A Babesia infection 3 weeks after treatment for Lyme disease.

I will discuss a 67-year-old woman with a Babesia infection 3 weeks after treatment for Lyme disease. Could this delay explain why some patients remain ill or relapse?


Hoversten and her colleague first discussed this case in the British Medical Journal Case Reports  in 2018.

One would expect that tick-borne infections would all occur at the same time.

One would be wrong, as this case illustrates.

A 67-year-old woman from Wisconsin had extensive exposure as an avid gardener and spent a considerable amount of time outdoors.

She did not see a tick. She did see a rash consistent with an erythema migrans rash.

A delay in onset of Babesia may explain why some Lyme disease patients relapse after initially improving with doxycycline or amoxicillin. CLICK TO TWEET

She was prescribed amoxicillin for three-weeks as she was allergic to doxycycline.

Near the end of three-week of amoxicillin, she became ill. Her fever rose to 102.9 F0. She complained of myalgias, dizziness, and fatigue.

Her blood test showed mild anemia, a low platelet count and neutrophil count, and a very high C-reactive protein.

  • neutrophil is a type of white blood cell that helps resolve infections and heal damaged tissues. A low neutrophil count can be seen in tick-borne diseases.
  • A high C-reactive protein is a marker for inflammation but cannot be used to determine what type of inflammation.

She was admitted to the hospital. The doctors thought she might be suffering from sepsis or a tick-borne infection.

  • Sepsis is a life-threatening illness caused by your body’s response to an infection.
  • Her red blood count and platelets continued to drop.
  • She was transferred to a second hospital.
  • There was no evidence of sepsis. The blood cultures were negative after five days.


She was diagnosed with the parasite Babesia microti by PCR and by a thin smear of her red blood cells. Typically, Babesia microti is seen on a thick smear of blood. In her case, 0.4% of her red blood cells showed the parasite Babesia microti on a thin smear.

Babesia infections can be severe and, in rare cases, life-threatening. Babesia infections can also be mild or without symptoms. Babesia was more likely to be severe in this woman as she was over 50-years of age and had a history of colon cancer.

She was prescribed a 10-day course of azithromycin and atovaquone. By 5th day of treatment, her fever had resolved, and her platelet count had more than doubled from a low of 17,000 per dl to 42, 000 per dl.

The authors report that the woman remains fatigued after completing treatment.

The authors discussed the nearly three-week gap in time between the woman’s erythema migrans rash and her diagnosis of Babesia. This is not the first case where the onset of Babesia was delayed.

The authors cited two papers describing a 3 to 4-week delay in the onset of Babesia. I described a paper in an earlier podcast where two babies contracted Babesia from their mothers. They did not present with Babesia until after being discharged from the hospital. You can read more about these babies in the article by Saetre and colleagues or listen to my Inside Lyme podcast titled. “Two children who contacted Babesia from their mother.”

This delay may explain why some Lyme disease patients relapse after initially improving with doxycycline or amoxicillin. Treatment for Lyme disease with doxycycline or amoxicillin is not effective for the treatment of Babesia.

What can we learn from this cases?

  1. Babesia infections can occur weeks after the onset of Lyme disease.

What questions does these cases raise?

  1. Should the woman have been evaluated for Babesia infection at the time of the erythema migrans?
  2. Would a Babesia infection have been recognized if the woman had not been diagnosed with Lyme disease?
  3. Should Lyme disease patients be advised to return for follow-up?
  4. Would earlier treatment have avoided the need for hospitalization?
  5. What is the long-term outcome for this woman with a Babesia infection


In my practice, each individual requires a careful assessment. That is why I order a broad range of blood tests for other illnesses in addition to tick-borne infections. I also arrange consultations with specialists as needed.

Many patients are complex, as highlighted in this Inside Lyme Podcast series.

We need more doctors with skills recognizing Babesia in a patient with Lyme disease. We hope that professionals evaluating individuals with Lyme disease can use this case to remind them to look for Babesia with Lyme disease.

Inside Lyme Podcast Series

This Inside Lyme case series will be discussed on my Facebook and made available on podcast and YouTube.  As always, it is your likes, comments, and shares that help spread the word about this series and our work. If you can, please leave a review on iTunes or wherever else you get your podcasts.

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