Which patient population is at higher risk for severe Babesia divergens infection?

• A. Immunocompetent adults
• B. Splenectomized patients
• C. Newborns
• D. Pregnant women

Answer: (B)

Splenectomy removes a key line of defense against blood-stage parasites like Babesia. The spleen filters and clears parasitized red blood cells and helps mount the immune response to limit parasite replication. When the spleen is absent, Babesia-infected erythrocytes stay in circulation longer, parasite levels rise higher (parasitemia increases), and complications from hemolysis and organ dysfunction become more likely. Babesia divergens is especially severe in people without a spleen, so splenectomized patients are at the highest risk for severe infection. In contrast, immunocompetent adults, newborns, and pregnant women generally have lower risk of severe disease.