Determination of plasmodium falciparum parasites diversity using MSPII family specific allelic primers among symptomatic children aged five years and below in Zambia

Abstract

Introduction: Malaria is still a major public health problem in many tropical and subtropical countries. Therefore effective integrated malaria control strategies are a requirement. However, parasite antigen diversity might be a hurdle in the efficacy of some malaria control strategies like the malaria vaccine against Plasmodium falciparum infection if a full repertoire of variant forms is not incorporated into the vaccine. In addition, malaria rapid diagnostic tests (RDTs) offer great potential for rapid and accurate diagnosis of malaria infections. Parasite genetic diversity of target antigens particularly for PfEiRP2-based RDTs may affect their sensitivity among other factors. Methods: In 2006, a prospective analytical study was conducted to determine the diversity oi Plasmodium falciparum merozoite surface protein 2 (MSP-2) in four sites in Zambia. A nested polymerase chain reaction (PCR) amplification was carried out on two hundred and eighty five dried blood spots with Plasmodium falciparum mono infection using primers for the conserved regions of MSP-2 as well as family specific alleles for the variable regions. PCR-restriction fragment length polymorphism analysis of MSP-2 using a Hinfl digests of each nested PCR product followed by product detection on a 2.0% agarose gel electrophoresis with ethidium bromide was performed to determine the allelic families and genotypes. Results: The study findings show that, there are forty six different genotypes of Plasmodium falciparum commonly found in Zambia, twenty four allelic genotypes belong to the FC27 allelic family and twenty two fi-om the 3D7 allelic family. The study also indicated that Plasmodium falciparum infections carry more than one allelic genotype at each particular time and one infection carried eight different genotypes. Discussion: These findings show that Plasmodium falciparum in Zambia exists in many different allelic genotypes and several patients infected with Plasmodium falciparum carry atleast more than one genotype. Conclusions: This means that the inclusion of all the available genotypes in both the Malaria vaccine and RDTs would be of maximum benefit to the Zambian populations. The multiple Plasmodium falciparum infections will have other implications such as having one genotype sensitive the drug and another resistant therefore this needs to be further explored.