Babesia and Lyme — it’s worse than you think

Babesia and Lyme — it’s worse than you think

Babesia, a tick-borne infection that causes malaria-like symptoms, has been making headlines over the past two years as the number of reported cases increases, and concerns grow over the seriousness of the disease and its ability to be transmitted through the blood supply.

Although Lyme disease is the most talked about tick-transmitted disease, Babesia is more common than you might think. 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. [1]

This means that out of the estimated 300,000 cases of Lyme disease reported annually in the U.S., 120,000 of those individuals may also have Babesia. This is particularly alarming given that the disease can go undetected in asymptomatic individuals and is transmissible through blood transfusions or congenitally. Additionally, Babesia requires different treatment than Lyme disease.

The Babesia microti (B. microti) parasite that leads to Babesia is commonly seen in blacklegged deer ticks. But according to the authors, it’s also common to find ticks and enzootic hosts carrying both Borrelia burgdorferi (the causative agent of Lyme disease) and B. microti. In fact, between 12% and 42% of rodents are co-infected with both agents. This would suggest that “coinfection provides a survival advantage for both pathogens.” [1]


Source: CDC. Number of Babesiosis cases since it become a nationally reportable disease in 2011.

The first case of Babesiosis caused by the B. microti parasite was identified in 1969 in an individual who had vacationed in Massachusetts. It wasn’t until 2011, that it became a nationally notifiable disease with more than 1100 cases reported by the Centers for Disease Control and Prevention (CDC). Two years later, this number had risen to nearly 1800.

Setty and colleagues summarized their concern in a 2003 review, “Parasitemia in humans is transient and episodic. For this reason, there is a risk of asymptomatic donors transmitting the disease to recipients.” The authors raised concerns that there were 20 cases of Babesiosis and a variant Babesia strain called WA1 by red blood cells and blood component transfusions by 2003.

Babesia can lead to serious illness. Patients have presented with atrial fibrillation, [2] noncardiogenic pulmonary edema, [3] and anemia. [2] In New York, between 1982 and 1991, 7 people with Babesia died, while another patient on Nantucket Island developed pancarditis and died. [4]

Babesia occurs in individuals without the risk factors of increased age, prior splenectomy, immunosuppression, prematurity, and liver disease. [2] In one study of 192 patients, the average age was 46 years for individuals with Babesia. [5] The ages ranged from 27 to 83 years in a New York case series. [6] Five of 192 patients were immunosuppressed, [5] while none of the four subjects in another study had a splenectomy. [2]

Babesia can increase the severity of Lyme disease. Coinfected patients were more likely to have experienced fatigue, headache, sweats, chills, anorexia, emotional lability, nausea, conjunctivitis, and splenomegaly more frequently than those with Lyme disease alone. [7] 

Babesia can also increase the duration of illness with Lyme disease. Babesia patients can remain symptomatic for years with constitutional, musculoskeletal, or neurological symptoms. One study found that 50% of coinfected patients were symptomatic for 3 months or longer, compared to only 4% of patients who had Lyme disease alone. [7] Meanwhile, one-third of patients with a history of both Babesia and Lyme disease remained symptomatic an average of 6 years. [2]

“The clinical pictures for 3 out of our 4 coinfected patients included a large number of symptoms, and 1 coinfected patient had persistent fatigue after treatment,” according to a study by Steere and colleagues. [8] [bctt tweet=”Babesia and Lyme — it’s worse than you think” username=”DrDanielCameron”]

Babesia – difficult to diagnose 

Equally worrisome is the fact that the disease can be difficult to diagnose based on symptoms. Nearly all patients with Babesia reported sweats. However, if the patient was coinfected with Lyme disease, the incidence of sweats dropped to 42%. Sweats can also be reported in other tick borne illnesses. [5]

Blood sample for babesia parasite testingBabesia can also be difficult to diagnose with current testing. The parasite was detected microscopically in as few as one-third of patients with Babesia. [5] Specific amplifiable DNA and IgM antibody were more likely to be positive. [5] The reliability of tests for Babesia in actual practice remains to be determined.

The Babesia tests can become negative. The Babesia sporozoites can be too few in number to be detected on a thin smear or can resolve with or without treatment. It’s been reported that a positive serologic test for B. microti will decay over time, leading to a negative test. Half of the patients with positive serologic tests for B. microti were negative on follow-up. [2]

Treating Babesia  

Babesia cannot be treated with the same medications used to treat Lyme disease. Doxycycline is effective for Lyme disease, Ehrlichia, and Anaplasmosis but not for Babesia.   Treatment with Mepron and Zithromax has been effective for Babesia. Quinine and clindamycin have also been effective but are associated with a higher rate of side effects. Flagyl and Tindamax drugs have been proposed but not well studied. The optimal treatment for Babesia has yet to be worked out.

