Nationwide molecular surveillance of three\xa0Plasmodium\xa0species harboured by symptomatic malaria patients living in Ghana

Linda E Amoah,Keziah L Malm,Benjamin Abuaku,Nana Peprah,Alexander Asamoah,Abena Busayo,George Asumah,Dorcas Bredu,Sherik-Fa Anang,Kwame K Asare,Donu Dickson

doi:10.1186/s13071-022-05153-6

Linda E Amoah, Keziah L Malm + Show 9 more

Open Access

https://doi.org/10.1186/s13071-022-05153-6

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Abstract

BackgroundClinical presentations of malaria in Ghana are primarily caused by infections containing microscopic densities of Plasmodium falciparum, with a minor contribution from Plasmodium malariae and Plasmodium ovale. However, infections containing submicroscopic parasite densities can result in clinical disease. In this study, we used PCR to determine the prevalence of three human malaria parasite species harboured by suspected malaria patients attending healthcare facilities across the country.MethodsArchived dried blood spots on filter paper that had been prepared from whole blood collected from 5260 patients with suspected malaria attending healthcare facilities across the country in 2018 were used as experimental material. Plasmodium species-specific PCR was performed on DNA extracted from the dried blood spots. Demographic data and microscopy data for the subset of samples tested were available from the original study on these specimens.ResultsThe overall frequency of P. falciparum, P. malariae and P. ovale detected by PCR was 74.9, 1.4 and 0.9%, respectively. Of the suspected symptomatic P. falciparum malaria cases, 33.5% contained submicroscopic densities of parasites. For all regions, molecular diagnosis of P. falciparum, P. malariae and P. ovale was significantly higher than diagnosis using microscopy: up to 98.7% (75/76) of P. malariae and 97.8% (45/46) of P. ovale infections detected by PCR were missed by microscopy.ConclusionPlasmodium malariae and P. ovale contributed to clinical malaria infections, with children aged between 5 and 15 years harbouring a higher frequency of P. falciparum and P. ovale, whilst P. malariae was more predominant in individuals aged between 10 and 20 years. More sensitive point-of-care tools are needed to detect the presence of low-density (submicroscopic) Plasmodium infections, which may be responsible for symptomatic infections.Graphical

Highlights

Clinical presentations of malaria in Ghana are primarily caused by infections containing microscopic densities of Plasmodium falciparum, with a minor contribution from Plasmodium malariae and Plasmodium ovale
Regional distribution of Plasmodium species among study subjects Microscopy The frequency of P. falciparum detected by microscopy in the subset of samples used in this study was 2284/4937 (46.3%), with the highest frequency identified in the Ashanti region 412/476 (86.6%) and the lowest detected in the Eastern region 41/292 (14.0%) (Table 1)
The results of this study showed that the frequencies of P. malariae and P. ovale causing symptomatic disease are very similar to those reported previously from other countries in sub-Saharan Africa, where 0.2–4.8% P. ovale malaria cases and 0.3–2.8% of P. malar‐ iae malaria cases were associated with symptomatic malaria [14, 28,29,30,31,32,33]

Summary

Introduction

Clinical presentations of malaria in Ghana are primarily caused by infections containing microscopic densities of Plasmodium falciparum, with a minor contribution from Plasmodium malariae and Plasmodium ovale. Infections containing submicroscopic parasite densities can result in clinical disease. Plasmodium species that infect humans include Plas‐ modium malariae, Plasmodium ovale, Plasmodium vivax, Plasmodium knowlesi, and Plasmodium falcipa‐ rum; of these P. falciparum is responsible for most of the malaria cases in Ghana [1, 2]. Infections with all human Plasmodium parasites can result in various presentations of disease, with the uncomplicated and asymptomatic presentations being the most predominant manifestations of parasite infection. Microscopy can provide an estimate of malaria parasite density from thick blood smears and information on the various parasite species present in an infection from a thin blood smear. The downside to microscopy is that it requires experts to prepare and stain the blood smear as well as electricity and a microscope, in addition to an expert malaria microscopist to read and grade the smear

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