Babesiosis is a malaria-like disease caused by intraerythrocytic protozoa of the genus Babesia

-similar to malaria, the protozoans invade and lyse the red blood cells 

-it is transmitted by ticks, and occasionally through transfusion of blood products 

 -In the United States, infections occur most frequently in the Northeast and upper Midwest

-Babesia trophozoites appear round or ameboid

-The ring form is most common and lacks the central brownish deposit (hemozoin) typical of Plasmodium falciparum trophozoites

Symptoms & Signs 

Babesiosis can be asymptomatic 

-Symptomatic babesiosis may show fatigue, fever, headache, arthralgia, myalgia, nausea, vomiting, abdominal pain, anemia, thrombocytopenia, hepatomegaly, splenomegaly, splenic rupture, hemolysis, jaundice, dark urine 


Blood smear: identification of intraerythrocytic ring forms resembling malaria on a Giemsa- or Wright-stained peripheral blood smear; merozoites often in tetrads (“Maltese cross”) 

Other methods: PCR, indirect immunofluorescent antibody test


-Most patients have a mild illness and recover without therapy

-Similar to malaria, babesiosis requires the use of antiprotozoals

– Two combination therapies are recommended: atovaquone plus azithromycin or quinine plus clindamycin

-in severe disease: exchange transfusion 

Memory Aid: Babesiosis is a malaria like disease caused by a malaria-like organism and treated with malaria-like drugs