Levels of Rheumatoid Factor in Plasmodium Falciparum Malaria in Children and Its Association with Gender, Age and Parasite Density

Abstract

Objectives: The rheumatoid factor (RF), like any antibody, may encounter in the body an antigenic specificity. It will then bind to an antigen by cross-reaction or an already formed immune complex. In this context, the RF may impede reactions of diagnosis with immunological principle (antigen-antibody reaction). The rheumatoid factor as well as anti-animal antibodies also reacts with the Fc portion of animal or human IgG of kits of reagents leading to false positive or false negative results. That's the reason why we wanted to have more information about its levels and its association with gender, age and parasite density in children with falciparum malaria. Methodology: It was a prospective study about 130 children of both sexes (M / F: 73/57; mean age: 4.78 ± 3.48 years), suffering from falciparum malaria and aged from 0 to 15 years old. Those children have been included in pediatric services of the University Hospital Center of Cocody and the General Hospital of Kumasi, both, in Abidjan. Venous blood samples were collected on EDTA for blood cells count, parasite densities, and identification of Plasmodium falciparum. The other blood samples collected without EDTA were used to measure Rheumatoid Factor levels. Giemsa-stained thin and thick blood films were analyzed by microscope for plasmodium species and parasite density. Hematological parameters were determined using hematology cell counter (Sysmex KX-21N). Slide agglutination test (RFlatex) was used for qualitative and quantitative detection of Rheumatoid Factor. Statistical analysis was carried out on a computer using Excel 2007 and Statistica 7.1. For all test p-value <0.05 below was considered significant. Results: During falciparum malaria, 30% of children in this study produced RF. The mean level of RF observed in children under 5 years was higher than those whose age was ≥ 5 years but statically not significant (p = 0.07). We also found in children whose age was ≥ 5 years, negative correlation between the level of RF and parasite density, which was stronger than those under 5 years (R =-0.53, p = 0.006 vs R =-0.23 p = 0.013). Most of children secreting Rheumatoid Factor were males (69.23%) and had more risk than females (OR = 3.35). Conclusion: This study showed that 30% of children in falciparum malaria secreted RF. This autoantibody was associated with gender, age and parasite density.