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

Symptoms, Progression, and Co-infections

At a Glance

Babesiosis is a tick-borne infection that destroys red blood cells, causing fatigue, air hunger, fevers, and sometimes dark urine or jaundice. Symptoms typically begin 1-4 weeks after a tick bite. Many patients also contract co-infections like Lyme disease, which can prolong recovery.

The way Babesiosis feels can vary significantly from person to person. While some people may have no symptoms at all, others experience a flu-like illness that can become quite serious [1]. Because the parasite lives inside your red blood cells, many of the symptoms you feel are a direct result of your body trying to manage those infected cells [2].

The Waiting Period (Incubation)

Symptoms do not appear immediately after exposure. The time it takes for the infection to show up, known as the incubation period, depends on how you were exposed:

  • Tick Bite: Symptoms usually appear 1 to 4 weeks after the bite [1][3].
  • Blood Transfusion: Because the parasite is introduced directly into the bloodstream in larger amounts, the wait can be longer, typically 1 to 9 weeks, though it has been known to take several months in rare cases [1][4].

Symptoms of Red Blood Cell Breakdown

The core of Babesiosis is hemolysis, which is the medical term for the destruction of red blood cells [5]. As the parasites multiply, they cause red blood cells to rupture [6]. This leads to hemolytic anemia, which causes specific symptoms:

  • Fatigue and Air Hunger: With fewer healthy red blood cells to carry oxygen, you may feel profoundly tired and experience a severe shortness of breath that patients often describe as “air hunger” [5][1].
  • Jaundice: As blood cells break down, they release a yellow substance called bilirubin. This can cause a yellowing of the skin or the whites of the eyes [5][7].
  • Dark Urine: When red blood cells burst, the released hemoglobin is filtered by the kidneys, which can turn your urine a dark, tea-colored, or “cola” hue [5]. If you notice dark urine or jaundice, contact your doctor immediately.

Other common symptoms include high fevers, drenching night sweats, chills, and muscle aches [3][5].

What to Expect for Recovery

When starting treatment, many patients wonder how quickly they will feel better. While everyone is different, a typical timeline looks like this:

  • Days 2 to 4: Fevers, chills, and the most acute flu-like symptoms often begin to fade after starting medication.
  • Weeks 1 to 4: “Air hunger” and severe fatigue may persist even after the parasites are cleared from your blood. Your body needs time to rebuild its red blood cell supply.
  • Months 1 to 3: Mild fatigue or lingering weakness can last for several months as your body fully recovers and replenishes its iron stores [8].

The Complexity of Co-infections

It is very common for the tick that carries Babesiosis to also carry other germs. In fact, about 40% of people with Babesiosis in the U.S. also have another tick-borne illness [9].

  • Lyme Disease: Caused by the bacterium Borrelia burgdorferi, this is the most common co-infection [9]. It often presents with a “bullseye” rash, joint pain, or facial drooping.
  • Anaplasmosis: This bacterial infection can cause severe headaches, low white blood cell counts, and high fever [9].

When you have more than one infection at once, your symptoms may be more severe or last longer than they would with just one [10][11]. If you aren’t getting better as expected on Babesiosis treatment, your doctor may need to look closer for these “hidden” co-infections [12].

Who is Most at Risk?

Most healthy people recover well from Babesiosis, but certain factors can lead to a more difficult “progression” of the disease:

  • Asplenia: The spleen is the body’s primary filter for removing damaged red blood cells [13]. If your spleen has been removed, the infection can become very severe because your body cannot clear the parasites effectively [14].
  • Age and Immunity: Adults over age 50 and those with weakened immune systems (due to cancer, HIV, or medications like rituximab) are at a higher risk for persistent or relapsing symptoms [15][16][17].

Common questions in this guide

How long does it take for Babesiosis symptoms to appear?
Symptoms typically appear 1 to 4 weeks after a tick bite. If the infection was transmitted through a blood transfusion, it usually takes 1 to 9 weeks for symptoms to show, though it can occasionally take several months.
What is "air hunger" in Babesiosis?
Air hunger is a severe shortness of breath caused by the destruction of red blood cells. Since you have fewer healthy red blood cells to carry oxygen throughout your body, you may feel profoundly tired and unable to catch your breath.
Why does Babesiosis cause dark urine or yellow skin?
Babesiosis parasites destroy red blood cells in your body. This breakdown releases a yellow substance called bilirubin, causing yellowing of the skin or eyes (jaundice), and hemoglobin, which is filtered by the kidneys and turns your urine a dark, tea-like color.
Can I have Lyme disease and Babesiosis at the same time?
Yes, about 40% of people with Babesiosis in the U.S. also have another tick-borne illness like Lyme disease or Anaplasmosis. Having multiple infections at once can make your symptoms more severe and prolong your overall recovery time.
How long does it take to recover from Babesiosis?
Fevers and acute flu-like symptoms usually fade within a few days of starting treatment. However, fatigue and shortness of breath can persist for weeks, and mild weakness may last for several months as your body slowly replaces its missing red blood cells.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Am I being tested for co-infections like Lyme disease and Anaplasmosis, since they come from the same ticks?
  2. 2.Based on my blood tests, what is my current level of parasitemia (percentage of infected red blood cells)?
  3. 3.Do I have any risk factors, like issues with my spleen or immune system, that might make my symptoms more severe?
  4. 4.Is the dark color of my urine a sign of hemolysis, and how will we monitor my kidney function?
  5. 5.If my symptoms don't improve on the initial treatment, what is our next step for managing potential co-infections?

