Babesia Blood Transfusion: How One Unit Changed Everything
Babesia can spread through blood transfusions
Patients without tick exposure may still become infected
Delayed diagnosis can worsen outcomes in vulnerable individuals
When we think of Babesia, we often picture tick bites and outdoor exposure in wooded areas. But Babesia can also spread silently through the blood supply.
A recent case highlights how one transfused unit of blood led to a serious Babesia infection in a patient with no known tick exposure.¹
A Mysterious Illness After Blood Transfusion
A 30-year-old man with sickle cell disease required chronic red blood cell exchanges approximately every 3 to 4 weeks since childhood.¹
Two months after a routine transfusion, he developed symptoms that initially appeared nonspecific:
- Fever and chills
- Headache
- Fatigue
- Loss of appetite
- Neck pain
- Photophobia
His condition progressively worsened, raising concern for a serious systemic illness.
A Surprising Diagnosis: Babesia Infection
Laboratory testing revealed Babesia parasites within his red blood cells. Serologic testing was positive for Babesia infection.¹
Borderline positive testing for Anaplasma phagocytophilum and Ehrlichia chaffeensis was also noted, although those infections were not treated because supportive symptoms were absent.
Babesia is typically transmitted by ticks, yet this patient reported no recent outdoor exposure or tick bite.
Clinicians then began investigating whether the infection could have been transfusion-related.
Can Babesia Be Spread Through Donated Blood?
Yes. Babesia parasites infect red blood cells and may be transmitted through contaminated blood transfusions.¹
Because Babesia infects red blood cells, infected donors may unknowingly transmit the parasite through blood transfusion even when they feel completely healthy.
Transfusion-transmitted babesiosis has become an important public health concern because asymptomatic donors may not realize they are infected.
Tracing the Infection to the Blood Supply
A donor lookback investigation revealed that over six months the patient had received 65 units of blood, including 7 units that had not been screened for Babesia.¹
One unscreened donor later tested positive for Babesia microti.
The donor lived in Ohio, a state not considered Babesia-endemic and therefore not subject to mandatory Babesia blood screening at that time.
The donor had no symptoms but reported outdoor activities including hiking and camping in Ohio, Tennessee, and North Carolina.
Why Transfusion-Transmitted Babesia Matters
This case highlights an important reality: Babesia is not only a tick-borne infection. It can also spread through blood transfusions.
Prior to implementation of Babesia blood donor screening programs, transfusion-transmitted babesiosis represented one of the leading infectious risks to the United States blood supply.¹
Patients requiring repeated transfusions, including individuals with sickle cell disease, may face increased vulnerability.
Learn more about Babesia and Lyme coinfections.
Why Geographic Assumptions Can Be Dangerous
In 2019, the FDA implemented Babesia blood donor screening requirements in selected high-incidence states including New York, Connecticut, Massachusetts, and Minnesota.
However, this case demonstrates how transfusion-transmitted Babesia may still occur outside traditionally recognized endemic regions.
Travel patterns, outdoor recreation, and shifting tick ecology may complicate geographic assumptions regarding risk.
Clinicians in non-endemic states may therefore be less likely to recognize Babesia promptly.
Delayed Diagnosis Can Increase Risk
Delayed recognition of Babesia can lead to severe complications, particularly in:
- Immunocompromised individuals
- Chronically transfused patients
- Older adults
- Patients with underlying hematologic disease
Fortunately, this patient improved after treatment with azithromycin and atovaquone.¹
However, delayed diagnosis in vulnerable patients may lead to more severe illness or prolonged recovery.
Learn more about delayed diagnosis in tick-borne illness.
Lessons From This Case
This case raises several important clinical and public health concerns:
- Babesia can spread through blood transfusion
- Patients may develop Babesia without tick exposure
- “Non-endemic” states may still carry risk
- Expanded screening policies may eventually be necessary
- Delayed diagnosis can worsen outcomes
It also serves as a reminder that infectious risks sometimes extend beyond traditional geographic assumptions.
Frequently Asked Questions
Can Babesia spread through blood transfusions?
Yes. Babesia parasites can be transmitted through infected blood transfusions.
Can someone get Babesia without a tick bite?
Yes. Babesia may spread through blood transfusion even when patients have no known tick exposure.
Can healthy blood donors carry Babesia?
Yes. Some infected donors may have no symptoms yet still carry Babesia parasites in their bloodstream.
What symptoms can transfusion-transmitted Babesia cause?
Symptoms may include fever, chills, fatigue, headache, loss of appetite, anemia, and systemic illness.
Who is most vulnerable to severe Babesia infection?
Immunocompromised individuals, older adults, and patients requiring repeated blood transfusions may be at increased risk.
Is blood screened for Babesia in every state?
No. Babesia blood donor screening policies vary by geographic region and risk assessment.
Clinical Takeaway
Babesia should remain part of the differential diagnosis in patients who develop unexplained fever, fatigue, or systemic illness after blood transfusion.
This case demonstrates that transfusion-transmitted Babesia can occur even in states not traditionally considered endemic.
Early recognition and treatment may help reduce complications, particularly in vulnerable patients requiring chronic transfusions.
Related Articles
These related articles explore Babesia transmission, coinfections, delayed diagnosis, and severe tick-borne illness presentations.
Lyme disease misdiagnosis
Babesia symptoms and treatment
Neurologic Lyme disease
Lyme disease symptoms guide
Persistent Lyme disease symptoms
References
- Costa B, et al. Transfusion-transmitted babesiosis in a patient with sickle cell disease undergoing chronic red cell exchange. Int Med Case Rep J. 2020;13:575-579.
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