Physicians have different views over the diagnosis and treatment of Babesia. The Infectious Diseases Society of America’s (IDSA) guidelines advise:

  1. Symptomatic patients whose serum contains antibody to Babesia but whose blood lacks identifiable Babesia parasites on smear or Babesia DNA by PCR should not receive treatment.
  2. Treatment is also not recommended for asymptomatic individuals, regardless of the results of serologic examination, blood smears, or PCR.
  3. Asymptomatic patients with positive Babesial smears and/or PCR should have these studies repeated, and a course of treatment should be considered if Parasitemia persists for >3 months. [9]

There are physicians who have elected not to treat Babesia patients, who are asymptomatic. In 1998, Krause and colleagues reported, “24 of 46 Babesia-infected subjects, who received no specific treatment, had Babesia DNA detectable in their blood for an average of 82 days.” [10]

In 2002, Krause et al reported, “Because symptoms had resolved or improved by the time concurrent Babesiosis or HGE was diagnosed, therapy was not administered to 38 (58%) of the patients with Lyme disease plus Babesiosis.” [5]

There are physicians concerned that symptoms of Babesia may be overlooked when evaluating patients. [11] The symptoms of chronic Lyme disease were overlooked for up to 14 years until reported in the 1990 New England Journal of Medicine by Logigian et al. [12] Meanwhile, the symptoms of Lyme disease were dismissed in by the IDSA Lyme disease guideline committee in 2000 and 2006 as nothing more than the aches and pains of daily living. [11] And the severity of the chronic manifestations were not validated until the 4 National Institutes of Health (NIH) sponsored clinical trials were completed. [13]



  1. Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes Tick-Borne Pathogens: Ecological, Epidemiological, and Clinical Consequences. Trends Parasitol, (2015).
  2. Wang TJ, Liang MH, Sangha O et al. Coexposure to Borrelia burgdorferi and Babesia microti does not worsen the long-term outcome of lyme disease. Clin Infect Dis, 31(5), 1149-1154 (2000).
  3. Golightly LM, Hirschhorn LR, Weller PF. Fever and headache in a splenectomized woman. Rev Infect Dis, 11(4), 629-637 (1989).
  4. Marcus LC, Steere AC, Duray PH, Anderson AE, Mahoney EB. Fatal pancarditis in a patient with coexistent Lyme disease and babesiosis. Demonstration of spirochetes in the myocardium. Ann Intern Med, 103(3), 374-376 (1985).
  5. Krause PJ, McKay K, Thompson CA et al. Disease-specific diagnosis of coinfecting tickborne zoonoses: babesiosis, human granulocytic ehrlichiosis, and Lyme disease. Clin Infect Dis, 34(9), 1184-1191 (2002).
  6. Meldrum SC, Birkhead GS, White DJ, Benach JL, Morse DL. Human babesiosis in New York State: an epidemiological description of 136 cases. Clin Infect Dis, 15(6), 1019-1023 (1992).
  7. Krause PJ, Feder HM, Jr. Lyme disease and babesiosis. Adv Pediatr Infect Dis, 9, 183-209 (1994).
  8. Steere AC, McHugh G, Suarez C, Hoitt J, Damle N, Sikand VK. Prospective study of coinfection in patients with erythema migrans. Clin Infect Dis, 36(8), 1078-1081 (2003).
  9. Wormser GP, Dattwyler RJ, Shapiro ED et al. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis, 43(9), 1089-1134 (2006).
  10. Krause PJ, Spielman A, Telford SR, 3rd et al. Persistent parasitemia after acute babesiosis. N Engl J Med, 339(3), 160-165 (1998).
  11. Cameron DJ, Johnson LB, Maloney EL. Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease. Expert Rev Anti Infect Ther, 1-33 (2014).
  12. Logigian EL, Kaplan RF, Steere AC. Chronic neurologic manifestations of Lyme disease. N Engl J Med, 323(21), 1438-1444 (1990).
  13. Cameron DJ. Clinical trials validate the severity of persistent Lyme disease symptoms. Med Hypotheses, 72, 153-156 (2008).

372 Replies to "Babesia and Lyme — it’s worse than you think"

  • sandra
    03/31/2023 (7:53 pm)

    In your opinion which is more effective for treating Babesia; Mepron or Malerone?

    • Dr. Daniel Cameron
      04/01/2023 (7:12 am)

      I have used both. I tend to start with Malarone first as it is better tolerated, less costly, and is easily taken as a pill. Both offer atovaquone.

  • MzAdvenvtures
    01/07/2023 (2:52 pm)

    Just turned 55, and can trace the first Lyme, maybe more, infection back to three months before I turned 9. Well before it had the name we now know it by. Most likely, I was infected at birth, given the issues I had. It was all tossed under Woodsman’s Disease back then and you were taught not to let others know, never show pain or anything else.

