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Clinical manifestations, diagnosis, treatment, and prevention of babesiosis

Jeffrey A Gelfand, MD, FACP
Edouard G Vannier, PhD
Section Editor
Johanna Daily, MD, MSc
Deputy Editor
Elinor L Baron, MD, DTMH


Babesiosis is an infectious disease caused by protozoa of the genus Babesia. Babesia protozoa infect vertebrate animals and cause lysis of host red blood cells [1]. The zoonotic cycle is maintained by tick vectors. Human infection is accidental; humans are not definitive reservoir hosts. Babesiosis may also be acquired by blood transfusion, particularly in areas endemic for Babesia microti and B. duncani.

The main etiologic agents of human babesiosis are B. microti in the northeastern and upper midwestern regions of the United States and B. divergens in Europe [2]. Other Babesia species are occasionally but rarely identified in humans (eg, B. divergens-like organisms in the Midwest and on the West Coast of the United States; B. duncani on the West Coast of the United States; and B. venatorum in Europe and mainland China).

Treatment modalities depend on the species of Babesia and the immune status of the host. The clinical manifestations, diagnosis, treatment, and prevention of babesiosis will be reviewed here. The epidemiology and pathogenesis of this infection are discussed separately. (See "Epidemiology and pathogenesis of babesiosis".)


Babesia infections range from asymptomatic to severe and are sometimes fatal. The severity of infection depends on the Babesia species and the immune status of the host.

B. microti — B. microti is the predominant species in the United States, whereas B. microti-like organisms have been implicated in Europe, Asia, and Australia. Clinical manifestations may be absent or range from mild to severe, sometimes resulting in death. Symptoms typically develop one to six weeks after the bite of an infected tick [2,3]. An incubation period of 12 weeks was described in one case report. The median interval from transfusion to onset of symptoms is 37 days (range 11 to 176 days) [4].


