Babesia duncani emerges in Eastern U.S. and may go undetected

The tick-borne illness Babesia duncani (B. duncani) was initially identified in the western regions of the United States. The disease has always been presumed to be confined to the West Coast, while its counterpart – Babesia microti (B. microti) has been well established on the East Coast.

New research indicates, however, there may no longer be a division of babesial strains between the East Coast and the West Coast. In their article “Babesia microtiBorrelia burgdorferi Co-infection,” Parveen reports that B. duncani has now been identified in eastern USA and Canada.¹

“Since B. duncani is widespread in Canada, its southern spread into northeastern U.S., an area already endemic for Lyme disease, makes co-infections with B. duncani and B. burgdorferi [Lyme disease] a possibility that needs to be carefully investigated.”

“While this review focuses on co-infection with B. microti and B. burgdorferi, there is some evidence that co-infections with a different Babesia species, B. duncani, and B. burgdorferi may be more common than previously suspected,” writes Parveen.

[bctt tweet=”Babesia duncani emerges as a threat on the East Coast and in Canada. ” username=”DrDanielCameron”]

The authors raise concerns regarding treatment given that, “Antibiotics used against B. microti are less effective against B. duncani, making treatment of B. duncani potentially more challenging.”

“Clinical cases caused by Babesia duncani have been associated with high parasite burden, severe pathology, and death,” writes Abraham in The Journal of Biological Chemistry²

Animals fared worse. “In both mice and hamsters, the parasite causes uncontrolled fulminant infections, which ultimately lead to death,” writes Abraham.

Treatment for B. microti was not as effective for B. duncani in vitro culture, explains Abraham.

“Using this in vitro culture assay, we found that B. duncani has low susceptibility to the four drugs recommended for treatment of human babesiosis, atovaquone, azithromycin, clindamycin, and quinine.”

“These data suggest that current practices are of limited effect in treating the disease [B. duncani],” writes Abraham.

Editor’s note: I have diagnostic concerns. B. duncani is not routinely tested for in Canada and the Eastern USA. Individuals with B. duncani may go undiagnosed.

  1. Parveen N, Bhanot P. Babesia microti-Borrelia Burgdorferi Coinfection. Pathogens. 2019 Jul 31;8(3). pii: E117. doi: 10.3390/pathogens8030117. Review.
  2. Abraham A, Brasov I, Thekkiniath J, Kilian N, Lawres L, Gao R, DeBus K, He L, Yu X, Zhu G, Graham MM, Liu X, Molestina R, Ben Mamoun C. Establishment of a continuous in vitro culture of Babesia duncani in human erythrocytes reveals unusually high tolerance to recommended therapies. J Biol Chem. 2018 Dec 28;293(52):19974-19981.

26 Replies to "Babesia duncani emerges in Eastern U.S. and may go undetected"

  • NoMoreWoodsyWoods
    01/29/2024 (1:47 pm)

    I am from NH. My test just came back positive for Babesia duncarni (more recent infection), Anaplasmosis (more recent infection), Bartonella Henselae (old infection), and Borrelia Burgdorferi (old infection). This was my first time having a Lyme test because of all of the strange and frustrating symptoms I have been dealing with. It is concerning to know that my system is dealing with all of these infections at once. We are treating the Babesia first with Atovaquone and azithromycin for 10 days, and then we are going to switch to herbal approach, possible UV blood treatment, and also tackle the other infections. I am wondering if the other infections make it more difficult to find complete resolution of Babesia and vice versa. Thoughts/experiences?

  • Stewart
    02/09/2023 (2:39 pm)

    I tested positive (IgG, Igenex) for B. duncani in 2007 two years after treatment with Mepron. I tested negative (IgG/IgM, Igenex) in 2005 for B. microti but my Lyme doctor treated me anyway. Mepron apparently worked for me; isn’t it the same as Atovaquone?

    A blood smear by Lida Mattman’s lab in 2000 showed Babesiosis in my blood cells using elecron microscopy, which doesn’t distinguish between species. I am from Maryland and had been to California one time… in 1985 while serving in the Navy. I attended SERE school in the mountains of SoCal for 1-2 weeks. My babesiosis in 2000 was presumed to be microti; I’d contracted Lyme in 1991 and initially I assumed coinfection at that time with microti. I didn’t get positive Lyme results until 2000 and had successful treatment for both by 2005 but didn’t realize it was duncani until 2007.

  • Joseph Hein
    07/10/2022 (3:53 pm)

    Dx with B. Duncani, Bartonella, and Lyme. It’s been over a year with no relief from Chronic Fatigue, Peripheral Neuropathy and Anemia. Been on Zithromax, Mepron, Mamaroneck for 8 weeks and Bactrim for 3 weeks. No improvement, only getting worse. See Hematologist next week.

  • Kathleen
    03/04/2022 (8:43 pm)

    My husband pulled a tick off of him in October. 2 weeks later he scheduled an appt. with his PCP to get a Lyme test. His doctor took a look at him and sent him to the ER, where he was admitted as an inpatient for five days due to the fact he was in liver failure. The second day of his hospital visit I asked the team to test him for babesiosis. After 10 hours of advocating for this test and telling them the test needed to be sent to a speciality lab, the did test him, but in their own lab. His test came back negative.

    We have been going through four months of pure hell with his team of doctors dismissing the idea of him having babesiosis, so I purchased a kit from It came back positive for babesia duncani on Feb 23rd. We were finally validated and he was referred to an infectious disease specialist who did not see the specialty lab results, only the initial negative ones, and told us he was sure my husband did not have babesiosis. When he finally received a copy of the positive lab results, he was surprised and wanted to know how my husband “picked up a West coast parasite”. After telling him we did not travel to the west coast and that he was bitten by a tick in our back yard in New Hampshire, he finally prescribed us with the treatment for babesiosis, but STILL thinks the liver failure and the babesiosis are not related.

    This has been beyond frustrating and it feels like we are fighting for his life daily and no one will treat this seriously.

    I’m just here to share this story and see if anyone else in the NH area has experienced something like this. According to what I have read babesia duncani has been on the East coast since approx. 2018. How are doctors here not up to date on babesiosis??

    • Rosanne
      03/24/2023 (9:40 pm)

      Kathleen, sorry to hear what you have been up against. I believe that the 2 times I got bit it was on the East coast (I live in CT). I tested positive for both duncani and microti. Seems only LLMD’s like Dr. Cameron are up to date and knowledgeable of this. Sadly, I know not everyone can afford to pay up front (then submit to insurance risking it won’t be covered). But I believe there is a big difference in the treatment you will get from someone Lyme Literate.

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