Anaplasmosis and Lyme Disease: Symptoms & Treatment
Anaplasmosis and Lyme disease can occur together after the same tick bite, producing an acute febrile illness with high fever, severe headache, and characteristic laboratory abnormalities.
The same black-legged tick that transmits Lyme disease can also carry Anaplasma phagocytophilum, the bacterium responsible for anaplasmosis. When present, this coinfection can make patients feel significantly sicker, much earlier, than expected with Lyme disease alone.
For a broader overview, see our coinfections hub.
What Is Anaplasmosis?
Anaplasmosis is a bacterial infection transmitted by Ixodes scapularis ticks—the same black-legged ticks that transmit Lyme disease, Babesia, and other coinfections. The bacteria infect white blood cells, particularly neutrophils, disrupting immune function and producing characteristic laboratory abnormalities.
Unlike Lyme disease, which may develop gradually, anaplasmosis typically presents as an acute illness within 1–2 weeks of a tick bite, often with abrupt onset and systemic symptoms.
In earlier clinical literature, anaplasmosis was often classified as a form of ehrlichiosis (formerly called human granulocytic ehrlichiosis). This historical overlap contributes to ongoing confusion in terminology, particularly when comparing ehrlichiosis and anaplasmosis.
Anaplasmosis Symptoms
Anaplasmosis presents as an acute febrile illness with symptoms appearing suddenly and progressing rapidly.
- High fever (often 102–104°F)
- Severe headache
- Muscle aches and body pain
- Chills and rigors
- Nausea, vomiting, or diarrhea
- Fatigue and malaise
Unlike Lyme disease, anaplasmosis rarely produces a rash. The absence of rash combined with severe systemic symptoms can lead to misdiagnosis as influenza or other viral illness.
For a broader overview of symptom patterns, see our Lyme disease symptoms guide.
Laboratory Findings
Laboratory abnormalities can provide important diagnostic clues. Patients with anaplasmosis often have:
- Low white blood cell count (leukopenia)
- Low platelet count (thrombocytopenia)
- Elevated liver enzymes
The combination of acute fever and these laboratory findings in a patient with possible tick exposure should raise suspicion for anaplasmosis.
These challenges reflect broader issues discussed in Lyme testing limitations.
Neurologic Involvement
Although anaplasmosis is primarily an acute febrile illness, some patients may experience neurologic symptoms such as headache, confusion, or other changes that complicate the clinical picture.
More detailed neurologic involvement is discussed in Anaplasmosis in the brain. For a broader overview, see our coinfections hub.
Why Anaplasmosis Is Missed
Anaplasmosis is frequently misdiagnosed as viral illness, particularly influenza. The acute onset, high fever, and systemic symptoms can resemble flu more than typical Lyme disease.
Diagnosis may also be missed when clinicians do not ask about tick exposure or outdoor activity. Without this context, the connection to tick-borne illness may not be recognized.
Because of these limitations, diagnosis often depends on recognizing clinical patterns rather than relying on a single test result.
Anaplasmosis and Lyme Disease Together
Because anaplasmosis and Lyme disease are transmitted by the same tick, coinfection is possible. A single tick bite can deliver both pathogens simultaneously.
Patients with both infections may experience the acute febrile illness of anaplasmosis overlapping with the joint pain, neurologic symptoms, or fatigue associated with Lyme disease.
In some cases, symptoms may reflect overlapping effects of multiple infections rather than a single organism.
Other coinfections, such as Babesia or Bartonella, may also contribute to a more complex presentation.
Treatment and Recovery
Anaplasmosis typically responds rapidly to doxycycline. Many patients improve within 24–48 hours, with fever resolving and symptoms beginning to improve.
Because doxycycline is also used to treat Lyme disease, it often addresses both infections when coinfection is present.
Prompt treatment is important. Delayed therapy increases the risk of complications such as respiratory failure, kidney injury, bleeding disorders, or neurologic changes.
When to Suspect Anaplasmosis
Anaplasmosis should be considered in patients with acute febrile illness and possible tick exposure, particularly when laboratory findings include low white blood cells, low platelets, or elevated liver enzymes.
When clinical suspicion is high, treatment with doxycycline is typically started without waiting for confirmatory testing.
Clinical Takeaways
Anaplasmosis is an acute bacterial coinfection transmitted by the same ticks that carry Lyme disease. It often presents with high fever, severe headache, and characteristic laboratory abnormalities.
Because it can resemble viral illness, anaplasmosis is frequently missed unless clinicians consider tick-borne infection in the differential diagnosis.
Early recognition and treatment are important, as most patients improve rapidly with appropriate therapy.
Frequently Asked Questions
What are the main symptoms of anaplasmosis?
High fever, severe headache, muscle aches, chills, and fatigue appearing suddenly after a tick bite.
How is anaplasmosis different from Lyme disease?
Anaplasmosis presents as an acute febrile illness, while Lyme disease often develops more gradually and may include rash and migratory symptoms.
Can you have anaplasmosis and Lyme disease at the same time?
Yes. Both infections can be transmitted by the same tick in a single bite.
How is anaplasmosis treated?
Doxycycline is the standard treatment, and most patients improve quickly after starting therapy.
Is anaplasmosis dangerous?
When treated promptly, most patients recover. Delayed treatment can lead to serious complications.
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
