Babesia Undertesting in Lyme Disease: A Hidden Gap in Diagnosis
Babesia undertesting remains a significant gap in tick-borne disease management. A large study examining nearly 3 million specimens found that only 3% included testing for Babesia—despite evidence that many Lyme disease patients may also be co-infected. :contentReference[oaicite:0]{index=0}
Babesia Undertesting: The Numbers
Data from seven large commercial laboratories showed that out of 2,978,881 specimens tested for tick-borne diseases, only 85,323 included Babesia testing.
In comparison, Lyme disease testing accounted for 2,432,396 orders.
This means Lyme tests were ordered nearly 30 times more often than Babesia tests, despite reported co-infection rates.
How Common Is Babesia in Lyme Patients?
A study in Vector-Borne and Zoonotic Diseases found that 28.6% of individuals with Lyme disease tested positive for Babesia microti.
Other studies report co-infection rates ranging from 10% to 32%, with some estimates approaching 40%.
These findings suggest Babesia co-infection may be more common than testing patterns reflect.
Why Babesia Undertesting Matters
Babesia requires a different treatment approach than Lyme disease.
Doxycycline, commonly used for Lyme disease, does not treat Babesia. Instead, treatment typically includes atovaquone combined with azithromycin.
When Babesia is not identified, patients may receive appropriate Lyme treatment but continue to experience symptoms such as fatigue, night sweats, or air hunger.
In these cases, persistent symptoms may reflect untreated co-infection rather than treatment failure alone.
Children and Diagnostic Challenges
The Curcio study found higher rates of Babesia infection in children ages 1 to 10.
Diagnosis in children can be challenging. Symptoms may overlap with common childhood illnesses, and children may not clearly describe features such as air hunger or night sweats.
Without targeted testing, Babesia may be overlooked.
Blood Supply Considerations
Babesia also has implications for blood safety.
B. microti is the most commonly reported transfusion-transmitted pathogen in the United States without universal donor screening.
Transfusion-transmitted babesiosis has been associated with serious complications and reported fatalities.
These findings highlight the broader public health relevance of Babesia detection.
When to Consider Babesia Testing
Babesia testing may be considered in patients with:
- Confirmed or suspected Lyme disease
- Persistent symptoms after Lyme treatment
- Unexplained anemia or low platelets
- Night sweats, air hunger, or cyclical fevers
PCR and antibody testing are available, though results may vary depending on timing and disease stage.
Clinical Perspective
Babesia undertesting represents a gap between observed co-infection rates and current testing practices.
Recognizing co-infection patterns may help explain persistent symptoms and guide more targeted evaluation.
Patients may benefit from understanding coinfections, reviewing testing limitations, and considering Babesia when symptoms do not fully resolve.
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
