The Screening Gap in Tick-Borne Disease Management

Babesia undertesting is a significant problem in tick-borne disease management. A study examining nearly 3 million specimens found that only 3% involved testing for Babesia—yet research shows up to 30% of Lyme disease patients may be co-infected.

Babesia Undertesting: The Numbers

When data was collected from 7 large commercial laboratories, results indicated that out of nearly 3 million (2,978,881) specimens tested for tick-borne diseases, only 3% involved testing for Babesia.

The disparity is striking:

Lyme disease tests ordered: 2,432,396. Babesia tests ordered: 85,323.

This means doctors order Lyme tests nearly 30 times more often than Babesia tests—despite the high rate of co-infection.

30% of Lyme Patients Test Positive for Babesia

A study published in Vector-Borne and Zoonotic Diseases examined the seroprevalence of B. microti infection in individuals who tested positive for Lyme disease. The authors found that nearly 30% (28.6%) of serum samples taken from individuals with Lyme disease tested positive for Babesia.

The high prevalence is consistent with other research. “Co-infection rates of B. microti with B. burgdorferi in humans vary greatly and can range from 10% to 32%,” according to Curcio from the Department of Biomedical Sciences, Long Island University.

In the 2015 issue of Trends in Parasitology, Diuk-Wasser and colleagues report that up to 40% of patients with Lyme disease experienced concurrent Babesiosis.

Why Babesia Undertesting Matters

Identifying Babesia is critical since antibiotic treatment differs from that prescribed for Lyme disease.

“Doxycycline is the preferred oral treatment because it has activity against other tick-borne illnesses such as human granulocytic anaplasmosis, whereas the treatment for Babesiosis is a combination of atovaquone and azithromycin,” explains Curcio.

When patients have both infections but only get tested for Lyme, they may receive doxycycline alone—which won’t treat their Babesia. This leads to persistent symptoms and delayed recovery.

The clinical scenario is predictable: patient presents with tick bite or erythema migrans rash. Lyme disease is diagnosed. Doxycycline is prescribed. Patient takes full course of antibiotics. Initial symptoms improve slightly but fatigue, night sweats, and air hunger persist. Doctor concludes “treatment failed” or attributes ongoing symptoms to post-treatment Lyme disease syndrome. In reality, the Babesia co-infection was never identified or treated.

Children at Highest Risk

In the Curcio study, the highest incidence of Babesia occurred in children between 1 and 10 years old.

This is concerning because Babesia in young children can be difficult to diagnose. The symptoms overlap with many childhood illnesses, and doctors may not think to test for tick-borne co-infections.

Children may not report or recognize symptoms like air hunger or night sweats. Parents may attribute fatigue to growth phases or school stress. Cyclical fevers may be dismissed as recurrent viral infections.

Without specific Babesia testing, pediatric cases are easily missed—leaving children with untreated parasitic infection that can persist for months or years.

Blood Supply Concerns

Curcio and colleagues express concern over the transmission of Babesia through blood banks if patients are not evaluated for the disease.

“B. microti is the highest ranking pathogen that is transmitted by blood transfusion in the United States, for which there is no FDA-approved donor screen currently implemented.”

“Transfusion transmitted babesiosis (TTB) has high fatality in transfusion recipients with 28 deaths attributed to complications from TTB reported from 1979 to 2009,” she adds. “And 4 TTB-associated deaths reported to the FDA between 2010 and 2014.”

Babesia has already been reported in the blood supply. A study by Tonnetti and colleagues found that of the 2,150 donations tested in Minnesota, 42 donors (2.0%) were positive by IFA.

“It could be expected that the number of tested blood donors in New York State would be higher,” explains Curcio, “as it represents 37.2% of the total number of CDC-reported babesiosis cases.”

This public health dimension underscores why Babesia undertesting matters beyond individual patient care. Every missed diagnosis represents a potential asymptomatic blood donor who could transmit parasitemia to vulnerable transfusion recipients.

The Case for Universal Screening

The authors suggest babesiosis screening for the nearly 5 million recipients who undergo blood transfusions annually in the USA. “Thus, the implementation of an FDA-approved screening has the potential to save many lives.”

Beyond blood banks, clinicians should consider Babesia testing for any patient in an endemic area with:

Confirmed or suspected Lyme disease. Persistent symptoms despite Lyme treatment. Unexplained anemia or low platelets. Night sweats, air hunger, or cyclical fevers.

The testing is straightforward—PCR and antibody testing are readily available through commercial laboratories. The cost is modest compared to the clinical consequences of missed diagnosis. Yet only 3% of tick-borne disease specimens undergo Babesia evaluation.

