Key Points
- Babesiosis is a disease caused by intraerythrocytic protozoa of the genus Babesia that are transmitted throughout the world by hard-bodied ticks.
- More than 100 Babesia species infect a wide variety of wild and domestic animals.
- Babesiosis has long been recognized as an important disease of livestock with significant economic impact in many parts of the world.
- A subset of Babesia species infect humans.
- More than 100 Babesia species infect a wide variety of wild and domestic animals.
- More than 2,000 cases of babesiosis are reported to the CDC annually, but several lines of evidence indicate that the actual number of cases is higher and increasing (Figure 3).
- Clinical manifestations of babesiosis include fever, fatigue, chills, sweats, headache, and anorexia.
- Severe babesiosis requires hospital admission and can be complicated by marked anemia, acute respiratory distress syndrome, disseminated intravascular coagulation, congestive heart failure, renal and liver impairment/failure, shock, splenic infarct or rupture, warm autoimmune hemolytic anemia, and/or fatal outcome.
- A diagnosis should be considered in a patient who resides in or has traveled to an endemic area, experiences clinical symptoms that are consistent with babesiosis, and has characteristic laboratory test abnormalities.
- The diagnosis is confirmed with the identification of Babesia parasites by microscopic evaluation of blood smears or amplification of Babesia DNA using a polymerase chain reaction (PCR) assay.
Diagnosis
- For diagnostic confirmation of acute babesiosis, IDSA recommends peripheral blood smear examination or PCR rather than antibody testing (strong recommendation, moderate-quality evidence).
Comment: The diagnosis of babesiosis should be based on epidemiological risk factors and clinical evidence, and confirmed by blood smear examination or PCR.
- For patients with a positive Babesia antibody test, IDSA recommends confirmation with blood smear or PCR before treatment is considered (strong recommendation, moderate-quality evidence).
Comment: A single positive antibody test is not sufficient to establish a diagnosis of babesiosis because Babesia antibodies can persist in blood for a year or more following apparent clearance of infection, with or without treatment.