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Literature review current through: Aug 2017. | This topic last updated: Mar 23, 2017.
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  1. Sanchez E, Vannier E, Wormser GP, Hu LT. Diagnosis, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: A Review. JAMA 2016; 315:1767.
  2. Vannier E, Krause PJ. Human babesiosis. N Engl J Med 2012; 366:2397.
  3. Vannier EG, Diuk-Wasser MA, Ben Mamoun C, Krause PJ. Babesiosis. Infect Dis Clin North Am 2015; 29:357.
  4. Herwaldt BL, Linden JV, Bosserman E, et al. Transfusion-associated babesiosis in the United States: a description of cases. Ann Intern Med 2011; 155:509.
  5. Semel ME, Tavakkolizadeh A, Gates JD. Babesiosis in the immediate postoperative period after splenectomy for trauma. Surg Infect (Larchmt) 2009; 10:553.
  6. Wormser GP, Lombardo G, Silverblatt F, et al. Babesiosis as a cause of fever in patients undergoing a splenectomy. Am Surg 2011; 77:345.
  7. Krause PJ, Spielman A, Telford SR 3rd, et al. Persistent parasitemia after acute babesiosis. N Engl J Med 1998; 339:160.
  8. Hatcher JC, Greenberg PD, Antique J, Jimenez-Lucho VE. Severe babesiosis in Long Island: review of 34 cases and their complications. Clin Infect Dis 2001; 32:1117.
  9. Krause PJ, Telford SR 3rd, Spielman A, et al. Concurrent Lyme disease and babesiosis. Evidence for increased severity and duration of illness. JAMA 1996; 275:1657.
  10. Reubush TK 2nd, Cassaday PB, Marsh HJ, et al. Human babesiosis on Nantucket Island. Clinical features. Ann Intern Med 1977; 86:6.
  11. White DJ, Talarico J, Chang HG, et al. Human babesiosis in New York State: Review of 139 hospitalized cases and analysis of prognostic factors. Arch Intern Med 1998; 158:2149.
  12. Wormser GP, Villafuerte P, Nolan SM, et al. Neutropenia in Congenital and Adult Babesiosis. Am J Clin Pathol 2015; 144:94.
  13. Krause PJ, Lepore T, Sikand VK, et al. Atovaquone and azithromycin for the treatment of babesiosis. N Engl J Med 2000; 343:1454.
  14. Ruebush TK 2nd, Juranek DD, Chisholm ES, et al. Human babesiosis on Nantucket Island. Evidence for self-limited and subclinical infections. N Engl J Med 1977; 297:825.
  15. Taiwo B, Lee C, Venkat D, et al. Can tumor necrosis factor alpha blockade predispose to severe babesiosis? Arthritis Rheum 2007; 57:179.
  16. Cullen G, Sands BE, Yajnik V. Babesiosis in a patient on infliximab for Crohn's disease. Inflamm Bowel Dis 2010; 16:1269.
  17. Bogoch II, Davis BT, Hooper DC. Severe babesiosis in a patient treated with a tumor necrosis factor α antagonist. Clin Infect Dis 2012; 54:1215.
  18. Florescu D, Sordillo PP, Glyptis A, et al. Splenic infarction in human babesiosis: two cases and discussion. Clin Infect Dis 2008; 46:e8.
  19. Froberg MK, Dannen D, Bernier N, et al. Case report: spontaneous splenic rupture during acute parasitemia of Babesia microti. Ann Clin Lab Sci 2008; 38:390.
  20. Kuwayama DP, Briones RJ. Spontaneous splenic rupture caused by Babesia microti infection. Clin Infect Dis 2008; 46:e92.
  21. Woolley AE, Montgomery MW, Savage WJ, et al. Post-Babesiosis Warm Autoimmune Hemolytic Anemia. N Engl J Med 2017; 376:939.
  22. Zintl A, Mulcahy G, Skerrett HE, et al. Babesia divergens, a bovine blood parasite of veterinary and zoonotic importance. Clin Microbiol Rev 2003; 16:622.
  23. Gorenflot A, Moubri K, Precigout E, et al. Human babesiosis. Ann Trop Med Parasitol 1998; 92:489.
  24. Martinot M, Zadeh MM, Hansmann Y, et al. Babesiosis in immunocompetent patients, Europe. Emerg Infect Dis 2011; 17:114.
  25. Beattie JF, Michelson ML, Holman PJ. Acute babesiosis caused by Babesia divergens in a resident of Kentucky. N Engl J Med 2002; 347:697.
  26. Herwaldt B, Persing DH, Précigout EA, et al. A fatal case of babesiosis in Missouri: identification of another piroplasm that infects humans. Ann Intern Med 1996; 124:643.
  27. Herwaldt BL, de Bruyn G, Pieniazek NJ, et al. Babesia divergens-like infection, Washington State. Emerg Infect Dis 2004; 10:622.
  28. Persing DH, Herwaldt BL, Glaser C, et al. Infection with a babesia-like organism in northern California. N Engl J Med 1995; 332:298.
