Babesia After Lyme Treatment: Why Symptoms Return Weeks Later (And Are Missed)
The Lyme rash appears.
Treatment begins—and symptoms improve.
Then new symptoms suddenly develop.
Babesia after Lyme treatment may explain why some patients relapse or develop new symptoms weeks after starting antibiotics.
This is one of the most common reasons patients relapse after Lyme disease treatment.
This is where one infection can overshadow another.
This case highlights how a delayed Babesia infection can complicate Lyme disease recovery. :contentReference[oaicite:0]{index=0}
This is part of a broader pattern of co-infections driving persistent symptoms in Lyme disease.
Start here: Lyme disease symptoms guide
Can Babesia Appear After Lyme Treatment?
Can a second infection appear weeks later?
Many assume tick-borne infections occur at the same time—but that is not always the case.
A 67-year-old woman developed Babesia infection nearly three weeks after being treated for Lyme disease.
This delay may explain why some patients relapse after initial improvement.
Delayed Babesia infection has been described in multiple clinical reports.
What Happened in This Case?
How did symptoms evolve?
The patient had a history of outdoor exposure and developed a rash consistent with erythema migrans.
She was treated with amoxicillin for three weeks.
Near the end of treatment, her condition worsened.
She developed:
- Fever up to 102.9°F
- Fatigue and weakness
- Muscle aches
- Dizziness
This is where symptoms no longer fit Lyme disease alone.
Why Was Babesia Missed Initially?
This is where diagnosis becomes challenging.
Her initial symptoms were consistent with Lyme disease, and treatment was started appropriately.
However, Babesia was not identified until symptoms worsened.
This reflects a broader pattern of Babesia undertesting in Lyme disease.
See: Babesia undertesting in Lyme disease
How Was Babesia Diagnosed?
What confirmed the diagnosis?
Testing revealed:
- Positive PCR for Babesia microti
- Parasites seen on blood smear
- 0.4% of red blood cells infected
Laboratory findings also included:
- Anemia
- Low platelet count
- Elevated inflammatory markers
This is where the diagnosis shifted from Lyme to co-infection.
Why Babesia Causes New Symptoms
Why did symptoms worsen during treatment?
Babesia is a parasite that infects red blood cells.
Lyme antibiotics such as amoxicillin do not treat Babesia.
This means the infection can progress even while Lyme disease is being treated.
This is where new symptoms may emerge despite appropriate therapy.
How Was the Patient Treated?
What treatment led to improvement?
The patient was treated with:
- Azithromycin
- Atovaquone
Her fever resolved within five days.
Her platelet count improved significantly during treatment.
However, fatigue persisted after treatment.
Why This Case Matters
What can we learn from this delayed Babesia infection?
Babesia may not appear at the same time as Lyme disease.
Symptoms can emerge weeks later, leading to confusion and delayed diagnosis.
This pattern may explain why some patients:
- Relapse after Lyme treatment
- Develop new symptoms
- Do not respond as expected
This is part of a broader pattern of co-infections complicating Lyme disease.
Clinical Takeaway
Babesia infection may develop or become apparent weeks after Lyme disease treatment.
It should be considered in patients who worsen or relapse after initial improvement.
If symptoms return after Lyme treatment, it’s worth asking whether a delayed Babesia infection has been missed.
Related Reading
References
- Hoversten, K., & Bartlett, M. A. (2018). Diagnosis of a tick-borne coinfection in a patient with persistent symptoms following treatment for Lyme disease. BMJ Case Reports.
- Saetre, K., Godhwani, N., Maria, M., et al. (2017). Congenital babesiosis after maternal infection with Borrelia burgdorferi and Babesia microti. Journal of the Pediatric Infectious Diseases Society.
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
I was just diagnosed with Lyme disease and I think I have had it for a long time. I had been bitten by a tick in early spring but my doctor was not worried and never ordered test. I became extremely ill. Fatigued, nauseous, just didn’t feel good. I soon started getting these spells where I would suddenly feel like I was going to pass out, then I would start dry heaving and then I would be okay. Then suddenly it would happen again. I went to emergency room with pain in my left arm left chest and jaw and they did a bunch of bloodwork. My potassium was down to 2.4 and they said that was the cause and gave me potassium. After some time I felt somewhat better and thought I would be ok. About 3 months later it all began again, my potassium was low again despite my being on supplements daily since the first time. After about two weeks I felt again somewhat better but not normal. Still suffering from fatigue and swelling in my leg so bad that at times I could barely walk. About a month ago I began having massive pain in my legs but it felt like it was deep. My leg muscles ached so bad that it’s hard to even stand up. I went to get my knee checked out but my other leg had swollen to about three times it’s normal size and the pain in my muscles and joints was beyond anything I have ever felt. The doctor ordered a test for Lyme disease and it was positive. I am now on doxycycline and it’s been a week with no changes in swelling or symptoms. How long before I start feeling better? The pain is debilitating, the swelling is still massive dispute taking ibuprofen and Tylenol and I am not able to take anything else for the pain because I have had a previous issue with opiates and have been in recovery for years and doing great. I already suffer with chronic depression and this doesn’t help. The pain is so bad and I don’t know what to do at this point I’ve been sick for months with short spirts of feeling okay. Please help me to understand what could be happening
I have Lyme disease patients with similar stories. I don’t typically see much change after a week of doxycycline if one had been ill for a long time. I have seen Lyme disease increase pain even from old injuries. I also advise my patients to work with other specialists to rule out other causes of illness.