhagic disease and multiorgan failure represent the severe end of the spectrum [4][7]
- Severity stratification: Most patients require hospitalization (88%); mortality ~10–13%, concentrated in elderly patients with comorbidities [3][9]
- Complications: Hemorrhagic disease, DIC, multiorgan failure, prolonged hospitalization [4][7]
16. Treatment Plan
Initial stabilization
- IV fluid resuscitation for dehydration from fever, poor oral intake, and diarrhea
- Empiric doxycycline 100 mg PO/IV BID should be started immediately if tick-borne illness is suspected (covers ehrlichiosis/anaplasmosis while awaiting results) [6]
Supportive care (mainstay of HRTV treatment)
- Acetaminophen for fever and pain (avoid NSAIDs given thrombocytopenia)
- Antiemetics for nausea/vomiting
- Platelet transfusion if clinically significant bleeding or platelet count critically low
- Packed RBC transfusion if hemorrhage occurs
- Monitor and correct electrolyte abnormalities
No approved antivirals
- No FDA-approved antiviral therapy exists [1][5]
- Favipiravir and EIDD-2749 are investigational only [1][9]
Monitoring
- Serial CBC with differential (at least daily during hospitalization)
- Serial hepatic transaminases
- Coagulation studies if hemorrhagic signs develop
- Expect nadir of cytopenias around days 5–7 and transaminase peak around days 7–8, with recovery thereafter [2]
17. Disposition
- Admission criteria: Most patients (88%) require hospitalization; admit for significant cytopenias, inability to tolerate oral intake, confusion/AMS, hemodynamic instability, or hemorrhagic signs [3]
- ICU admission: Multiorgan failure, hemorrhagic disease, DIC, severe hemodynamic instability
- Observation: Mildly symptomatic patients with stable labs and adequate oral intake may be observed with close follow-up, though this is uncommon given typical severity
- Discharge criteria: Improving cytopenias (rising WBC and platelets), normalizing transaminases, afebrile, tolerating oral intake, no confusion
- Specialist consultation: Infectious disease consultation recommended for all suspected cases; hematology if cytopenias are severe or atypical; critical care for multiorgan failure
18. Follow Up / Return Precautions
- Follow-up: Recheck CBC and hepatic panel within 3–5 days of discharge to confirm continued recovery
- Expected recovery: Most immunocompetent patients fully recover with supportive care; convalescence may take weeks [5]
- Return precautions — instruct patients to return immediately for:
- Recurrent or worsening fever
- New confusion or altered mental status
- Signs of bleeding (gingival bleeding, petechiae, melena, hematuria)
- Inability to tolerate oral fluids
- Worsening fatigue or new symptoms
- Tick prevention counseling: Wear long sleeves and pants, use DEET-based repellents on skin and permethrin on clothing, perform tick checks after outdoor activity, bathe promptly, and dry clothing at high temperatures [6]
- Reporting: HRTV is a reportable condition — notify the state health department [5]
References
1. Modeling Heartland Virus Disease in Mice and Therapeutic Intervention With 4'-Fluorouridine. — Westover JB, Jung KH, Alkan C, et al. Journal of Virology. 2024.
2. A New Phlebovirus Associated with Severe Febrile Illness in Missouri. — McMullan LK, Folk SM, Kelly AJ, et al. The New England Journal of Medicine. 2012.
3. Investigation of Heartland Virus Disease Throughout the United States, 2013-2017. — Staples JE, Pastula DM, Panella AJ, et al. Open Forum Infectious Diseases. 2020.
4. Pathogenesis and Virulence of Heartland Virus. — Feng K, Bendiwhobel Ushie B, Zhang H, et al. Virulence. 2024.
5. Tickborne Diseases of the United States: A Reference Manual for Healthcare Providers Sixth Edition. — Nancy Shadick MD MPH, Nancy Maher MPH, Dennis Hoak MD United States Centers for Disease Control and Prevention (2022). 2022.
6. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Management of Tick-Borne Illness in the United States. — Ho BM, Davis HE, Forrester JD, et al. Wilderness & Environmental Medicine. 2021.
7. Heartland Virus-Associated Death in Tennessee. — Muehlenbachs A, Fata CR, Lambert AJ, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2014.
8. Dermatological Manifestations of Tick-Borne Viral Infections Found in the United States. — Rupani A, Elshabrawy HA, Bechelli J. Virology Journal. 2022.
9. Susceptibility of Type I Interferon Receptor Knock-Out Mice to Heartland Bandavirus (HRTV) Infection and Efficacy of Favipiravir and Ribavirin in the Treatment of the Mice Infected With HRTV. — Fujii H, Tani H, Egawa K, et al. Viruses. 2022.
10. Notes From the Field: Heartland Virus Disease - United States, 2012-2013. — Pastula DM, Turabelidze G, Yates KF, et al. MMWR. Morbidity and Mortality Weekly Report. 2014.
11. Heartland Virus Epidemiology, Vector Association, and Disease Potential. — Brault AC, Savage HM, Duggal NK, Eisen RJ, Staples JE. Viruses. 2018.
12. Development of Diagnostic Microsphere-Based Immunoassays for Heartland Virus. — Basile AJ, Horiuchi K, Goodman CH, et al. Journal of Clinical Virology : The Official Publication of the Pan American Society for Clinical Virology. 2021.
13. Emerging Tickborne Viruses Vectored by Amblyomma Americanum (Ixodida: Ixodidae): Heartland and Bourbon Viruses. — Dupuis AP, Lange RE, Ciota AT. Journal of Medical Entomology. 2023.
14. Vertebrate Host Susceptibility to Heartland Virus. — Bosco-Lauth AM, Calvert AE, Root JJ, et al. Emerging Infectious Diseases. 2016.
15. One Confirmed and 2 Suspected Cases of Heartland Virus Disease. — Decker MD, Morton CT, Moncayo AC. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2020.