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PubMed This is a summary of 17 peer-reviewed journal articles Updated
Infectious Disease

Testing and Understanding Your Pathology Report

At a Glance

To diagnose Babesiosis, doctors use a blood smear to see parasites in your red blood cells and calculate your parasitemia percentage, or a PCR test to find the parasite's DNA. Your doctor will also check hemolysis markers like LDH and haptoglobin to measure red blood cell destruction.

Understanding your lab reports is one of the most powerful ways to participate in your recovery. When you look at your results, you will likely see a mix of tests that look for the parasite itself and tests that measure how your body is responding to the infection [1].

The Two Ways to Find the Parasite

To confirm you have Babesiosis, doctors use two primary types of tests:

  1. Peripheral Blood Smear (Microscopy): This is usually the first step. A lab technician looks at a drop of your blood under a microscope to find parasites inside your red blood cells [1]. This test is fast and allows the doctor to calculate your “parasitemia percentage” [2].
  2. PCR (Polymerase Chain Reaction): This is a highly sensitive DNA test that looks for the genetic footprint of the Babesia parasite [3]. PCR is much more powerful than a microscope; it can find the infection even when there are very few parasites in your blood, making it the “definitive” test for low-level or early infections [4][5].

Understanding ‘Parasitemia Percentage’

Parasitemia is the medical term for the amount of parasite in your blood [1]. It is expressed as a percentage—for example, a “2% parasitemia” means that 2 out of every 100 of your red blood cells are infected [2].

  • Low Parasitemia (<1-2%): Often seen in mild cases or as you begin to recover [1].
  • High Parasitemia (>10%): This is considered a severe infection and may require more intensive hospital care or advanced treatments like a red blood cell exchange [6][7].

Monitoring Your Body’s Response

Because Babesia destroys red blood cells (hemolysis), your lab report will include several “hemolysis markers.” These tell your doctor how much stress your blood and organs are under [8].

  • LDH (Lactate Dehydrogenase): This enzyme lives inside your cells. When red blood cells rupture, LDH spills into your bloodstream. High levels mean a lot of cells are being destroyed [9][10].
  • Haptoglobin: This protein “mops up” free hemoglobin from burst cells. If your haptoglobin level is very low, it means it is busy working overtime to clean up the wreckage of destroyed red blood cells [8][11].
  • Bilirubin (Indirect): When red blood cells break down, they create bilirubin. High levels of indirect bilirubin can cause jaundice (yellowing of the eyes and skin) [8][12].
  • Reticulocyte Count: This measures how many new, “baby” red blood cells your bone marrow is making. A high count shows your body is trying hard to replace the cells it has lost [8][11].

Your Diagnostic Checklist

When reviewing your records or talking to your doctor, ensure these key areas have been evaluated:

Category Key Lab Tests What It Tells You
Direct Detection Blood Smear & PCR Confirms if the parasite is present and how much is there. [1][3]
Blood Health CBC (Hemoglobin, Hematocrit, Platelets) Checks for anemia and low platelets (thrombocytopenia). [13][14]
Cell Breakdown LDH, Haptoglobin, Bilirubin Measures the severity of red blood cell destruction (hemolysis). [8][9]
Organ Function Creatinine & Liver Enzymes (ALT/AST) Monitors how your kidneys and liver are handling the infection. [9][13]
Co-infections Lyme and Anaplasma Serology/PCR Checks if the tick passed on other germs at the same time. [15]

If you are immunocompromised, your doctor may keep you on treatment until your blood smear is clear for at least two consecutive weeks to prevent a relapse [16][17].

Common questions in this guide

What does parasitemia percentage mean on my Babesiosis lab report?
Parasitemia percentage measures the amount of parasite in your blood. For example, a 2% parasitemia means that 2 out of every 100 of your red blood cells are currently infected with the Babesia parasite.
What is the difference between a blood smear and a PCR test for Babesiosis?
A blood smear involves looking at a drop of blood under a microscope to visually find the parasite. A PCR test is a highly sensitive DNA test that looks for the genetic footprint of the parasite, making it better at finding early or low-level infections that a microscope might miss.
Why is my doctor checking my LDH and haptoglobin levels?
Because the Babesia parasite destroys red blood cells, doctors measure these markers to monitor the damage. High LDH and low haptoglobin mean that a significant number of your red blood cells are currently being destroyed by the infection.
How do I know if my Babesiosis infection is clearing up?
Your doctor will repeatedly check your blood smears and hemolysis markers to ensure the parasite count is dropping. If you have a weakened immune system, you may need to continue treatment until your blood smear is completely clear for at least two weeks in a row.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my exact parasitemia percentage based on the peripheral blood smear today?
  2. 2.If my blood smear comes back negative but I still feel unwell, can we run a PCR test to check for low levels of the parasite?
  3. 3.What do my LDH and haptoglobin levels tell us about the current speed of my red blood cell breakdown?
  4. 4.Based on my lab results, am I showing any signs of kidney or liver strain from the infection?
  5. 5.How often will we repeat these blood tests to ensure the infection is truly clearing?

Questions For You

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References

References (17)
  1. 1

    Case Report: Diagnosis of Hemolytic Anemia from Babesia and Secondary Multi-Pathogen Pneumonia Using a Metagenomic Next-Generation Sequencing Approach.

    Lu Y, Zhang D, Han D, et al.

