Positive Babesia Test But No Treatment: What Happens If Babesia Is Left Untreated?
Positive Babesia tests do not always lead to immediate treatment
Symptoms and coinfections can complicate management decisions
Delayed treatment may increase clinical uncertainty
In his article, Wormser discusses the case of a 61-year-old woman who went untreated for a Babesia infection despite positive test results. The patient, who lived in Westchester County, New York, a highly endemic area for Lyme disease, reportedly removed an unidentified tick from her left wrist at the end of March 2020, wrote Wormser.
This article discusses human Babesia infection rather than canine babesiosis.
A positive Babesia test without treatment creates difficult clinical questions. Does the infection require therapy? Could symptoms reflect Babesia alone, Lyme disease coinfection, or another tick-borne illness? In endemic regions, clinicians must also consider diagnostic uncertainty, overlapping coinfections, and the patient’s overall clinical presentation before deciding whether treatment is warranted.
In June, she developed intermittent fevers, joint pain, anorexia, and fatigue and was evaluated at the Lyme Disease Diagnostic Center (LDDC) in New York State.
Babesia Symptoms Without a Lyme Disease Rash
The patient did not develop an erythema migrans rash, which would have provided objective clinical evidence supporting a concurrent diagnosis of Lyme disease. No treatment for a tick-borne infection was started during her initial evaluation.
On July 30, 2020, the woman tested positive by PCR for Babesia but was not treated. Because PCR detects Babesia microti DNA circulating in the bloodstream, a positive result generally supports active infection rather than prior exposure.
Two weeks later, she had a positive Lyme enzyme immunoassay (EIA), but her Western blot did not yet meet CDC criteria for Lyme disease. Nevertheless, she was still not treated for either Lyme disease or Babesia.
On August 26, 2020, her Lyme EIA and IgM Western blot were reported as positive. However, because her symptoms had been present for more than 30 days, the clinical significance of an isolated IgM result was uncertain. CDC guidance advises disregarding positive IgM results obtained more than 30 days after symptom onset. Wormser interpreted the Lyme serology as a false-positive result associated with active babesiosis.
On December 11, 2020, the woman’s PCR test for Babesia and IgM Western blot test for Lyme disease were negative. Her Lyme EIA remained positive.
Untreated Babesia infection may raise concerns about persistent symptoms, ongoing parasitemia, relapse in selected patients, or unrecognized coinfections, particularly in endemic regions.
Delayed recognition of tick-borne illnesses may complicate interpretation of symptoms, particularly when clinicians are balancing multiple diagnostic possibilities. Learn more about delayed Lyme disease diagnosis.
Babesia Coinfection Concerns
Ixodes scapularis ticks infected with Babesia microti may also be coinfected with Borrelia burgdorferi, increasing the possibility of simultaneous tick-borne infections following a single tick bite.
The woman never developed more than two IgM Western blot bands for Lyme disease, and she never exhibited an erythema migrans rash. Had she developed an erythema migrans lesion, Dr. Wormser could have diagnosed Lyme disease clinically despite the diagnostic uncertainty created by Babesia.
As he states, “Diagnosing Lyme disease coinfection in patients with active babesiosis, as in patients with human granulocytic anaplasmosis, is more convincingly accomplished if objective clinical features of Lyme disease are present, such as an erythema migrans skin lesion.”
The relationship between Babesia and Lyme disease coinfection remains clinically important because overlapping symptoms may complicate diagnosis and treatment decisions. Learn more about Babesia and Lyme disease coinfection.
The woman’s fever resolved without treatment. However, Dr. Wormser did not report whether her joint pain, anorexia, or fatigue resolved. Nor did he describe whether she experienced any long-term consequences from the untreated tick-borne infection.
Can Untreated Babesia Cause Long-Term Problems?
Some immunocompetent patients with mild babesiosis may improve without treatment. However, infection may persist in selected individuals. Potential concerns include ongoing parasitemia, prolonged symptoms, and relapse, particularly in people with impaired immune function. Clinicians must also consider whether another tick-borne infection could be contributing to unresolved symptoms.
