Genetic diversity of Plasmodium falciparum infection among children with uncomplicated malaria living in Pointe-Noire, Republic of Congo

Abstract

Introduction Molecular characterization of malaria parasites from different localities is important to improve understanding of acquisition of natural immunity to Plasmodium falciparum , to assist in identifying the most appropriate strategies for control and to evaluate the impact of control interventions. This study aimed to determine the genetic diversity and the multiplicity of infection in Plasmodium falciparum isolates from Pointe-Noire, Republic of Congo. Methods Plasmodium falciparum isolates were collected from 71 children with uncomplicated malaria; enrolled into the study for evaluating the therapeutic efficacy of artemether-lumefantrine combination. Both msp-1 and msp-2 genes were genotyped. Results From 296 distinct fragments detected, 13 msp-1 and 27 msp-2 different alleles were identified. For msp-1 , RO33 family was poorly polymorphic. The K1 family has shown the trend of predominance (41%), followed by Mad20 (35%). Comparatively to msp-2 , 49.6% and 48.8% fragments belonged to 3D7 and FC27 respectively. Taking together msp-1 and msp-2 genes, the overall multiplicity of infection has been increased to 2.64 and 86% harbored more than one parasite genotype. Parasite density was not influenced by age as well as the multiplicity of infection which was not influenced neither by age nor by parasite density. Conclusion Genetic diversity of Plasmodium falciparum in isolates from patients with uncomplicated malaria in Pointe-Noire is high and consisted mainly of multiple clones. The overall multiplicity of infection has been largely increased when considering msp-1 and msp-2 genes together. With the changes in malaria epidemiology, the use of both msp-1 and msp-2 genes in the characterization of Plasmodium falciparum infection is recommended.

The diversity of Plasmodium falciparum isolates from asymptomatic and symptomatic school-age children in Kinshasa Province, Democratic Republic of Congo

“…The pfmsp2 gene was found to be genetically more diverse than the pfmsp1 gene in the study areas, in support of the findings of the majority of studies conducted in Africa [ 15 , 33 – 35 , 59 ]. This confirms that in many malaria-endemic African countries, polymorphic pfmsp2 allelic families may be circulating at higher frequencies than those for pfmsp1 .…”

“…This study showed a generally lower MOI than has been previously reported in the DRC, Cameroon, and Republic of Congo [32,34,35]. Conversely, this study showed a higher MOI than that in reports from Grande Comore Island, Côte d'Ivoire, and Gabon [59][60][61][62][63], whereas it was similar to an MOI reported in the Republic of Congo by Mayengue et al [33].…”

“…For instance, some reports from the DRC and other countries showed a positive correlation of the MOI with malaria recrudescence [32] and parasitaemia level [19,33,52] and a negative correlation between the MOI and acquired immunity level [64]. Conversely, other studies did not find a significant association of the MOI with either parasitaemia or clinical status [35,63]. However, the studies that established the relationship of the MOI with either parasitaemia or clinical status did not associate them (parasitaemia and clinical status) to minimize confounding factors.…”

“…Thus, pfmsp1 block 2 and pfmsp2 block 3 may constitute good indicators for measuring malaria transmission intensity and malaria control interventions. The pfmsp2 gene was previously found to be more genetically diverse than pfmsp1 in the Democratic Republic of Congo (DRC) [32] and the Republic of Congo and Cameroon [33][34][35]. MSP2 is considered to be a candidate marker for evaluating parasite virulence [27,32].…”