    Infection and drug resistance 2024; (17()):3785-3791 doi:10.2147/IDR.S472861.

    PMID: 39247756
  2. 2

    A Five-Week-Old Twin With Profound Anemia: A Case Report of Asymmetric Congenital Babesiosis.

    Walker S, Coray E, Ginsberg-Peltz J, Smith L

    Cureus 2022; (14(3)):e22774 doi:10.7759/cureus.22774.

    PMID: 35382190
  3. 3

    Microscopic and Molecular Detection of Camel Piroplasmosis in Gadarif State, Sudan.

    Ibrahim AM, Kadle AA, Nyingilili HS

    Veterinary medicine international 2017; (2017()):9345231 doi:10.1155/2017/9345231.

    PMID: 28293445
  4. 4

    Babesiosis as a Cause of Atraumatic Splenic Injury: Two Case Reports and a Review of Literature.

    Sung LH, Sundaram AH, Glick AL, et al.

    Journal of general internal medicine 2021; (36(12)):3869-3874 doi:10.1007/s11606-021-07117-5.

    PMID: 34549355
  5. 5

    Infection with Babesia microti in humans with non-specific symptoms in North East Poland.

    Moniuszko-Malinowska A, Swiecicka I, Dunaj J, et al.

    Infectious diseases (London, England) 2016; (48(7)):537-43 doi:10.3109/23744235.2016.1164339.

    PMID: 27118086
  6. 6

    Adjunctive treatment of clinically severe babesiosis with red blood cell exchange: a case series of nineteen patients.

    Nixon CP, Park S, Nixon CE, et al.

    Transfusion 2019; (59(8)):2629-2635 doi:10.1111/trf.15346.

    PMID: 31145479
  7. 7

    Repeat exchange transfusion for treatment of severe babesiosis.

    Radcliffe C, Krause PJ, Grant M

    Transfusion and apheresis science : official journal of the World Apheresis Association : official journal of the European Society for Haemapheresis 2019; (58(5)):638-640 doi:10.1016/j.transci.2019.07.010.

    PMID: 31526674
  8. 8

    Babesia microti Causing Intravascular Hemolysis in Immunocompetent Child, China.

    Yao J, Liu G, Zou Y, et al.

    Emerging infectious diseases 2023; (29(3)):667-669 doi:10.3201/eid2903.220888.

    PMID: 36823712
  9. 9

    Acute Kidney Injury Caused by Evans Syndrome with Systemic Lupus Erythematosus and Systemic Sclerosis.

    Matsuoka N, Watanabe H, Kurooka N, et al.

    Internal medicine (Tokyo, Japan) 2021; (60(7)):1055-1060 doi:10.2169/internalmedicine.5976-20.

    PMID: 33116016
  10. 10

    A Rare Presentation of Babesia-Associated Splenic Infarction in an Immunocompetent Young Male With Mild Parasitemia.

    Anthony JA, Nikolic D, Pepe R, Fraimow H

    Case reports in medicine 2026; (2026()):5210024 doi:10.1155/carm/5210024.

    PMID: 41488487
  11. 11

    Autoimmune hemolytic anemia associated with babesiosis.

    Narurkar R, Mamorska-Dyga A, Nelson JC, Liu D

    Biomarker research 2017; (5()):14 doi:10.1186/s40364-017-0095-6.

    PMID: 28405337
  12. 12

    Severe babesiosis with associated splenic infarcts and asplenia.

    Sporn ZA, Fenves AZ, Sykes DB, Al-Samkari H

    Proceedings (Baylor University. Medical Center) 2021; (34(5)):597-599 doi:10.1080/08998280.2021.1930632.

    PMID: 34456483
  13. 13

    Severe Babesiosis With Multifactorial Hemolysis and Pulmonary Complications in an Asplenic Patient at a Tertiary Cancer Center.

    Ayana G, Carlson S, Keraga BK, et al.

    Cureus 2025; (17(10)):e94343 doi:10.7759/cureus.94343.

    PMID: 41220440
  14. 14

    Parasite burden and red blood cell exchange transfusion for babesiosis.

    O'Bryan J, Gokhale A, Hendrickson JE, Krause PJ

    Journal of clinical apheresis 2021; (36(1)):127-134 doi:10.1002/jca.21853.

    PMID: 33179803
  15. 15

    Beyond Human Babesiosis: Prevalence and Association of Babesia Coinfection with Mortality in the United States, 2015-2022: A Retrospective Cohort Study.

    Ssentongo P, Venugopal N, Zhang Y, et al.

    Open forum infectious diseases 2024; (11(10)):ofae504 doi:10.1093/ofid/ofae504.

    PMID: 39381028
  16. 16

    Relapsing Babesiosis With Molecular Evidence of Resistance to Certain Antimicrobials Commonly Used to Treat Babesia microti Infections.

    Marcos LA, Wormser GP

    Open forum infectious diseases 2023; (10(8)):ofad391 doi:10.1093/ofid/ofad391.

    PMID: 37539067
  17. 17

    Trust the Process: Prolonged Babesia Parasitemia in an Elderly Man with Asplenia from the American Midwest.

    Ivancich M, Lutwick L, Shweta FNU

    The American journal of case reports 2022; (23()):e936326 doi:10.12659/AJCR.936326.

    PMID: 35844076

This page explains Babesiosis lab tests and pathology terms for educational purposes only. Always consult your doctor or infectious disease specialist to interpret your specific blood work.

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