ABO blood groups and malaria related clinical outcome.
The study was undertaken to correlate the blood groups and clinical presentations in malaria patients and to understand the differential host susceptibility in malaria. From October 2007 to September 2008, malaria positive patients' samples were evaluated in this study. Hemoglobin, total leukocyte count, and platelet count of each patient were done on an automated cell counter. After determining the blood groups, malarial species and the severity of clinical course were correlated. A total of 100 patients were included in the study, of which 63 cases were positive for Plasmodium falciparum and 37 cases were positive for P. vivax infection and 11 patients had mixed infection. The results of the blood groups showed 22 - 'A' group, 42 - 'B' group, 35 - 'O' group and 1 was 'AB' group. When the clinical courses between different groups were compared using the following parameters for severe infection--a parasitic load of >10/1000 RBCs, severe anemia with hemoglobin < 6 g%, platelet count of <10,000/mm3, hepato or splenomegaly or clinical signs of severe malaria such as fever >101°F and other organ involvement, it was observed that 'O' group had an advantage over other the groups. The difference in rosetting ability between red blood cells of different 'ABO' blood groups with a diminished rosetting potential in blood group 'O' red blood cells was due to the differential host susceptibility. 'O' group had an advantage over the other three blood groups. Based on literature and the results of this study, the diminished rosetting potential in blood group 'O' red blood cells is suggested as the basis for the differential host susceptibility.