  29. Quick RE, Herwaldt BL, Thomford JW, et al. Babesiosis in Washington State: a new species of Babesia? Ann Intern Med 1993; 119:284.
  30. Herwaldt BL, Kjemtrup AM, Conrad PA, et al. Transfusion-transmitted babesiosis in Washington State: first reported case caused by a WA1-type parasite. J Infect Dis 1997; 175:1259.
  31. Kjemtrup AM, Lee B, Fritz CL, et al. Investigation of transfusion transmission of a WA1-type babesial parasite to a premature infant in California. Transfusion 2002; 42:1482.
  32. Bloch EM, Herwaldt BL, Leiby DA, et al. The third described case of transfusion-transmitted Babesia duncani. Transfusion 2012; 52:1517.
  33. Häselbarth K, Tenter AM, Brade V, et al. First case of human babesiosis in Germany - Clinical presentation and molecular characterisation of the pathogen. Int J Med Microbiol 2007; 297:197.
  34. Herwaldt BL, Cacciò S, Gherlinzoni F, et al. Molecular characterization of a non-Babesia divergens organism causing zoonotic babesiosis in Europe. Emerg Infect Dis 2003; 9:942.
  35. Blum S, Gattringer R, Haschke E, et al. The case: hemolysis and acute renal failure. Babesiosis. Kidney Int 2011; 80:681.
  36. Sun Y, Li SG, Jiang JF, et al. Babesia venatorum Infection in Child, China. Emerg Infect Dis 2014; 20:896.
  37. Jiang JF, Zheng YC, Jiang RR, et al. Epidemiological, clinical, and laboratory characteristics of 48 cases of "Babesia venatorum" infection in China: a descriptive study. Lancet Infect Dis 2015; 15:196.
  38. Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes Tick-Borne Pathogens: Ecological, Epidemiological, and Clinical Consequences. Trends Parasitol 2016; 32:30.
  39. Krause PJ, McKay K, Thompson CA, et al. Disease-specific diagnosis of coinfecting tickborne zoonoses: babesiosis, human granulocytic ehrlichiosis, and Lyme disease. Clin Infect Dis 2002; 34:1184.
  40. Krause PJ, Narasimhan S, Wormser GP, et al. Human Borrelia miyamotoi infection in the United States. N Engl J Med 2013; 368:291.
  41. Molloy PJ, Telford SR 3rd, Chowdri HR, et al. Borrelia miyamotoi Disease in the Northeastern United States: A Case Series. Ann Intern Med 2015; 163:91.
  42. Centers for Disease Control and Prevention (CDC). Babesiosis surveillance - 18 States, 2011. MMWR Morb Mortal Wkly Rep 2012; 61:505.
  43. Wormser GP, Dattwyler RJ, Shapiro ED, et al. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis 2006; 43:1089.
  44. Kjemtrup AM, Conrad PA. Human babesiosis: an emerging tick-borne disease. Int J Parasitol 2000; 30:1323.
  45. Conrad PA, Kjemtrup AM, Carreno RA, et al. Description of Babesia duncani n.sp. (Apicomplexa: Babesiidae) from humans and its differentiation from other piroplasms. Int J Parasitol 2006; 36:779.
  46. Holman PJ. Phylogenetic and biologic evidence that Babesia divergens is not endemic in the United States. Ann N Y Acad Sci 2006; 1081:518.
  47. Bloch EM, Levin AE, Williamson PC, et al. A prospective evaluation of chronic Babesia microti infection in seroreactive blood donors. Transfusion 2016; 56:1875.
  48. Wang G, Villafuerte P, Zhuge J, et al. Comparison of a quantitative PCR assay with peripheral blood smear examination for detection and quantitation of Babesia microti infection in humans. Diagn Microbiol Infect Dis 2015; 82:109.
  49. Raffalli J, Wormser GP. Persistence of babesiosis for >2 years in a patient on rituximab for rheumatoid arthritis. Diagn Microbiol Infect Dis 2016; 85:231.
  50. Teal AE, Habura A, Ennis J, et al. A new real-time PCR assay for improved detection of the parasite Babesia microti. J Clin Microbiol 2012; 50:903.
  51. Rollend L, Bent SJ, Krause PJ, et al. Quantitative PCR for detection of Babesia microti in Ixodes scapularis ticks and in human blood. Vector Borne Zoonotic Dis 2013; 13:784.
  52. Moritz ED, Winton CS, Johnson ST, et al. Investigational screening for Babesia microti in a large repository of blood donor samples from nonendemic and endemic areas of the United States. Transfusion 2014; 54:2226.
  53. Wilson M, Glaser KC, Adams-Fish D, et al. Development of droplet digital PCR for the detection of Babesia microti and Babesia duncani. Exp Parasitol 2015; 149:24.
