A Rare Presentation of Babesia-Associated Splenic Infarction in an Immunocompetent Young Male With Mild Parasitemia.

Babesiosis is a vector-borne protozoal disease primarily transmitted by the Ixodes scapularis tick, though it can also be transmitted through blood transfusions from infected donors. The illness can be asymptomatic or present with mild flu-like symptoms. Still, in severe cases, it can lead to disseminated intravascular coagulation and severe hemolytic anemia, sometimes necessitating management in the intensive care unit. Traditionally, severe babesiosis has been linked to individuals over 50 years old, asplenia, and those who are immunocompromised. Notably, parasitemia levels greater than 10% are also associated with severe disease. However, we report a case of a young, immunocompetent male with severe babesiosis exhibiting severe hemolytic anemia and a rare complication of splenic infarction despite a low level of parasitemia. This case emphasizes that significant clinical complications, like spontaneous splenic infarction, can arise from low parasitemia levels, underscoring the need for heightened awareness of this potential outcome.