Babesia Anemia: Can Babesiosis Destroy Red Blood Cells?

Babesia infects red blood cells and may cause hemolytic anemia.
Rarely, it can trigger autoimmune hemolytic anemia.
Early diagnosis and treatment may improve outcomes.

Babesia anemia occurs when Babesia microti infects red blood cells and causes them to rupture, a process known as hemolysis. Most cases result from direct destruction of infected red blood cells, while autoimmune hemolytic anemia is a much rarer complication.

Babesia is one of the few tick-borne infections that directly infects red blood cells. As the parasite multiplies inside these cells, it can destroy them, leading to anemia and other complications. In rare cases, the infection may also trigger autoimmune hemolytic anemia (AIHA).

Autoimmune hemolytic anemia is a rare disorder in which antibodies mistakenly attack a person’s own red blood cells, leading to their destruction and a reduced red blood cell count. AIHA has only rarely been associated with Babesia infection.

Bleik and Matubia described this uncommon presentation in their article, “Warm Autoimmune Hemolytic Anemia Secondary to Babesia Microti Infection: A Case Report.”

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Can Babesia Cause Anemia?

Yes. Babesia infects red blood cells, where the parasite reproduces before causing the cells to rupture. This destruction of red blood cells, known as hemolysis, can lead to anemia.

In my clinical practice, clinically significant anemia is most likely to be identified early in babesiosis, before the infection has been recognized and treated. By the time many patients are referred for evaluation of persistent Lyme disease and Babesia co-infection, they often no longer have clinically significant anemia, even though other Babesia symptoms may persist.

Most Babesia-related anemia results from direct destruction of infected red blood cells. In rare cases, Babesia infection may also trigger warm autoimmune hemolytic anemia, in which the immune system attacks red blood cells in addition to the parasite itself.

Although autoimmune hemolytic anemia is uncommon, clinicians should consider babesiosis in patients with unexplained hemolytic anemia who have lived in or traveled to tick-endemic areas.

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How Babesia Destroys Red Blood Cells

Babesia microti lives inside red blood cells. As the parasite multiplies, infected red blood cells rupture, releasing parasites that infect additional red blood cells. This ongoing cycle of infection can lower the red blood cell count and contribute to anemia.

The severity of anemia often correlates with the degree of parasitemia, although even relatively low parasite burdens may occasionally trigger significant immune-mediated hemolysis.

Hemolysis refers to the destruction of red blood cells. In babesiosis, hemolysis most commonly results from direct infection of red blood cells by the parasite. In rare cases, autoimmune mechanisms may also contribute.

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Symptoms of Babesia-Related Anemia

Patients with Babesia anemia may develop symptoms related to both infection and red blood cell destruction. Symptoms may include:

• Fatigue
• Weakness
• Lightheadedness
• Shortness of breath
• Rapid heart rate
• Pale skin
• Jaundice
• Dark urine
• Fever or chills
• Night sweats
• Muscle or joint pain

Some patients also develop thrombocytopenia (a low platelet count) in addition to anemia.

For related symptoms, see Babesia and Lyme Disease and Night Sweats and Lyme Disease.

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Case Report: Babesia and Autoimmune Hemolytic Anemia

An elderly man with an intact spleen was admitted to the hospital with fatigue, lightheadedness, shoulder and hip pain, and abdominal discomfort that had persisted for two weeks.

He also reported difficulty urinating, one episode of chills, and pain in his lower left back.

Laboratory testing revealed acute anemia and mild thrombocytopenia.

Because he had spent time outdoors in a tick-endemic region, clinicians ordered testing for Lyme disease and other tick-borne infections.

Blood testing was positive for Babesia microti. The authors concluded that the final diagnosis was warm autoimmune hemolytic anemia secondary to babesiosis.

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A Rare Presentation in a Patient With an Intact Spleen

The authors emphasized that this represented a rare case of babesiosis-associated warm autoimmune hemolytic anemia occurring in an immunocompetent individual with a functioning spleen.

Babesiosis is generally more severe in older adults, immunocompromised individuals, and patients without a spleen. However, this report demonstrates that Babesia-associated autoimmune hemolytic anemia can occasionally occur even in immunocompetent patients whose spleens are intact.

The authors advised clinicians to consider babesiosis in elderly patients presenting with warm autoimmune hemolytic anemia, particularly when they have lived in or traveled to endemic regions.

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Babesia May First Be Discovered Through Blood Donation

Not every Babesia infection is diagnosed when symptoms first appear. In my practice, several patients learned they had Babesia only after donating blood. The blood recipient developed transfusion-transmitted babesiosis, prompting an investigation that ultimately identified the donor as having an unrecognized infection.

Because Babesia microti infects red blood cells, the parasite can survive in donated blood and be transmitted through transfusion. Transfusion-transmitted babesiosis is now a recognized public health concern in the United States and has led to routine donor screening in many endemic regions.

These cases illustrate that Babesia infection may remain unrecognized for prolonged periods and does not always present with severe anemia at the time of diagnosis.

For more on this issue, see Patient Contracts Babesia From Blood Donor.

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Treatment for Babesia-Associated Anemia

The patient’s symptoms resolved completely following treatment with atovaquone and azithromycin, together with prednisone.

In Babesia-associated warm autoimmune hemolytic anemia, standard antimicrobial therapy may be sufficient to control hemolysis in some patients. However, additional immunosuppressive therapy for autoimmune hemolytic anemia may be necessary when immune-mediated destruction of red blood cells is severe.