  54. Bloch EM, Lee TH, Krause PJ, et al. Development of a real-time polymerase chain reaction assay for sensitive detection and quantitation of Babesia microti infection. Transfusion 2013; 53:2299.
  55. Leiby DA, Johnson ST, Won KY, et al. A longitudinal study of Babesia microti infection in seropositive blood donors. Transfusion 2014; 54:2217.
  56. Krause PJ, Ryan R, Telford S 3rd, et al. Efficacy of immunoglobulin M serodiagnostic test for rapid diagnosis of acute babesiosis. J Clin Microbiol 1996; 34:2014.
  57. Krause PJ, Telford SR 3rd, Ryan R, et al. Diagnosis of babesiosis: evaluation of a serologic test for the detection of Babesia microti antibody. J Infect Dis 1994; 169:923.
  58. Ruebush TK 2nd, Chisholm ES, Sulzer AJ, Healy GR. Development and persistence of antibody in persons infected with Babesia microti. Am J Trop Med Hyg 1981; 30:291.
  59. Duh D, Jelovsek M, Avsic-Zupanc T. Evaluation of an indirect fluorescence immunoassay for the detection of serum antibodies against Babesia divergens in humans. Parasitology 2007; 134:179.
  60. Hunfeld KP, Hildebrandt A, Gray JS. Babesiosis: recent insights into an ancient disease. Int J Parasitol 2008; 38:1219.
  61. Gulersen M, Brost BC, Bobrovnikov V, Bornstein E. Acute Babesiosis in Pregnancy: A Novel Imitator of Hemolysis, Elevated Liver Enzymes, and Low Platelet Count Syndrome. Obstet Gynecol 2016; 128:197.
  62. Ray WA, Murray KT, Hall K, et al. Azithromycin and the risk of cardiovascular death. N Engl J Med 2012; 366:1881.
  63. Weiss LM, Wittner M, Tanowitz HB. The treatment of babesiosis. N Engl J Med 2001; 344:773.
  64. Wittner M, Rowin KS, Tanowitz HB, et al. Successful chemotherapy of transfusion babesiosis. Ann Intern Med 1982; 96:601.
  65. White NJ. Cardiotoxicity of antimalarial drugs. Lancet Infect Dis 2007; 7:549.
  66. Wroblewski HA, Kovacs RJ, Kingery JR, et al. High risk of QT interval prolongation and torsades de pointes associated with intravenous quinidine used for treatment of resistant malaria or babesiosis. Antimicrob Agents Chemother 2012; 56:4495.
  67. Krause PJ, Gewurz BE, Hill D, et al. Persistent and relapsing babesiosis in immunocompromised patients. Clin Infect Dis 2008; 46:370.
  68. Stowell CP, Gelfand JA, Shepard JA, Kratz A. Case records of the Massachusetts General Hospital. Case 17-2007. A 25-year-old woman with relapsing fevers and recent onset of dyspnea. N Engl J Med 2007; 356:2313.
  69. Falagas ME, Klempner MS. Babesiosis in patients with AIDS: a chronic infection presenting as fever of unknown origin. Clin Infect Dis 1996; 22:809.
  70. Wormser GP, Prasad A, Neuhaus E, et al. Emergence of resistance to azithromycin-atovaquone in immunocompromised patients with Babesia microti infection. Clin Infect Dis 2010; 50:381.
  71. Lemieux JE, Tran AD, Freimark L, et al. A global map of genetic diversity in Babesia microti reveals strong population structure and identifies variants associated with clinical relapse. Nat Microbiol 2016; 1:16079.
  72. Shaio MF, Yang KD. Response of babesiosis to a combined regimen of quinine and azithromycin. Trans R Soc Trop Med Hyg 1997; 91:214.
  73. Shih CM, Wang CC. Ability of azithromycin in combination with quinine for the elimination of babesial infection in humans. Am J Trop Med Hyg 1998; 59:509.
  74. Vyas JM, Telford SR, Robbins GK. Treatment of refractory Babesia microti infection with atovaquone-proguanil in an HIV-infected patient: case report. Clin Infect Dis 2007; 45:1588.
  75. Schwartz J, Padmanabhan A, Aqui N, et al. Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue. J Clin Apher 2016; 31:149.
  76. Saifee NH, Krause PJ, Wu Y. Apheresis for babesiosis: Therapeutic parasite reduction or removal of harmful toxins or both? J Clin Apher 2016; 31:454.
  77. Jacoby GA, Hunt JV, Kosinski KS, et al. Treatment of transfusion-transmitted babesiosis by exchange transfusion. N Engl J Med 1980; 303:1098.
  78. Spaete J, Patrozou E, Rich JD, Sweeney JD. Red cell exchange transfusion for babesiosis in Rhode Island. J Clin Apher 2009; 24:97.
  79. Raoult D, Soulayrol L, Toga B, et al. Babesiosis, pentamidine, and cotrimoxazole. Ann Intern Med 1987; 107:944.