Clinical Implications for Practice

The clinical presentation and outcome for patients positive for Babesia was not examined in this study. “We presumed that these individuals were symptomatic because they were being tested for Lyme disease; however, we have no clinical information regarding previous tick exposure or diagnoses,” according to Curcio.

This limitation highlights an important point: we don’t know how many of these co-infected patients received appropriate treatment. Were they treated only for Lyme disease? Did their symptoms persist? How many were eventually diagnosed with post-treatment Lyme disease syndrome when in fact they had untreated Babesia?

In clinical practice, routine co-infection testing addresses this gap. When Lyme disease is diagnosed, simultaneous Babesia testing identifies co-infection before treatment begins—allowing appropriate antimicrobial selection from the outset rather than discovering co-infection only after Lyme-directed therapy fails.

Frequently Asked Questions

Why is Babesia undertested?
Many doctors don’t think to order Babesia tests, especially outside known endemic areas. Out of nearly 3 million tick-borne disease tests, only 3% included Babesia screening. This reflects a knowledge gap about co-infection rates and the different treatment Babesia requires.

How common is Babesia in Lyme patients?
Studies show 10-40% of Lyme disease patients may have concurrent Babesia. The Curcio study found 28.6% of Lyme patients tested positive for Babesia antibodies. Diuk-Wasser reported up to 40% co-infection rates in some populations.

Why does it matter if Babesia is missed?
Lyme disease treatment (doxycycline, amoxicillin) doesn’t treat Babesia. Patients with both infections need additional medications—atovaquone plus azithromycin—to recover. Without Babesia treatment, symptoms persist despite adequate Lyme therapy.

Should all Lyme patients be tested for Babesia?
In endemic areas, yes. Especially if symptoms persist despite treatment, or if the patient has anemia, low platelets, night sweats, air hunger, or cyclical fevers. The high co-infection rate (up to 40%) justifies routine screening.

Is Babesia a risk for blood transfusions?
Yes. B. microti is the highest-ranking transfusion-transmitted pathogen in the US without FDA-approved donor screening. There have been at least 32 deaths from transfusion-transmitted babesiosis between 1979 and 2014.

Clinical Takeaway

Babesia undertesting represents a major gap in tick-borne disease management with serious clinical consequences. Analysis of nearly 3 million specimens from 7 large commercial laboratories revealed that only 3% involved Babesia testing—despite research showing 10-40% of Lyme disease patients have concurrent Babesia infection. The numbers are stark: 2,432,396 Lyme tests ordered versus 85,323 Babesia tests. Doctors order Lyme tests nearly 30 times more often than Babesia tests. The Curcio study found 28.6% of individuals with Lyme disease tested positive for Babesia antibodies. Other research reports co-infection rates ranging from 10-32%, with some studies showing up to 40% concurrent babesiosis in Lyme patients. This means thousands of patients are being tested for Lyme disease, diagnosed, and treated—while their Babesia co-infection goes completely unrecognized. The clinical implications are significant. Babesia requires different treatment than Lyme disease. Doxycycline, the preferred treatment for Lyme, has no activity against Babesia. Babesia requires atovaquone plus azithromycin. When patients have both infections but only receive doxycycline, the Lyme may improve but Babesia persists. Symptoms continue: crushing fatigue, night sweats, air hunger, cyclical fevers. Doctors attribute these to “treatment failure” or “post-treatment Lyme disease syndrome” when in fact untreated Babesia is the cause. Children face particular risk. The Curcio study found highest incidence in children ages 1-10. Babesia symptoms overlap with common childhood illnesses. Children may not report or recognize air hunger or night sweats. Without specific testing, pediatric Babesia is easily missed. Beyond individual patient care, Babesia undertesting has public health implications. B. microti is the highest-ranking transfusion-transmitted pathogen in the United States without FDA-approved donor screening. Between 1979 and 2014, at least 32 deaths were attributed to transfusion-transmitted babesiosis. A Minnesota study found 2% of blood donors tested positive for Babesia antibodies. Every missed diagnosis represents a potential asymptomatic donor who could transmit parasitemia to vulnerable transfusion recipients. The solution is straightforward: routine Babesia testing for patients diagnosed with Lyme disease, particularly in endemic areas. PCR and antibody testing are readily available through commercial laboratories. The cost is modest. Yet current practice patterns show this isn’t happening. Only 3% of tick-borne disease tests include Babesia screening—leaving the majority of co-infected patients undiagnosed and undertreated.