Patients with mild disease may be treated as outpatients, while severe hemolysis, high parasitemia, or evidence of organ dysfunction may require hospitalization.

Treatment decisions depend on the severity of anemia, the degree of hemolysis, the patient’s immune status, and whether complications such as thrombocytopenia, persistent parasitemia, or organ dysfunction are present.

Severe babesiosis may occasionally require exchange transfusion in addition to antimicrobial therapy, particularly in patients with high parasitemia or evidence of end-organ dysfunction.

For more on treatment considerations, see Babesia Treatment.

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Can Lyme Disease Cause Anemia?

Patients often ask whether Lyme disease itself can cause anemia. Lyme disease is not considered a common cause of hemolytic anemia, making Babesia an important consideration whenever anemia accompanies tick-borne illness.

Babesia, a tick-borne co-infection that may occur alongside Lyme disease, is a far more common cause of hemolytic anemia because it directly infects red blood cells.

When a patient with suspected Lyme disease develops anemia, thrombocytopenia, jaundice, dark urine, air hunger, sweats, or profound fatigue, clinicians should consider Babesia and other tick-borne infections in the differential diagnosis.

For a broader overview, see Lyme Disease Co-Infections.

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Why Early Recognition Matters

As reported cases of babesiosis continue to increase, clinicians are likely to encounter more atypical presentations. Babesia-associated anemia may be overlooked if attention is focused solely on Lyme disease testing or if hemolysis is attributed to another cause.

Early recognition is important because untreated babesiosis can become severe, particularly in older adults and immunocompromised patients. Some individuals require urgent antimicrobial therapy, close monitoring, hospitalization, or exchange transfusion.

At the same time, many patients diagnosed later in the course of Babesia infection no longer have clinically significant anemia when they present for outpatient evaluation. The absence of anemia does not rule out Babesia, particularly when symptoms such as sweats, air hunger, fatigue, or relapsing illness persist.

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Frequently Asked Questions

Can Babesia cause anemia?

Yes. Babesia infects red blood cells and causes them to rupture, a process known as hemolysis. This can lead to anemia along with fatigue, weakness, dizziness, jaundice, dark urine, and shortness of breath.

Can babesiosis cause hemolytic anemia?

Yes. Hemolytic anemia is a recognized complication of babesiosis because the parasite lives inside red blood cells and destroys them as it reproduces.

Can Babesia cause autoimmune hemolytic anemia?

Rarely. Babesia infection has been reported to trigger warm autoimmune hemolytic anemia, in which the immune system attacks red blood cells in addition to those infected by the parasite.

Can Lyme disease cause anemia?

Lyme disease itself is not considered a common cause of hemolytic anemia. However, Babesia, an important Lyme disease co-infection, is a far more common cause because it directly infects red blood cells.

Can Babesia cause low platelets?

Yes. Babesiosis commonly causes thrombocytopenia (low platelets), particularly in moderate to severe disease.

Can you have Babesia without anemia?

Yes. Many patients diagnosed later in the course of infection no longer have clinically significant anemia, even though symptoms such as sweats, air hunger, fatigue, and relapsing illness persist.

What blood count changes are seen with Babesia?

Babesiosis may cause anemia, thrombocytopenia, elevated bilirubin, elevated LDH, low haptoglobin, and parasites visible inside red blood cells on peripheral blood smear.

How is Babesia-related anemia treated?

Treatment generally includes atovaquone plus azithromycin. Severe disease may require hospitalization, exchange transfusion, or additional immunosuppressive therapy if autoimmune hemolytic anemia develops.

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Clinical Takeaway

Babesia is one of the few tick-borne infections that directly infects red blood cells, making hemolytic anemia a hallmark complication. Although warm autoimmune hemolytic anemia remains rare, clinicians should consider babesiosis when patients present with unexplained anemia, thrombocytopenia, or evidence of hemolysis following tick exposure. At the same time, many patients diagnosed later in the course of infection no longer have clinically significant anemia, so the absence of anemia does not exclude Babesia.

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Related Articles

Learn more about Babesia Symptoms and Treatment.

Read about Patient Contracts Babesia From Blood Donor.

Review Neurologic Complications of Babesia.

Learn when Air Hunger May Suggest Babesia.

Explore Lyme Disease Co-Infections.

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References

1. Bleik P, Matubia V. Warm Autoimmune Hemolytic Anemia Secondary to Babesia Microti Infection: A Case Report. Cureus. 2023;15(12):e50294. doi:10.7759/cureus.50294.
2. Sanchez E, Vannier E, Wormser GP, Hu LT. 2020 Guidelines for the Prevention, Diagnosis and Treatment of Babesiosis. Clin Infect Dis. 2021;72(2):e49-e64.
3. U.S. Food and Drug Administration. Recommendations to Reduce the Risk of Transfusion-Transmitted Babesiosis. Updated 2024.
4. Kulu UA, Kalkan IA, Keskin H. Lyme disease as a rare trigger for autoimmune hemolytic anemia. BMC Infect Dis. 2026;26:231. doi:10.1186/s12879-025-12486-x. PMID: 41484709; PMCID: PMC12866312.
5. Tole MC, Perez MV, Mekonen YF, Bermudez M, Salazar H. Cohabitating in the City: A Case of Hemolytic Anemia in a Patient Coinfected With Babesiosis, Lyme Disease, and Mononucleosis. Cureus. 2025;17(4):e83043. doi:10.7759/cureus.83043. PMID: 40432655; PMCID: PMC12105930.

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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