High IgG1 Malaria Antibodies Level in Children is a Possible Risk Factor of Blackwater Fever: A Case-Control Study

Context: Pathogenesis of acute massive intravascular hemolysis in Blackwater fever is very complex. Mostly, Malaria immunity deficiency in expatriates, Quinine and Plasmodium are incriminated. The possible role of malaria IgG1 antibodies in BWF is not fully elucidated. Objectives: This study aimed to determine the profile of malaria IgG1 for malaria crude antigen in children developing blackwater fever compared to patients with uncomplicated malaria Methods: This case-control study was conducted in 4 medical institutions across Kinshasa. Cases were patients with Blackwater fever (BWF) whereas controls had uncomplicated Plasmodium falciparum malaria (UM). For each case, 2 controls were recruited and were matched for age, sex and the area of residence. Malaria IgG1 were assessed by standard ELISA and absorbance measured in an automated plate reader. Results: The majority of BWF cases (81.4%) were above 5 years old while only 18.6% were aged below 5 (OR: 1.33; 0.53-3.32). The level of malaria IgG antibodies in BWF children were significantly higher compared to uncomplicated malaria (p=0.002). Quinine was used by 95.3% of the BWF cases ([OR: 50.19 (10.75-234.42)] p<0.001) versus in uncomplicated malaria. There was no linear correlation between the age of patients and the logarithm of antibodies. R2 is totally null (p=0.335). Conclusion: Malaria IgG1 antibodies is significantly elevated in children with BWF and could trigger the occurrence of BWF. The absence of correlation with age suggests that BWF could not be age dependent.