Genetic diversity of p. falciparum in low and high transmission intensities in Southern Ghana

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June, 2018
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Background: Malaria is a public health challenge that is preventable and can be treated but P. falciparum, the main parasite agent, has survived in the midst of several intervention programmes aimed at combating the infection especially in Sub - Saharan Africa where malaria is endemic. P. falciparum genetic diversity is frequently measured by genotyping the merozoite surface protein (msp 1, 2), however the recent inclusion of Capillary Electrophoresis (CE) based microsatellite markers has enhanced the accuracy of the estimation of multiplicity of infection (MOI) and parasite diversity. This study aims at utilizing 12 unlinked microsatellite markers, msp -2 and Glutamate-Rich Protein (glurp) antigenic marker to determine parasite diversity in different transmission intensities in southern Ghana. METHODS: Whole blood was collected from asymptomatic volunteers living in Obom (hyper-endemic) and Asutuare (holoendemic). Quick DNA kit was used to extract DNA from whole blood samples. The presence of P. falciparum was confirmed by species specific primers Polymerase Chain Reaction (PCR). P. falciparum positive samples were then used for genotyping msp -2 and glurp markers. Clonal Parasite positive samples of msp – 2 were subjected to capillary-based microsatellite genotyping in addition to MSP - 2 genotyping. Results: 44 (55%) and 24 (30%) samples were positive for N5 (3D7) and M5 (FC27) at Obom with average MOI of 1.30. N5 strain was prevalent at both study sites. Only 8(10%) and 4(5%) of N5 and M5 strains respectively were genotyped at Asutuare with an average MOI of 1.0. To compare the prevalence of N5 and M5, a non parametic t-test of p < 0.05 in Obom and p > 0.05 was recorded in Asutuare. For glurp R II region 55 (68.5%) and 70 (87.5%) were genotyped for Obom and Asutuare sites. An average of 35 samples were genotyped using microsatellites markers, average number of alleles for both Obom and Asutuare were 10 and 8 respectively. Genetic diversity of microsatellites was low; He ranged from 0.00 to 0.577 Conclusion: Parasite diversity was high with msp – 2 marker compared to glurp gene, microsatellites had low genetic diversity of the parasites at both sides but the sensitivity and high resolution makes them the markers of choice for genotyping P. falciparum.
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This thesis is presented to the Department of Biochemistry and Biotechnology in partial fulfulment for the award of Master of Philosophy in Biochemistry.
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