Absence of erythrocyte sequestration in a case of babesiosis in a splenectomized human patient

Background: The importance of vascular occlusion in the pathogenesis of human haemoprotozoal disease is unresolved. Methods: Giemsa-stained tissue sections from a human case of Babesia microti infection in a splenectomized patient with chronic lymphocytic leukaemia and colon cancer were examined to ascertain the distribution of parasitized erythrocytes within the vascular lumen. Results: No evidence of sequestration was observed. Conclusion: This first report on the vascular location of B. microti in human tissue suggests that severe multi-organ failure due to babesiosis is independent of sequestration of parasitized erythrocytes. A similar pathogenesis may also cause multi-organ failure in other intraerythrocytic protozoal infections, including falciparum malaria.