Abstract
BackgroundMalaria is still a serious public health problem on Bioko Island (Equatorial Guinea), although the number of annual cases has been greatly reduced since 2004 through the Bioko Island Malaria Control Project (BIMCP). A better understanding of malaria parasite population diversity and transmission dynamics is critical for assessing the effectiveness of malaria control measures. The objective of this study is to investigate the genetic diversity of Plasmodium falciparum populations and multiplicity of infection (MOI) on Bioko Island 7 years after BIMCP.MethodsA total of 181 patients with uncomplicated P. falciparum malaria diagnosed with microscopy were collected from Bioko Island from January 2011 to December 2014. Parasite DNA was extracted using chelex-100 and species were identified using a real-time PCR followed by high-resolution melting. Plasmodium falciparum msp1 and msp2 allelic families were determined using nested PCR.ResultsThree msp1 alleles (K1, MAD20, and RO33) and two msp2 alleles (FC27 and 3D7) were analysed in all samples. In msp1, the MAD20 allelic family was predominant with 96.69% (175/178) followed respectively by the K1 allelic family with 96.07% (171/178) and R033 allelic family with 70.78% (126/178). In msp2, the FC27 allelic family was the most frequently detected with 97.69% (169/173) compared to 3D7 with 72.25% (125/173). Twenty-six different alleles were observed in msp1 with 9 alleles for K1, 9 alleles for MAD20 and 8 alleles for R033. In msp2, 25 individual alleles were detected with 5 alleles for FC27 and 20 alleles for 3D7. The overall MOI was 5.51 with respectively 3.5 and 2.01 for msp1 and msp2. A significant increase in overall MOI was correlated with the age group of the patients (P = 0.026) or parasite densities (P = 0.04).ConclusionsThe present data showed high genetic diversity and MOI values among the P. falciparum population in the study, reflecting both the high endemic level and malaria transmission on Bioko Island. These data provide valuable information for surveillance of P. falciparum infection and for assessing the appropriateness of the current malarial control strategies in the endemic area.
Highlights
Malaria is still a serious public health problem on Bioko Island (Equatorial Guinea), the num‐ ber of annual cases has been greatly reduced since 2004 through the Bioko Island Malaria Control Project (BIMCP)
This study aimed to characterize the genetic diversity of P. falciparum populations and multiplicity of infection (MOI) in malaria parasites isolated from symptomatic patients on Bioko Island 7 years after BIMCP
They were confirmed with P. falciparum monoinfection by polymerase chain reaction (PCR)-HRM [16]
Summary
Malaria is still a serious public health problem on Bioko Island (Equatorial Guinea), the num‐ ber of annual cases has been greatly reduced since 2004 through the Bioko Island Malaria Control Project (BIMCP). For effective control of malaria, many measures have been deployed since 2004 through the Bioko Island Malaria Control Project (BIMCP), including island-wide indoor residual spraying (IRS), long-lasting insecticidetreated nets (LLIN) and artemisinin-based combination therapy (ACT) [2] These control measures have resulted in a substantial decrease in malaria infection on Bioko Island, the disease is still endemic, with populations in some areas remaining at high risk of infection [2, 3]. MSP1 is a 190 kDa surface protein encoded by the msp gene located on chromosome 9 and contains 17 blocks of sequences flanked by conserved regions [5, 6] This protein is a major target of immune responses and is considered a noteworthy candidate for the development of erythrocytic phase malaria vaccines [8, 9]. The alleles of msp are commonly divided into FC27 and 3D7 [11]
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