Diagnosis and Management of Babesiosis

Publication Date: January 15, 2021
Last Updated: March 22, 2022


For diagnostic confirmation of acute babesiosis, IDSA recommends peripheral blood smear examination or PCR rather than antibody testing. ( S , M)

Comment: The diagnosis of babesiosis should be based on epidemiological risk factors and clinical evidence, and confirmed by blood smear examination or PCR.


For patients with a positive Babesia antibody test, IDSA recommends confirmation with blood smear or PCR before treatment is considered. ( S , M)

Comment: A single positive antibody test is not sufficient to establish a diagnosis of babesiosis because Babesia antibodies can persist in blood for a year or more following apparent clearance of infection, with or without treatment.



IDSA recommends treating babesiosis with the combination of atovaquone plus azithromycin or the combination of clindamycin plus quinine. ( S , M)
Comment: Atovaquone plus azithromycin is the preferred antimicrobial combination for patients experiencing babesiosis while clindamycin plus quinine is the alternative choice. The duration of treatment is 7–10 days in immunocompetent patients but often is extended when the patient is immunocompromised (Table 1).
In selected patients with severe babesiosis, IDSA suggests exchange transfusion using red blood cells. ( W , L)

Comment: Exchange transfusion may be considered for patients with high-grade parasitemia (>10%) or who have any one or more of the following: severe hemolytic anemia and/or severe pulmonary, renal, or hepatic compromise. Expert consultation with a transfusion services physician or hematologist in conjunction with an infectious diseases specialist is strongly advised.

For immunocompetent patients, IDSA recommends monitoring Babesia parasitemia during treatment of acute illness using peripheral blood smears but recommend against testing for parasitemia once symptoms have resolved. ( S , M)
For immunocompromised patients, IDSA suggests monitoring Babesia parasitemia using peripheral blood smears even after they become asymptomatic and until blood smears are negative. PCR testing should be considered if blood smears have become negative but symptoms persist. ( W , M)

Recommendation Grading




Diagnosis and Management of Babesiosis

Authoring Organization

Endorsing Organizations

Publication Month/Year

January 15, 2021

Last Updated Month/Year

July 11, 2023

Supplemental Implementation Tools

Document Type


External Publication Status


Country of Publication


Inclusion Criteria

Female, Male, Adolescent, Adult, Child, Infant, Older adult

Health Care Settings

Ambulatory, Hospital

Intended Users

Physician, epidemiology infection prevention, nurse, nurse practitioner, physician assistant


Diagnosis, Management, Treatment

Diseases/Conditions (MeSH)

D001404 - Babesiosis


clindamycin, babesiosis

Supplemental Methodology Resources

Data Supplement


Number of Source Documents
Literature Search Start Date
March 1, 2016
Literature Search End Date
April 1, 2019