Clinical Perspective
I would have been uncomfortable leaving this patient untreated because she had compatible symptoms together with a positive Babesia PCR. Although treatment decisions should always be individualized, I would have been concerned about active Babesia infection and would also have evaluated the possibility of Lyme disease or another tick-borne coinfection.
The case raises important questions about how clinicians interpret positive Babesia PCR testing, persistent symptoms, and potentially misleading Lyme serology in endemic regions.
Frequently Asked Questions
Does a positive Babesia PCR always require treatment?
Not every positive Babesia PCR automatically requires treatment. People without symptoms may not require therapy. However, a positive PCR in a patient with compatible symptoms generally supports active babesiosis and warrants careful evaluation for treatment based on illness severity, immune status, age, and other clinical factors.
Can Babesia occur without Lyme disease?
Yes. Babesia can occur independently, although coinfection with Lyme disease is well recognized because both infections can be transmitted by Ixodes ticks.
Can Babesia symptoms resolve without treatment?
Some immunocompetent patients with mild babesiosis may improve without treatment. However, Babesia infection may persist in selected patients, and relapse or severe illness can occur, particularly among people who are older, immunocompromised, or without a functioning spleen.
What symptoms may occur with untreated Babesia infection?
Symptoms may include fatigue, fever, drenching sweats, weakness, joint pain, exercise intolerance, and loss of appetite, although clinical presentations vary considerably between individuals.
Why does Babesia coinfection make diagnosis harder?
Coinfections may create overlapping symptom patterns, complicate interpretation of laboratory testing, and make it more difficult to determine which infection is contributing most to a patient’s illness.
Clinical Takeaway
Positive Babesia testing without treatment creates uncertainty for both clinicians and patients.
When Babesia testing is positive, clinicians should carefully evaluate symptoms, immune status, possible coinfections, and the potential risks of delaying treatment before deciding on management.
Related Articles
These articles provide additional information on Babesia symptoms, persistent illness, and related diagnostic challenges.
Babesia: Symptoms, Diagnosis, and Treatment
Babesia symptoms
Post-treatment Lyme disease syndrome
Persistent Lyme disease
References
- Wormser GP. Documentation of a false positive Lyme disease serologic test in a patient with untreated Babesia microti infection carries implications for accurately determining the frequency of Lyme disease coinfections. Diagn Microbiol Infect Dis. 2021;101(1):115429.
- Waked R, Krause PJ. Human Babesiosis. Infect Dis Clin North Am. 2022;36(2):355-372.
- Krause PJ, Auwaerter PG, Bannuru RR, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA): 2020 Guideline on Diagnosis and Management of Babesiosis. Clin Infect Dis. 2021;72(2):e49-e64.
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
Thankfully my family doctor saw positive based on clinical observations, for Lyme and started me on antibiotics before the blood work came back proving that. It was caught and treated early, and I’ve been in remission since late 2012. Get rid of the bands, and the rash method and detect by CLINICALLY ASKING about and LISTENING TO PATIENTS symptons. Catch it sooner and treat aggressively!! I would not be alive today by the methods discussed in this article.
Unbelievable. Babesia (with Lyme, mycoplasma & toxoplasma) was responsible for my continued decline even though I received treatment for Lyme within 72 hours of exposure. It culminated in encephalitis, cognitive decline & constant fevers. Some symptoms resolved with IV antibiotics but UNTIL BABESIA WAS TREATED 2 YEARS LATER, I didn’t significantly improve. Now, 11 years later I still require oral Lyme & Babesia meds.
I have identical Lyme Carditis, I had a positive test but was never treated properly. I am left to die. 24 years of suffering and treated twice. Last time put on anibiotics I was resistant too. I had Babiesia diagnosis but I didn’t have Lyme Carditis symptoms until after improperly treated. Now I am dying. How do we get help.
I am sorry to hear you are still sick. Your story highlights how difficult it can be to be sure there is not an unresolved tick borne infection. I face this all the time in my practice. I also lean on other specialists to make sure there is not an underlying illness.