    In the last four years I have been diagnosed with Lyme, Neuro Lyme, Babesia, Bartonella, CMV, Anaplasmosis, Hashimoto’s, severe diabetes symptoms, but those are a red herring, MCAS, CIRS/SIRS. Could not afford a full panel through IgeneX, so, the thought is there is more.

    Double bypass 4 years 4 months ago. After a year of complaining to deaf ears, convinced a cardiologist to do a stress echo, then he did another heart cath. His words when done, “F&**, you were right, their surgery didn’t work. The whole bottom part is closed. Nothing we can do, no stent, no surgeries, just hope to find a working med. You will be lucky to get 2 years.” Well, I am still alive, but have no quality of life. I haven’t been able to read a book i over 10 years. Just this little comment, wipes me out. My DO told me yesterday tha the hoped I had a signed DNR order on file everywhere and on my person. Gee thanks for the vote of confidence doc. I have 3 to 5 nitro patches on 24/7 and take up to 10 nitro tablets a day. And my BP will still shoot up to 231/140 hr 115….or similar. My average is 197/101 pulse preferably under 72 or I end up with heart attacks (spill troponin and all), chest pain, down the arms, into jaw and the brain. Fun times.

    I am wondering now if some of this isn’t Babesia related instead of Lyme?????

    Good thing I am stubborn. Oh, and disability is denied because my EKG barely shows a blip.

  • Casie
    12/27/2022 (1:32 pm)

    Hi Dr Cameron. First, thank you for the wonderful work you are doing. Your office has already been very helpful to me and I couldn’t be more grateful. I was bitten by at least 2 ticks in Slovenia in October. Based on the evidence I have (which isn’t perfect of course), it looks like one of the ticks was a sheep tick and had been attached for 1-2 days. I started doxy (100 mg, 2x a day) at apx the 48-hours-after mark. Then, after returning home, I saw a lyme specialist on the US west coast who recommended doubling that (200 mg, 2x a day) while waiting until enough time had passed to do more testing. She tested me for lyme and babesia using igenex. The lyme test shows 3 bands positive (weak, 1 +) and shows the strain as a U.S. strain. All the Babesia tests who negative except for the FISH test, which shows positive. She is suggesting 6 months of Malarone (as well as testing for additional infections). I have had no symptoms at all, except for 3-4 days after returning home from Slovenia, at which time I felt very tired and sort of mentally slow, but that could have been jet lag (though it was worse than any jet leg I’d ever experienced). If I didn’t know anything of this was happening, I wouldn’t think anything was going on with me physically. I run 5-6 miles 3 times a week, lift weights, as I have been doing for years and am not noticing anything unusual.

    Having read that Babesia usually clears up on it’s own, I was already skeptical about taking 6 months of Malarone and then my pharmacy told me that the manufacturer of Malorone says it is out of stock. If you were me, would you do anything about the positive FISH babesia? And/or what would you recommend for a patient? If there is a likeliness that it will clear up on it’s own, I prefer to let that happen. I would want to avoid a situation where it flares up down the road too though. I was diagnosed with hashimotos 20 years ago, other than that, no health issues.

    Do you do second opinion appointments virtually?

    Again, thank you SO MUCH for what you are doing.

  • Eric
    10/19/2022 (12:08 pm)

    Diagnosed 3 weeks ago with Lyme, Babiosa and Covid 19 .
    Now have AFIB , hopefully will go away soon
    What a stretch for recovery.

    • Dr. Daniel Cameron
      10/19/2022 (12:32 pm)

      I assume you are also working with a cardiologist. Get well soon.

      • Sherry
        10/19/2022 (2:25 pm)

        Dr Cameron, if a Hematologist says he seen Babesia on a smear, is a positive PCR needed for confirmation? My Hematologist says he saw Babesia on 2 out of 3 smears, but will not treat because confirmatory PCR through Mayo was negative.

        • Dr. Daniel Cameron
          10/20/2022 (2:24 pm)

          The Babesia parasite clears without treatment. I have had some patients whose PCR and antibodies are negative yet do well with treatment for Babesia.

  • Melanie Driscoll
    10/12/2022 (1:24 am)

    Dr. Cameron, I did low dose disulfiram on and off for several months over the past year. Each time i have ended up with dizziness, nausea, headaches, and revelry with heart palpitations and extreme fatigue. My reaction to DSF is making me suspect that treatment with it might be stirring up Babesiosis. I’ve never had a positive test but have had Lyme for many years and also got a new tick bite about a year ago. I had the tick tested and it tested negative for Babesiosis. However, I have been declining in health even from my previous status for several months. Would taking Mepron or Malarone give me a treatment reaction that might indicate the presence of an infection with Babesia? Also, I am in peri menopause, so struggling to distinguish between those symptoms and unresolved tick borne illnesses.

    • Dr. Daniel Cameron
      10/12/2022 (10:31 am)

      I have patients in my practice who need to find Malarone/Mepron helps.

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