Probing the composition of Plasmodium species contained in malaria infections in the Eastern region of Ghana

Abstract

BackgroundAsymptomatic falciparum and non-falciparum malaria infections are major challenges to malaria control interventions, as they remain a source of continual infection in the community. This becomes even more important as the debate moves towards elimination and eradication. This study sought to quantify the burden of Plasmodium malaria infection in seven communities in the Eastern Region of Ghana.MethodsThe cross-sectional study recruited 729 participants aged 85 years old and below from 7 closely linked communities. Finger pricked blood was used to prepare thick and thin blood smears as well as spot filter paper and an histidine rich protein 2 (HRP2) rapid diagnostic test kit (RDT). Genomic DNA was extracted from the filter paper dry blood spot (DBS) and used in PCR to amplify the Plasmodium 18S rRNA gene using species specific PCR.Results96.6% of the participants were identified as afebrile, with axillary temperatures below 37.5 °C. PCR identified 66% of the participants to harbor malaria parasites, with 9 P. malariae and 7 P. ovale mono-infections accounting for 2.2% and P. falciparum combined with either 36 P. malariae or 25 P. ovale infections, accounting for 13.3%. Parasite prevalence by microscopy (32%) was similar to the RDT positivity rate (33%). False positive RDT results ranged from 64.6% in children aged between 5 and 9 years to 10% in adults aged 20 years and above. No significant differences were observed in falciparum and non-falciparum parasite carriage at the community level, however young adults aged between 15 and 19 years had the highest prevalence (34.8% (16/46)) of P. falciparum and P. malariae parasite carriage whilst children aged between 5 and 9 years had the highest level (11.4% (14/123)) of P. ovale carriage.ConclusionThe high rate of misidentification of non-falciparum parasites and the total absence of detection of P. ovale by microscopy suggests that more sensitive malaria diagnostic tools including molecular assays are required to accurately determine the prevalence of carriers of non-falciparum parasites and low density P. falciparum infections, especially during national surveillance exercises. Additionally, malaria control interventions targeting the non-falciparum species P. malariae and P. ovale parasites are needed.

High prevalence of asymptomatic malaria infections in adults, Ashanti Region, Ghana, 2018

“…With 68%, the prevalence of asymptomatic P. falciparum parasitemia observed in the present study was therefore similar to studies conducted in the rainy season in the Guinea Savannah zone [17,18] and in a rain forest region in Gabon [19]. In a cross-sectional study performed in the Eastern region of Ghana in 2017, the positivity rate among adults 20 years old and above was 14% by RDT and about 55% by PCR [20]. Despite the fact that this study included febrile cases also, the observed prevalence was considerably lower than in the present survey.…”

“…In the cross-sectional study performed in the Eastern region of Ghana, about one out of four malaria cases in individuals aged ≥ 20 years, which were detected by PCR, were also identified by RDT [20].…”

High prevalence of asymptomatic malaria infections in adults, Ashanti Region, Ghana, 2018

“…With 68%, the prevalence of asymptomatic P. falciparum parasitaemia observed in the present study was, therefore, similar to studies conducted in the rainy season in the Guinea Savannah zone [17,18] and in a rain forest region in Gabon [19]. In a cross-sectional study performed in the Eastern region of Ghana in 2017, the positivity rate among adults 20 years old and above was 14% by RDT and about 55% by PCR [20]. Despite the fact that this study included febrile cases also, the observed prevalence was considerably lower than in the present survey.…”

“…Only 4% of parasite carriers were detected by RDT compared to PCR in that study [2]. In the crosssectional study performed in the Eastern region of Ghana, about one out of four malaria cases in individuals aged >20 years, which were detected by PCR, were also identi ed by RDT [20].…”

Contribution of P. falciparum parasites with Pfhrp 2 gene deletions to false negative PfHRP 2 based malaria RDT results in Ghana: A nationwide study of symptomatic malaria patients

“…Samples that were negative by the routinely used CareStart PfHRP 2 RDT ® and positive by microscopy (false negative RDT samples) were sorted out from the total samples collected. Genomic DNA was extracted from the dry blood spots (DBS) using the Chelex extraction method [ 23 ] and from whole blood using the gDNA mini kit (Zymo Research, USA) according to manufacturer’s instructions. Briefly, 100 μl of whole blood was mixed with 400 μl of genomic lysis buffer supplemented with 0.05% β mercaptoethanol in a 1.5 ml tube.…”