I was infected with Lyme Disease here in Asheville North Carolina a year ago. Fortunately, I had the rash behind my knee. I was treated and refused the short course of 10 days of doxycycline. I then saw an infectious disease doctor and was given a month of doxycycline. When I realized I had a nymph tick on the back of my knee I removed it and accidently dropped it on a patterned carpet. I vacuumed and remained concerned that it was in the apartment. My strictly indoor cat became ill and with great difficulty I got my vet to test him for Lyme. His test as she put it was only ‘mildly positive”. I then had difficulty getting him treated. I lived in Connecticut for years and Lyme was epidemic. I didn’t want to see him suffer from Lyme in his declining years. I don’t think people think of the fact that their dog can bring in an infected tick. The county health dept called to interview me regarding my case of Lyme. The nurse after hearing my story said “Oh yes, we had a diagnosis of Lyme and we treated the whole family and the dog.” I had Babiosis in Connecticut and was quite ill but didn’t have a diagnosis until a blood smear was taken through a Health Food Store. My question is does the Babesiosis remain in your body like Lyme?
I have patients who are failing other treatment until they add treatment for Babesia.
Why are doctors not treating this as a life threatening illness. I was just hospitalized for 5 days due to Babesia. I’ve never been so I’ll. For 3 days I was sleeping , fever, feeling paranoid, nightmares, nausea, headache, loss of balance, walking was affected, headache, loss of fine motor skills, my speech was declining like I was intoxicated. Finally went to the E.R. and had antibiotic I.V.and 5 other antibiotics. I am now having weekly blood tests and my platelets are being monitored ( total of 5 tests). If I had waited another couple days I would not be here. I thank my University of Penn professionals in Chester County, Pa.for getting me through this.
My mom has been extremely sick since 6 August. She developed the red rash on her arm the morning she went to urgent care (9 Aug) and was notified on 12 Aug that she tested positive for Lyme. The doctor, thankfully, was proactive and started her on doxycycline at the visit on the 9th. However, she continues to be very sick. After her second visit to the ER, we asked for testing for bartonella and Babesia, which both came back negative today. She has a headache (temples and eyes), extreme fatigue, body tremors, nausea, extreme loss of appetite with a weight loss of 16 pounds in the last 10 days, a chronic dry cough, shortness of breath upon exertion, gastrointestinal problems, short-term memory loss, and a CT shows she has some fluid around her heart. She sees her cardiologist tomorrow. My questions are, could she have those co-infections despite the tests being negative? Is it possibly the lyme bacteria has caused carditis which would be the reason for the cough? The doctor who tested for babesia and bartonella put her on a long and high tapered dose of prednisone (50 mg X 3 days, 40 mg X 3 days etc, down to 5 mg X 3 days) for the cough which seemed to make her get worse rather quickly. He agreed she could stop when it didn’t stop the cough after 4 days. We are at a loss and her PCM refuses to refer her anywhere for the lyme. We requested a referral to infectious disease at WVU Medical in Morgantown, WV but again, her said no. Any resources anyone can recommend so we can get mom the help she needs?
I have worked with patients who remain ill despite standard therapy for a tick borne illness. The tests for co-infections have not been as good as I would like. My patients also see other doctors to rule out other diseases including pulmonary and cardiac disease. Keep working on all fronts until she gets better.
I was exposed to mold at work for 8 years, diagnosed initially with Lyme through Igenex and clinically diagnosed with Babesia and Bartonella. Before being diagnosed with mold I had treated the lyme and co. For almost 2 years and many symptoms resolved but I had still persistent slurred speech and off balance and loss of fine motor skills that led to the testing for mold.
Although I treated with binders for over a year I didn’t have any resolution to these symptoms and then got Covid. All of my balance, slurred speech and motor skills have been exasperated and some new ones added. Could these symptoms be from babesia or from mold still although out of that exposure since I was diagnosed 12/4/20
I have had success with treating Lyme diseases and Babesia again. Others have reported success with mold treatment.