Molecular Identification of Plasmodium Species in Malaria in Zimbabwe by 18S Ribosequencing

Abstract

Background: Malaria remains a major cause of mortality and morbidity in Zimbabwe due to transmission of Plasmodium parasite by the Anopheles mosquitoes. Globally, several species of Plasmodium parasite have been identified, but only P. falciparum, P. ovale, P. vivax, P. malariae and P. knowlesi are known to cause malaria in humans. No studies have previously been done in Zimbabwe to identify the Plasmodium species in malaria using molecular methods. The the aim of this study was to identify circulating Plasmodium species in malaria in Zimbabwe using 18S ribosequencing. Methods: The study was a cross-sectional survey in Zimbabwe from January to May in 2016. Venous blood was collected from malaria-suspected patients at three referral hospitals and subjected to microscopy and/or serology. Total DNA was isolated and Plasmodium species identified by 18S amplification and ribosequencing. Results: A total of 160 patient samples were used in this study. Out of these, 130 were malaria-positive by microscopy and/or serology and 30 were negative. Total genomic DNA was extracted from 100 samples of the patients (80 malaria-positive and 20 malaria-negative samples by microscopy and/or serology). Amplification of the 18S ribosomal RNA gene of Plasmodium was performed on 74 malaria-positive and 6 malaria-negative samples. All the 74 samples showed 18S RNA gene amplification and the 6 negative controls did not show amplification. Only 50 amplicons were selected for sequencing. Ribosequencing and bioinformatics analyses showed that all (100%) the sequences belonged to Plasmodium falciparum. Conclusion: The study was the first to provide molecular evidence of the existence of only P. falciparum in Zimbabwe. However, further studies with bigger sample sizes need to be done to ascertain whether P falciparum is the dominant circulating species in malaria in Zimbabwe.