What are the signs of Babesia infection?

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Last updated: March 21, 2025View editorial policy

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From the Guidelines

To diagnose Babesia infection, look for symptoms such as fever, fatigue, chills, sweating, headache, muscle aches, and sometimes jaundice, and confirm the diagnosis through blood tests, including blood smears, PCR tests, or antibody tests, as recommended by the Infectious Diseases Society of America 1. The symptoms of Babesia infection typically appear 1-4 weeks after a tick bite. Some key points to consider when diagnosing Babesia infection include:

  • The most definitive way to diagnose Babesia infection is through blood tests, including blood smears where laboratory technicians can directly observe the parasites in red blood cells, PCR tests that detect Babesia DNA, or antibody tests that show your immune response to the infection 1.
  • If you suspect you have Babesia, especially after a tick bite or spending time in wooded areas where ticks are common, you should see a doctor immediately 1.
  • Treatment typically involves antiparasitic medications like atovaquone plus azithromycin, or clindamycin plus quinine for 7-10 days 1.
  • Babesia infection can be serious, particularly in people with weakened immune systems, the elderly, or those without a spleen, so prompt diagnosis and treatment are important 1. It is essential to note that the diagnosis of Babesia infection should be considered "stat" and testing performed as rapidly as possible, and requests for malaria and babesiosis diagnosis should be considered "stat" and testing performed as rapidly as possible 1.

From the Research

Signs of Babesia Infection

The signs of Babesia infection can vary from mild to severe and include:

  • Fever 2, 3, 4, 5, 6
  • Headache 3, 5, 6
  • Chills 3, 5, 6
  • Myalgia (muscle pain) 3, 5, 6
  • Fatigue 3, 5, 6
  • Anemia 4, 6
  • Thrombocytopenia (low platelet count) 6
  • Hemolytic anemia (a condition where the red blood cells are destroyed faster than they can be made) 4
  • Disseminated intravascular coagulation (a condition where blood clots form in small blood vessels throughout the body) 4
  • Acute renal failure (kidney failure) 4
  • Respiratory failure 4

Risk Factors for Severe Babesia Infection

Certain individuals are at a higher risk of developing severe Babesia infection, including:

  • Immunocompromised individuals (those with weakened immune systems) 2, 4, 5
  • Older adults 3, 5
  • Individuals with splenectomy (removal of the spleen) 4, 5
  • Individuals with advanced age 4, 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Persistent and relapsing babesiosis in immunocompromised patients.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2008

Research

Human Babesiosis.

Infectious disease clinics of North America, 2022

Research

[Clinical characteristics, diagnosis and treatment of human babesiosis: a review].

Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control, 2020

Research

Babesiosis diagnosis and treatment.

Vector borne and zoonotic diseases (Larchmont, N.Y.), 2003

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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