Geographic Regions with High Endemicity

Geographic Regions with Low Endemicity

Other Geographic Regions

Risk Factors


Routes of Transmission

  • Tick Bite (see Tick-Borne Illnesses, [[Tick-Borne Illnesses]]): main route of transmission
  • Transmission Via Blood Transfusion (see Packed Red Blood Cells, [[Packed Red Blood Cells]]): less common
    • Platelet Transfusion (see Platelet Transfusion, [[Platelet Transfusion]]): few cases have been reported (platelets were contaminated with red blood cells)
  • Transplacental Transmission: case reports

Babesia Species

Babesia Microti

  • Geography
    • Northeast US
    • Upper Midwest US
  • Tick Vector: Ixodes Scapularis (see Ixodes Ticks, [[Ixodes Ticks]])
    • Reservoir: white-tailed deer and mice
    • Incubation Period: 5-33 days

Babesia Divergens

  • Geography
    • Europe
  • Tick Vector: Ixodes Ricinus (this is also the presumed tick vector responsible for European cases of Human Granulocytic Anaplasmosis, HGA) (see Anaplasmosis)
    • Reservoir: cattle

Other Babesia Species

  • Babesia Duncani
    • Sporadic Outbreaks Along the Pacific Coast of the US (from California to Washington)
  • Babesia Divergens-Like Organisms: Midwestern US
    • Midwest US (Kentucky, Missouri) and Northwest US (Washington)
  • Babesia Divergens-Like Organisms: Canary Islands
  • Babesia Venatorum: Europe
  • Babesia Venatorum: Northeastern China
  • Babesia Microti-Like Organisms: Japan
  • Babesia KO1: South Korea


Complete Blood Count (CBC) (see Complete Blood Count, [[Complete Blood Count]])

Blood Culture (see Blood Culture, [[Blood Culture]])

Peripheral (Thin) Blood Smear (see Peripheral Blood Smear, [[Peripheral Blood Smear]])

PCR for Babesia Microti DNA


Clinical Manifestations

General Comments

Constitutional Manifestations

Gastrointestinal Manifestations

Hematologic Manifestations

Neurologic Manifestations

Rheumatologic Manifestations


General Comments

Clindamycin + Quinine (see Clindamycin, [[Clindamycin]] and Quinine, [[Quinine]])

Atovaquone + Azithromycin (see Atovaquone, [[Atovaquone]] and Azithromycin, [[Azithromycin]])

Exchange Transfusion (see Exchange Transfusion, [[Exchange Transfusion]])