Limited Genetic Diversity and Low Multiplicity of Plasmodium falciparum Infections in Children with Severe Malaria in Lafia, North-central Nigeria

Abstract

Background/Purpose Malaria remains one of the most devastating parasitic diseases in the world. Its pathogenesis is still not clearly understood, although there are indications that several factors between the parasites, the host, and the environment may be involved. In malaria-endemic regions, Plasmodium falciparum infection is characterized by extensive genetic diversity. Describing this diversity provides important information about the local epidemiology of malaria and is crucial for understanding the parasite population structure and virulence, and for evaluating the impact of malaria control measures. The objective of this study was to characterize the genetic diversity of P. falciparum isolates in children with severe malaria by using polymerase chain reaction (PCR) genotyping of the highly polymorphic merozoite surface protein 2 (MSP-2) gene as a molecular marker. Methods One hundred and sixteen children who presented with symptoms of severe malaria and who had microscopically confirmed P. falciparum monoinfection were enrolled in the study after they satisfied the inclusion criteria. Parasite DNA was extracted from the blood spot on to filter paper and analyzed by genotyping the MSP-2 gene using allele-specific nested PCR. Results Twenty-six distinct MSP-2 alleles (13 FC27 alleles and 13 3D7 alleles) were detected in the study population. However, isolates of the 3D7 alleles were predominant in the population (55%), compared to isolates of the FC27 alleles (45%). However, this difference was not statistically significant. The multiplicity of infection (MOI) by P. falciparum was 1.3. Most isolates (66%) were monoclonal infections with one distinguishable clone per infected child. Conclusion The present data suggest a low complexity of P. falciparum infection in isolates of individuals with severe malaria in the study population. The data also show that most infections were monoclonal. Furthermore, no specific genotype was associated with severe malaria in this study.