Tick-Borne Infections and Blood Transfusions: What’s the Risk?

Tick-borne infections blood transfusion risk has become an increasing concern among researchers and public health experts.

In a summary of a U.S. Food and Drug Administration (FDA) workshop on emerging tick-borne diseases, experts reviewed the potential threat to blood safety. :contentReference[oaicite:0]{index=0}

The workshop brought together specialists from academia, blood centers, government agencies, and diagnostic companies to evaluate whether additional screening measures are needed.

Babesia: The Leading Concern

Babesia microti has been the most significant tick-borne threat to the blood supply to date.

At the time of the workshop, more than 200 cases of transfusion-transmitted Babesia infection had been reported in the United States.

Unlike some other pathogens, Babesia can reach high concentrations in the blood—making transmission through transfusion more likely.

Clinical concern: donors may be asymptomatic, allowing infection to go undetected.

Other Tick-Borne Pathogens in Blood

Additional tick-borne infections have been transmitted through blood transfusions, although less frequently:

• Anaplasma phagocytophilum (most common after Babesia)
• Tick-borne encephalitis viruses (including Powassan virus)
• Colorado tick fever virus
• Rickettsia rickettsii
• Ehrlichia ewingii

Emerging pathogens such as Borrelia miyamotoi are also increasing in incidence, raising additional concerns.

[bctt tweet=”Tick-borne infections can enter the blood supply—Babesia remains the leading risk.” username=”DrDanielCameron”]

What About Lyme Disease?

Borrelia burgdorferi, the bacterium responsible for Lyme disease, behaves differently.

It typically exists in low concentrations in the bloodstream, reducing the likelihood of transmission through blood transfusion.

Although the organism can survive in stored blood products, there have been no confirmed cases of Lyme disease transmitted through transfusion.

Clinical distinction: not all tick-borne infections carry the same transfusion risk.

Limits of Current Screening

Screening programs have successfully reduced transmission of infections such as HIV, hepatitis B, and malaria.

However, screening for tick-borne infections remains imperfect.

Studies have shown that donor questionnaires—such as asking about tick bites or prior illness—do not reliably identify infected individuals.

Key issue: asymptomatic infections and unreliable history limit current screening effectiveness.

Clinical Takeaway

Tick-borne infections pose a real but uneven risk to the blood supply, with Babesia representing the most significant threat.

As new pathogens emerge and incidence increases, improved screening strategies may be needed.

Key question: Are current blood safety measures enough to detect silent tick-borne infections?

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

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