Can Blood Smears Diagnose Borrelia miyamotoi Disease?
Blood smears may miss Borrelia infections
Thick and thin smears have important limitations
PCR testing may improve diagnostic accuracy
Some doctors have suggested that blood smears should be used to confirm the diagnosis of Borrelia miyamotoi disease (BMD). But as Telford and colleagues demonstrated, blood smears may not be reliable for diagnosing this tick-borne infection.
Patients often ask whether blood smears can identify Borrelia infections because some Borrelia species circulate in blood during infection. However, studies suggest blood smear sensitivity may be limited for detecting Borrelia miyamotoi.
In an effort to determine whether blood smears can detect B. miyamotoi in the blood of acute BMD patients, researchers examined sera from 20 patients who were positive for BMD by PCR testing.
The authors looked for evidence of BMD using standard malariological thick smears from anticoagulated blood samples.
After examining 100 thick smear fields in samples from 20 patients, investigators could not identify evidence of BMD in any patient.
Researchers eventually identified evidence of BMD in only 2 of 20 samples after examining 300 thick smear fields.
The authors concluded that microscopy of blood smears was not sensitive enough for confirming a diagnosis of BMD.
Thick Smear vs Thin Smear: Why It Matters
Thick and thin smears are commonly used to evaluate infections circulating in blood. Thick smears increase sensitivity by concentrating organisms, while thin smears improve visualization of morphology.
Even with thick smear techniques, researchers found poor sensitivity for diagnosing Borrelia miyamotoi disease.
Why Questions About Lyme Disease and Blood Smears Persist
Questions about blood smears and Lyme disease are not new. Historically, clinicians and researchers have debated whether Borrelia organisms circulating in blood during periods of spirochetemia could be visualized using microscopy.
However, this study evaluated Borrelia miyamotoi, not Lyme disease. Because Borrelia miyamotoi can circulate in blood differently than Borrelia burgdorferi, the findings should not automatically be generalized across all Borrelia infections.
Still, the study highlights an important diagnostic principle: blood smear sensitivity may be limited even when organisms are expected to circulate in blood.
This limitation may help explain why microscopy has largely been replaced by molecular and antibody-based testing strategies for many Borrelia infections.
The Centers for Disease Control and Prevention (CDC) continues to recommend PCR and antibody-based testing approaches for confirming Borrelia miyamotoi disease.
Editor’s note: The sensitivity of currently available PCR and antibody tests for BMD remains an area of ongoing discussion.
Frequently Asked Questions
Can Lyme disease be diagnosed with a blood smear?
Thick blood smears are best known for detecting blood-borne infections such as malaria and Babesia, where organisms may circulate in higher numbers in the bloodstream. Researchers have also explored blood smears in relapsing fever Borrelia infections such as Borrelia miyamotoi, which may circulate in blood more readily than Borrelia burgdorferi.
Classic Lyme disease caused by Borrelia burgdorferi is different. The organism is generally present in low numbers in blood, limiting the usefulness of blood smears for diagnosis. This study evaluated Borrelia miyamotoi, not Lyme disease, so its findings should not automatically be generalized across all Borrelia infections.
Still, questions remain regarding whether limitations observed with blood-based detection methods in Lyme disease may also apply to other Borrelia infections.
Can Borrelia miyamotoi be detected with a blood smear?
Studies suggest blood smears have poor sensitivity and may miss many cases.
What is the difference between thick and thin smears?
Thick smears increase detection sensitivity while thin smears improve visualization of organisms.
Is PCR better than blood smear testing?
PCR testing may improve detection because it identifies microbial genetic material rather than relying on visual detection.
Why are blood smears still used?
Blood smears remain useful for infections with higher organism levels in blood, including some parasitic diseases.
Clinical Takeaway
Blood smear testing appears to have poor sensitivity for diagnosing Borrelia miyamotoi disease.
Understanding the limitations of blood smear testing may help prevent missed diagnoses and support more appropriate test selection.
Related Articles
These related articles explore diagnostic challenges, emerging infections, and testing limitations involving tick-borne diseases.
Borrelia miyamotoi detected in Canada
Doctors face challenges diagnosing Borrelia miyamotoi
The best antibiotics to treat Borrelia miyamotoi?
Lyme disease misdiagnosis
Lyme disease testing
References
- Telford SR III, Goethert HK, Molloy PJ, Berardi V. Blood smears have poor sensitivity for confirming Borrelia miyamotoi disease. J Clin Microbiol. 2019.
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
Did they wait for how many hours, rechecking the findings hourly?
Those kind of spirochaetes bore themselves easily into the red blood cells as well as white blood cells. They dive to other tissues as well, particularly to bloodless ones. Like intervertebral discs, other joints, ligaments and tendons. It may take anything from 2-12 hours to see these bacteria coming out of those cells. That is when they can be seen moving in the plasma.
I summarized the frustration by the authors when testing for Borrelia miyamotoi. Hopefully your suggestion or others will lead to better tests.
Has anyone had testing for Lyme disease through urine . Ceres Urine Antigen?
My husband has been blood tested for Lyme, nope doesn’t have it. What he does have is severe abdominal pain that radiates and spends his life with the need to have a bowel movement. He is now on 2 Morphine’s , that do nothing really for the intense undiagnosed pain! He had to retire 3 years ago because he’s so ill. My son found this blog and the urine testing.
After spending all day in ER and once again checking with CT scans and bloodwork, pancreas, liver, gallbladder etc , all perfect, we need to find his problem. I think it’s Lyme disease. He’s was an avid bow hunter, always in the woods or outdoors, a tick magnet too. Walk out the door and BAM! He didn’t have to be in the woods or grass , just outside. Had the series of 3 vaccines to prevent Lyme disease when it came out in the 90’s. We live in VA, now deemed high in tick and Lyme’s.
Any help as to where to start?
I have not used the urine tests. I can not evaluate their reliability.
To Joyce Mahon – Both my husband and myself became ill with what was first diagnosed as Lymes disease. However my husband deteriorated rapidly until he put in the hospital with “diagnosis unknown”. He also most died before an excellent Infectious disease MD did blood slides and other test and discovered he had both Babesiosis & Ehrlichiosis and he was finally treated effectively, literally saving his life. Several years later I became very sick with high fevers and joint pain all over my body. I was taken to the hospital and admitted as a “toxic” patient as they could not diagnosis what I had. It was definitely not Lymes disease. Again it was finally diagnosed by an infectious disease MD as Borrelia Miyamotoi and treated appropriately and recovered. Again I am sick and the ER only checks for Lymes and tells me there is nothing wrong. So I now have an appointment with a top infectious disease specialist this week hoping it will be diagnosed properly. Please know that most ERs and physicians do not not test for these diseases and you must find a specialist who will. I urge you to do so as these diseases can leave lasting damage and potentially can be fatal.
I live on a dirt road surrounded by woods in NJ with lots of deer and other wildlife and there is little I can do about the ticks even though I use tick spray on myself and have my property sprayed several times each year. Good luck and best wishes. .
Where were you able to get blood slides. I am sure I have tick borne disease and I am near death.