Babesia Infection Without a Spleen: Why Asplenia Can Lead to Prolonged Infection
Babesia infection may last longer after splenectomy
Asplenia can impair clearance of infected red blood cells
Extended treatment and follow-up may be necessary
Babesia infection without a spleen can be more severe and difficult to clear. The spleen helps remove Babesia-infected red blood cells and supports the immune response against the parasite. Without a functioning spleen, parasitemia may persist despite appropriate treatment.
In their study “Trust the Process: Prolonged Babesia Parasitemia in an Elderly Man with Asplenia from the American Midwest,” Ivancich and colleagues describe an 89-year-old man with multiple comorbidities and a prior splenectomy who required eight weeks of treatment before his Babesia infection cleared.1
Why can Babesia be more severe without a spleen?
Babesia parasites infect red blood cells. The spleen plays an important role in recognizing and removing these infected cells from circulation. Macrophages within the spleen also participate in the immune response that helps control parasitemia.
Patients who have undergone splenectomy or who have impaired splenic function are at greater risk for severe illness, persistent parasitemia, prolonged treatment, and relapse.
The authors explain that Babesia is controlled primarily by the innate immune system. Macrophages in the spleen remove infected red blood cells and help coordinate the immune response through inflammatory cytokines such as TNF and IL-12. Without a functioning spleen, infected cells are cleared less efficiently, allowing parasitemia to persist despite appropriate antimicrobial therapy.
An elderly patient develops weakness and fever
The man was evaluated after a fall at home. Before the fall, he reportedly had a fever for two to three days, loss of appetite, and generalized weakness for one week.
“The patient had thrombocytopenia, leukocytosis with neutrophilia, transaminitis, hyperbilirubinemia, and elevated creatine kinase level consistent with tick-borne illness,” wrote the authors.
The patient lived in rural Wisconsin near a wooded area and had two cats, one of whom lived outdoors. He did not recall a recent tick bite.
“We present a case of Babesia parasitemia lasting more than 6 weeks and requiring almost 8 weeks of parasite specific therapy in a patient with asplenia.”
The man was initially treated empirically with doxycycline and intravenous ceftriaxone for a suspected tick-borne infection.
Tests reveal Lyme disease and Babesia infection
The patient tested positive for Lyme disease by IgM and IgG immunoblot testing. He also tested positive for Babesia microti based on a blood smear, PCR testing, and a high-titer antibody test.
His initial peripheral blood smear showed a Babesia parasitemia level of 7.44%. Testing for ehrlichiosis and anaplasmosis was negative.
Because Babesia microti and Borrelia burgdorferi are transmitted by the same Ixodes ticks, clinicians should consider Babesia coinfection when Lyme disease is accompanied by anemia, thrombocytopenia, persistent fever, or evidence of hemolysis.
Ceftriaxone was discontinued. The patient was treated with azithromycin and atovaquone for babesiosis, while doxycycline was continued for 14 days for the reported Borrelia coinfection.
Why did Babesia treatment last eight weeks?
Although the patient’s parasitemia initially decreased, it later increased to 7.37% during treatment. The clinicians continued azithromycin and atovaquone rather than immediately changing the regimen.
The parasitemia subsequently declined, but Babesia parasites were still visible in red blood cells after six weeks. A blood smear performed on day 42 showed a parasitemia level of 0.15%.
Peripheral blood smears became negative beginning on day 60. Treatment was discontinued approximately eight weeks after therapy had started.
“After an extended 8-week treatment with azithromycin and atovaquone, the patient demonstrated clinical resolution of babesiosis with a negative blood smear,” the authors wrote.
The authors noted that patients with mild babesiosis are typically treated for seven to ten days. However, immunocompromised patients may require at least six weeks of therapy, depending on the severity of illness, persistence of parasitemia, and clinical response.
They also discussed alternative medications that have been used for babesiosis, including atovaquone-proguanil, clindamycin, quinine, and artemisinin. Treatment decisions should be individualized, particularly in patients with severe illness or impaired immune function.
Can prolonged Babesia infection relapse?
“Cases of prolonged parasitemia, such as in the case presented, have been known to relapse, sometimes even 2 years later.”
“Therefore, we suggest that providers consider follow-up examination after the apparent clearance of babesiosis,” the authors wrote.
Follow-up may be especially important for patients without a functioning spleen and for others who are immunocompromised. In these individuals, improvement in symptoms may not always mean that parasitemia has completely resolved.
Editor’s note: This patient’s infection was identified early enough for clinicians to monitor parasitemia with repeated blood smears. The authors did not address the treatment of individuals who are diagnosed later, after parasites are no longer visible on a peripheral blood smear. In those situations, clinicians may rely on the patient’s exposure history, symptoms, antibody testing, PCR results, and response to treatment as part of an individualized evaluation.
Frequently Asked Questions
Why is Babesia more dangerous without a spleen?
The spleen helps remove Babesia-infected red blood cells and supports the immune response against the parasite. Without a functioning spleen, the parasite may remain in the bloodstream longer and produce more severe illness.
How long is Babesia treated in someone with asplenia?
Uncomplicated babesiosis is often treated for seven to ten days. However, patients without a spleen or with other forms of immune impairment may require six weeks or longer, depending on their symptoms, parasitemia, laboratory findings, and response to treatment.
Can Babesia parasitemia increase during treatment?
Yes. In this case, the patient’s parasitemia initially improved and then increased to 7.37% before gradually declining. The treating clinicians continued first-line therapy, and blood smears eventually became negative.
Can Babesia relapse after treatment?
Yes. Relapses have been reported in patients with prolonged parasitemia, particularly when the immune system is impaired. The authors noted that relapse has occasionally occurred as long as two years after treatment.
Can Babesia and Lyme disease occur together?
Yes. Ixodes ticks can transmit both Borrelia burgdorferi and Babesia microti during the same tick bite. Coinfection may lead to more severe illness and should be considered when symptoms or laboratory abnormalities appear disproportionate for Lyme disease alone.
Clinical Takeaway
Babesia infection may be considerably more difficult to clear in patients without a functioning spleen. Although uncomplicated infections are commonly treated for seven to ten days, asplenic and other immunocompromised patients may require prolonged therapy and follow-up testing.
The rise in parasitemia during treatment did not necessarily indicate treatment failure. In this case, continued first-line therapy with azithromycin and atovaquone ultimately led to gradual clearance of the parasite. For carefully selected patients, persistence with an appropriate regimen may be preferable to changing therapy prematurely.
This case highlights the importance of recognizing asplenia as a major risk factor for prolonged Babesia infection and possible relapse.
Related Articles
Learn more about Babesia symptoms, persistent infection, and treatment:
Babesia symptoms: Diagnosis and treatment
The case of an untreated Babesia infection
Tafenoquine: Treatment for relapsing Babesia
References
- Ivancich M, Lutwick L, Shweta FNU. Trust the Process: Prolonged Babesia Parasitemia in an Elderly Man with Asplenia from the American Midwest. Am J Case Rep. 2022;23:e936326. doi:10.12659/AJCR.936326.
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 had an extensive case of babesiosis and had a fitful 4 days in ICU. I was put on atova/azithromax for 3 weeks, went off the meds, but the organism came back. I then went on atova/proguanil and azithromax for another 2 full years despite the fact I was, for all intents and purposes, free of the parasite after 10 months. I stayed on the meds for another 14 months, and after asking twice why I was still on the meds, I was “allowed” to get off the meds. I had smears and PCR’s, AOK after 10months. Any ideas why I was kept on the meds so long?