What are the symptoms of Babesia (Babesiosis) infection?

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Last updated: April 17, 2025View editorial policy

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From the Guidelines

Babesia infection typically presents with flu-like symptoms, including fever, chills, sweats, myalgia, arthralgia, anorexia, nausea, vomiting, or fatigue, as reported in the clinical practice guidelines by the Infectious Diseases Society of America 1. The symptoms of babesiosis can range in severity from asymptomatic to rapidly fatal, with most patients experiencing a viral infection–like illness. Common symptoms include:

  • Fever
  • Chills
  • Sweats
  • Myalgia
  • Arthralgia
  • Anorexia
  • Nausea
  • Vomiting
  • Fatigue On physical examination, patients may exhibit:
  • Fever
  • Splenomegaly
  • Hepatomegaly
  • Jaundice Laboratory findings may include:
  • Hemolytic anemia with an elevated reticulocyte count
  • Thrombocytopenia
  • Proteinuria
  • Elevated levels of liver enzymes, blood urea nitrogen, and creatinine, as noted in the study published in Clinical Infectious Diseases 1. It is essential to recognize that babesiosis symptoms can be easily confused with malaria or Lyme disease since they share similar presentations, and diagnosis typically requires blood tests, including blood smears, PCR testing, or antibody tests. Early recognition and treatment are crucial to prevent complications, especially in high-risk individuals, such as the elderly, immunocompromised, or splenectomized individuals, as emphasized in the clinical practice guidelines 1.

From the Research

Symptoms of Babesia

  • Babesiosis is an increasingly recognized parasitic infection with manifestations that range from a subclinical or mild flu-like illness to life-threatening disease 2
  • The disease can cause severe hemolytic anemia, disseminated intravascular coagulation, acute renal failure, and respiratory failure 2
  • Symptoms can include fever, anemia, thrombocytopenia, and an increase in hepatic enzymes 3
  • In severe cases, babesiosis can be life-threatening, especially in immunocompromised individuals, those who have undergone splenectomy, and the elderly 2, 4

Risk Factors

  • Immunocompromised individuals are at a higher risk of developing severe babesiosis 2, 5, 4
  • Splenectomy and advanced age are also risk factors for a more severe clinical course 2
  • Highly immunocompromised patients may respond suboptimally to treatment and are at risk of developing resistance to certain medications 5

Treatment

  • The most effective chemotherapeutic regimen is clindamycin plus quinine, but this may not always be effective in severe cases 2
  • Atovaquone and azithromycin is an alternative treatment that has been shown to be as effective as clindamycin and quinine, with fewer adverse reactions 6
  • In severe cases, whole-blood exchange transfusion may be necessary to lower the parasite load and replace the patient's plasma 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Atovaquone and azithromycin treatment for babesiosis in an infant.

The Pediatric infectious disease journal, 2007

Research

Management strategies for human babesiosis.

Expert review of anti-infective therapy, 2020

Research

Emergence of resistance to azithromycin-atovaquone in immunocompromised patients with Babesia microti infection.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2010

Research

Atovaquone and azithromycin for the treatment of babesiosis.

The New England journal of medicine, 2000

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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