Can Anaplasmosis Cause Heart Problems? What Research Shows
Rare cardiovascular complications of anaplasmosis
How Lyme disease coinfection may complicate diagnosis
Why early recognition and doxycycline remain important
Anaplasmosis heart problems are uncommon, but published case reports have described myocarditis, myopericarditis, heart rhythm abnormalities, conduction disturbances, and pulmonary embolism associated with human granulocytic anaplasmosis. Most people recover with prompt doxycycline treatment, but these reports remind clinicians to consider tick-borne infections when patients develop unexplained cardiac symptoms after tick exposure.
Anaplasmosis is caused by Anaplasma phagocytophilum, a bacterium transmitted by the blacklegged (Ixodes) tick. Because the same tick also carries Borrelia burgdorferi, coinfection with Lyme disease may occur after a single tick bite.
Typical symptoms include fever, chills, headache, muscle aches, fatigue, and abnormal liver tests. Severe disease is uncommon but may require hospitalization, particularly in older adults and immunocompromised individuals. Recent reports suggest that cardiovascular complications, although rare, deserve greater recognition.
For an overview of the infection, see Anaplasmosis: Symptoms, Diagnosis, and Treatment.
What cardiovascular complications have been reported?
Most clinicians associate tick-borne cardiac disease with Lyme carditis. However, published case reports and a recent literature review suggest that anaplasmosis can also rarely involve the cardiovascular system. Reported complications include:
- Myocarditis
- Myopericarditis
- Atrial fibrillation
- Cardiac conduction abnormalities
- Right ventricular dysfunction
- Pulmonary embolism
- Rare ischemic stroke
Nearly all reported cardiovascular complications have occurred in hospitalized patients with acute illness rather than in routine outpatient practice. Because most published evidence consists of individual case reports and small case series, the true frequency of anaplasmosis heart problems remains uncertain.
A rare case of tick-borne myopericarditis
Arshad and colleagues reported a 61-year-old man from New Jersey who presented with a two-week history of fever, chills, muscle aches, nausea, vomiting, diarrhea, lightheadedness, and shortness of breath. During his evaluation, he recalled finding a tick on his clothing several weeks earlier. Laboratory testing ultimately demonstrated evidence of both acute anaplasmosis and Lyme disease. Epstein-Barr virus serology was also positive, creating an additional diagnostic challenge.
“This case highlights an uncommon presentation of carditis in acute Lyme and anaplasma infections with the associated false-positive serology of EBV.”
Electrocardiography demonstrated tachycardia with diffuse ST-segment elevations, while elevated cardiac troponin levels suggested myocardial injury. His illness progressed to septic shock requiring vasopressor support, and the investigators concluded that he had developed myopericarditis. Because both Lyme disease and anaplasmosis were documented, they could not determine with certainty which infection was primarily responsible for the cardiac inflammation.
Can anaplasmosis cause heart problems without Lyme disease?
A second report strengthened the evidence that anaplasmosis itself can occasionally involve the heart. Levy and colleagues described a 65-year-old man with confirmed human granulocytic anaplasmosis who developed shock, atrial fibrillation, conduction abnormalities, and cardiac MRI findings consistent with myopericarditis. Extensive testing found no evidence of acute Lyme disease. Following doxycycline treatment and supportive care, his cardiac function recovered and his heart rhythm returned to normal.
These two reports illustrate an important distinction. In one patient, Lyme disease coinfection made it difficult to determine which infection caused the cardiac inflammation. In the second patient, isolated anaplasmosis was sufficient to produce severe cardiac involvement, strengthening the evidence that Anaplasma phagocytophilum itself can rarely affect the heart.
Why coinfection can complicate the diagnosis
One challenge in interpreting published case reports is that patients may be infected with more than one tick-borne pathogen. Because Ixodes ticks can transmit Borrelia burgdorferi, Anaplasma phagocytophilum, Babesia microti, and other organisms during a single tick bite, determining which infection caused a particular complication is not always possible.
In the New Jersey case, both Lyme disease and anaplasmosis were diagnosed. The investigators concluded that the patient’s myopericarditis was most likely related to anaplasmosis but acknowledged that the contribution of Lyme disease could not be determined with certainty. False-positive Epstein-Barr virus (EBV) serology added another layer of diagnostic complexity.
By contrast, the 2023 European Heart Journal Case Reports case described myopericarditis with atrial fibrillation in a patient with confirmed anaplasmosis and no evidence of acute Lyme disease. Together, these reports suggest that although coinfection may contribute in some patients, Anaplasma phagocytophilum itself can rarely affect the heart.
