Association of ABO groups in malaria infection of variable severity

Literature reports several studies on ABO groups and malaria but a study with an adequate sample size and controls is not available. ABO groups are genetically controlled, hence, large sample size and comparison with population frequency is essential. To determine whether malaria infection with variable severity has correlation with ABO groups.

Blood samples of non-transfused malaria cases were obtained from pathology laboratories and transfused malaria patients' from Blood Bank. The malaria parasites were identified by examination of thick and thin smears. Control (normal population) included 11,303 students.

The ABO group frequency of normal population was 'O' 32.3%, 'A' 22.2%, 'B' 36.7% and 'AB' 8.8%. The overall ABO group distribution in 8028 malaria cases was 'O' 30%, 'A' 24.6%, 'B' 35.5% and 'AB' 8.9%. 'A' group incidence was significantly higher than normal ('A' vs non-'A' = 15, df=1, p <0.001). ABO group frequencies were comparable within Plasmodium falciparum and P. vivax malaria. There was no significant difference in ABO group distribution in malaria patients having severe anemia or among transfused and nontransfused malaria cases. About 32% of P. falciparum cerebral malaria cases and 36% DIC cases were of 'A' group. Compared to 22.2% 'A' group in the population, malaria cases showed preponderance of 'A' group. Because of the small numbers statistical evaluation was not done.

'A' blood group is more susceptible to have malaria infection and risk of cerebral malaria and DIC in malaria is also more in 'A' group individuals.