Questions For You

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References

References (17)
  1. 1

    Transfusion-transmitted and community-acquired babesiosis in New York, 2004 to 2015.

    Linden JV, Prusinski MA, Crowder LA, et al.

    Transfusion 2018; (58(3)):660-668 doi:10.1111/trf.14476.

    PMID: 29383735
  2. 2

    Spreading of Human Babesiosis in China: Current Epidemiological Status and Future Challenges.

    Chen M, Liu Q, Xue J, et al.

    China CDC weekly 2020; (2(33)):634-637 doi:10.46234/ccdcw2020.176.

    PMID: 34594726
  3. 3

    Prevalence of Babesia in Canadian blood donors: June-October 2018.

    Tonnetti L, O'Brien SF, Grégoire Y, et al.

    Transfusion 2019; (59(10)):3171-3176 doi:10.1111/trf.15470.

    PMID: 31385317
  4. 4

    A pilot serosurvey of Babesia microti in Chinese blood donors.

    Bloch EM, Yang Y, He M, et al.

    Vox sanguinis 2018; (113(4)):345-349 doi:10.1111/vox.12648.

    PMID: 29582438
  5. 5

    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
  6. 6

    Babesia divergens host cell egress is mediated by essential and druggable kinases and proteases.

    Elsworth B, Keroack CD, Rezvani Y, et al.

    Nature microbiology 2026; (11(2)):492-506 doi:10.1038/s41564-025-02238-7.

    PMID: 41593365
  7. 7

    Risk Factors for Severe Infection, Hospitalization, and Prolonged Antimicrobial Therapy in Patients with Babesiosis.

    Mareedu N, Schotthoefer AM, Tompkins J, et al.

    The American journal of tropical medicine and hygiene 2017; (97(4)):1218-1225 doi:10.4269/ajtmh.17-0146.

    PMID: 28722598
  8. 8

    A Prospective Cohort Longitudinal Study of Human Acute Babesiosis: Quality of Life and Severity of Symptoms Through 1-Year Follow-up.

    Zamor R, Zhang X, Lamba P, et al.

    Open forum infectious diseases 2025; (12(12)):ofaf668 doi:10.1093/ofid/ofaf668.

    PMID: 41356266
  9. 9

    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
  10. 10

    Investigating disease severity in an animal model of concurrent babesiosis and Lyme disease.

    Bhanot P, Parveen N

    International journal for parasitology 2019; (49(2)):145-151 doi:10.1016/j.ijpara.2018.06.006.

    PMID: 30367867
  11. 11

    Documentation of a false positive Lyme disease serologic test in a patient with untreated Babesia microti infection carries implications for accurately determining the frequency of Lyme disease coinfections.

    Wormser GP

    Diagnostic microbiology and infectious disease 2021; (101(1)):115429 doi:10.1016/j.diagmicrobio.2021.115429.

    PMID: 34133997
  12. 12

    Emerging babesiosis in the mid-Atlantic: autochthonous human babesiosis cases and Babesia microti (Piroplasmida: Babesiidae) in Ixodes scapularis (Acari: Ixodidae) and Ixodes keiransi (Acari: Ixodidae) ticks from Delaware, Maryland, Virginia, West Virginia, and the District of Columbia, 2009 to 2024.

    Stromdahl EY, Feldman KA, Nadolny RM, et al.

    Journal of medical entomology 2025; (62(4)):995-1008 doi:10.1093/jme/tjaf054.

    PMID: 40261095
  13. 13

    Possible Transfusion-Transmitted Babesia divergens-like/MO-1 Infection in an Arkansas Patient.

    Burgess MJ, Rosenbaum ER, Pritt BS, et al.

    Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2017; (64(11)):1622-1625 doi:10.1093/cid/cix216.

    PMID: 28329282
  14. 14

    A Case of Babesiosis in a Pregnant Patient Treated with Red Blood Cell Exchange Transfusion.

    Abittan B, Nizam A, Oey M, et al.

    Case reports in obstetrics and gynecology 2019; (2019()):9869323 doi:10.1155/2019/9869323.

    PMID: 31275683
  15. 15

    High seroprevalence of Babesia antibodies among Borrelia burgdorferi-infected humans in Sweden.

    Svensson J, Hunfeld KP, Persson KEM

    Ticks and tick-borne diseases 2019; (10(1)):186-190 doi:10.1016/j.ttbdis.2018.10.007.

    PMID: 30389326
  16. 16

    Broad Antimicrobial Resistance in a Case of Relapsing Babesiosis Successfully Treated With Tafenoquine.

    Rogers R, Krause PJ, Norris AM, et al.

    Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2023; (76(4)):741-744 doi:10.1093/cid/ciac473.

    PMID: 35684960
  17. 17

    Tick-borne illness after transplantation: Case and review.

    Mascarenhas TR, Silibovsky RS, Singh P, Belden KA

    Transplant infectious disease : an official journal of the Transplantation Society 2018; (20(2)):e12830 doi:10.1111/tid.12830.

    PMID: 29277955

This information about Babesiosis symptoms and disease progression is for educational purposes only. Always consult your healthcare provider for an accurate diagnosis, especially if you experience severe signs like dark urine or jaundice.

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