Clinicians evaluating patients with possible tick-borne cardiac disease should also consider Lyme carditis, particularly when conduction abnormalities or other features of Lyme disease are present.
What does the newer research show?
A 2026 literature review expanded the spectrum of reported cardiovascular manifestations associated with anaplasmosis. In addition to myocarditis and myopericarditis, the authors identified reports of atrial fibrillation, conduction abnormalities, right bundle branch block, relative bradycardia, ischemic stroke, and an unusual case of pulmonary embolism. They concluded that these complications remain uncommon but may become increasingly recognized as the incidence of anaplasmosis continues to rise.
The review also noted that persistent tachycardia in a hospitalized patient should not automatically be attributed to fever or dehydration. In their featured case, persistent tachycardia prompted additional evaluation that led to the diagnosis of pulmonary embolism.
Although these reports expand our understanding of anaplasmosis heart problems, most published evidence consists of isolated case reports and small case series. Larger prospective studies are needed to determine how frequently cardiovascular complications occur and which patients are at greatest risk.
How are these patients treated?
Doxycycline remains the recommended first-line treatment for human granulocytic anaplasmosis and should be started promptly whenever the diagnosis is suspected. Supportive care may include intravenous fluids, treatment of shock when present, management of arrhythmias, anticoagulation for pulmonary embolism when indicated, and other therapies based on the patient’s clinical condition.
When cardiovascular complications occur, treatment is directed at both the underlying infection and the specific cardiac condition. Early recognition and prompt antibiotic therapy are associated with favorable outcomes in many published cases.
Frequently Asked Questions
Can anaplasmosis cause heart problems?
Yes, but they appear to be uncommon. Published reports describe myocarditis, myopericarditis, atrial fibrillation, conduction abnormalities, pulmonary embolism, and other cardiovascular complications in a small number of patients.
Is myocarditis common in anaplasmosis?
No. Most patients with anaplasmosis never develop cardiac involvement. Current evidence comes primarily from individual case reports and small case series.
Can Lyme disease and anaplasmosis occur together?
Yes. Because the same Ixodes tick can transmit both infections, coinfection is well recognized and may complicate the diagnosis and interpretation of cardiac complications.
Does doxycycline treat anaplasmosis?
Yes. Doxycycline is the recommended first-line antibiotic for human granulocytic anaplasmosis and should be started promptly when the disease is suspected.
Clinical Takeaway
Cardiovascular complications of anaplasmosis appear to be uncommon but are increasingly recognized in the medical literature. Published reports have described myocarditis, myopericarditis, atrial fibrillation, conduction abnormalities, and rare thrombotic complications such as pulmonary embolism. Most evidence comes from hospitalized patients with severe acute illness rather than routine outpatient practice.
In my office-based practice over nearly four decades of treating tick-borne illnesses, I have rarely encountered the severe cardiovascular complications described in these reports. Most patients I evaluate are seen before developing the critical illness reported in hospitalized cases. In addition, some published reports involve Lyme disease coinfection, making it difficult to determine whether the cardiac findings were caused by anaplasmosis alone or by the combined effects of multiple tick-borne infections.
Nevertheless, unexplained myocarditis, new arrhythmias, conduction disturbances, or persistent tachycardia after possible tick exposure should prompt consideration of anaplasmosis, Lyme disease, and other tick-borne infections. Early recognition and prompt doxycycline treatment remain essential.
Related Articles
Can Lyme Disease Cause Heart Problems?
Lyme Disease Coinfections: Why More Than One Tick-Borne Infection Matters
Babesia and Lyme Disease: Symptoms, Diagnosis, and Treatment
Lyme Disease Symptoms: A Complete Guide
References
- Arshad H, Oudah B, Mousa A, et al. Tick-Borne Myopericarditis With Positive Anaplasma, Lyme, and Epstein-Barr Virus (EBV) Serology: A Case Report. Cureus. 2023;15(6):e40440.
- Levy AM, Martin LM, Krakower DS, Grandin EW. Case Report: Human Granulocytic Anaplasmosis Causes Acute Myopericarditis With Atrial Fibrillation. Eur Heart J Case Rep. 2023;7(1):ytad026.
- Gavrancic A, Jacobson CM, Rabasovic V, et al. Cardiovascular Complications of Anaplasmosis: A Case of Acute Pulmonary Embolism and Literature Review. Infect Dis Rep. 2026;18(3):62.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
