Babesia and Anaplasmosis Coinfection: When Two Tick Infections Cause Confusion

Babesia and Anaplasmosis coinfection can lead to serious illness, particularly in older adults. In this Inside Lyme case study, I discuss a 78-year-old woman who presented with confusion and fever caused by two tick-borne infections occurring at the same time.

Paparone and colleagues described this case in the journal Nurse Practitioner.

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Babesia Symptoms and Anaplasmosis Causing Confusion

A 78-year-old woman was evaluated in the emergency room with fever, chills, lethargy, fatigue, and confusion. Her maximum temperature was 100.6°F.

Her blood tests revealed significant abnormalities:

1. Anemia (hemoglobin dropped from 10.5 g/dL to 8 g/dL)
2. Leukopenia (white blood cell count dropped from 5.0 × 10⁹/L to 2.6 × 10⁹/L)
3. Thrombocytopenia (platelets fell to 39 × 10⁹/L)

Because of her fever and abnormal laboratory findings, doctors initially suspected sepsis — a potentially life-threatening illness triggered by infection.

The patient also reported multiple tick bites.

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Diagnosing Babesia and Anaplasmosis Coinfection

The physicians identified the parasite that causes Babesia inside the patient’s red blood cells using microscopy. Babesia microti is transmitted by the same tick that spreads Lyme disease.

The doctors began treatment for Babesia with atovaquone and azithromycin, medications commonly marketed as Mepron and Zithromax.

However, the patient’s low white blood cell count and low platelet count raised concern for another tick-borne illness: Anaplasmosis (formerly called Ehrlichiosis).

Because standard Babesia treatment does not treat Anaplasmosis, doctors added doxycycline.

Laboratory testing confirmed a Babesia and Anaplasmosis coinfection. IgM antibodies were positive for both infections, suggesting early disease.

The patient’s confusion improved dramatically after two weeks of treatment.

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Why Babesia–Anaplasmosis Coinfection Can Be Dangerous

This case highlights several important lessons about tick-borne coinfections:

1. Tick-borne infections can cause confusion, especially in elderly patients.
2. Babesia and Anaplasmosis may initially be mistaken for sepsis.
3. Babesia and Anaplasmosis require different treatments.
4. Standard Babesia therapy (atovaquone and azithromycin) does not treat Anaplasmosis.

If physicians had not suspected Anaplasmosis and added doxycycline, this patient might have had a much worse outcome.

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Babesia Symptoms in Elderly Patients

Babesia symptoms can vary widely and may be more severe in older adults. Common symptoms include fever, chills, fatigue, anemia, and confusion. In this case, the patient’s confusion and abnormal blood counts were important clues that a tick-borne infection was present.

Babesia symptoms often overlap with other illnesses such as sepsis, influenza, or other tick-borne diseases like Anaplasmosis. When patients have multiple infections at the same time, diagnosis can become even more challenging.

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Questions Raised by This Case

1. How often are elderly patients with tick-borne infections misdiagnosed because of confusion?
2. If Babesia parasites had not been seen under the microscope, would Babesia testing have been ordered?
3. What might have happened if physicians had not suspected Anaplasmosis?
4. Could short-term confusion from tick-borne infection lead to long-term cognitive problems?

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Clinical Perspective

In my practice, each patient requires a careful and individualized assessment. I order a broad range of blood tests to evaluate other medical conditions in addition to tick-borne infections and arrange consultations with specialists when needed.

Many patients with tick-borne illness are medically complex, as highlighted in this Inside Lyme podcast series.

Physicians evaluating elderly patients with unexplained confusion should consider tick-borne infections — especially Babesia coinfection — as part of the diagnostic evaluation.

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Frequently Asked Questions

Can Babesia and Anaplasmosis cause confusion?

Yes. Tick-borne infections such as Babesia and Anaplasmosis can cause fever, fatigue, and confusion. In this case, the patient’s cognitive symptoms improved after treatment.

What is the difference between Babesia and Anaplasmosis treatment?

Babesia is treated with atovaquone and azithromycin, while Anaplasmosis requires doxycycline. Patients with both infections must receive treatment for both diseases.

How are Babesia and Anaplasmosis diagnosed?

Babesia may be seen on a blood smear or detected by PCR testing. Anaplasmosis is often suspected when patients have low white blood cell and platelet counts and is confirmed with antibody or PCR testing.

Can tick-borne infections mimic sepsis?

Yes. Babesia and Anaplasmosis can cause fever, abnormal blood counts, and organ dysfunction — symptoms that may initially resemble sepsis.

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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