Which ONE of the following is true about the pathogenesis of bovine babesiosis? Babesia spp. which cause bovine babesiosis:

• A. Infect red blood cells, which can result in icterus, pale mucous membranes, and hemoglobinuria
• B. Infect white blood cells, which can reslut in swelling of the lymph nodes, fever, and leukopenia
• C. Infect platelets, which can result in widespread blood clotting, disseminated intravascular coagulation, and shock
• D. Infect blood vessels, which can result in fever, chills, trembling, and shock

Answer: (A)

Babesia causes bovine babesiosis by invading red blood cells. This intraerythrocytic infection leads to destruction of RBCs (hemolysis), which in turn produces anemia. The heavy RBC destruction releases hemoglobin into the bloodstream and urine, causing hemoglobinemia and hemoglobinuria, and the increased breakdown of bilirubin from the excess heme can lead to icterus (jaundice). Pale mucous membranes are a clinical sign of the resulting anemia. So the statement that babesiae infect red blood cells and that this can cause icterus, pale mucous membranes, and hemoglobinuria best reflects the primary pathogenesis.

The other ideas don’t fit as the main mechanism: babesiae do not primarily infect white blood cells, platelets, or blood vessel walls, so the listed signs in those options aren’t characteristic features of the typical pathogenesis.