Plasmodium diversity in non-malaria individuals from the Bioko Island in Equatorial Guinea (West Central-Africa) (original) (raw)
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2016
The archipelago of São Tomé and Principe (STP), West Africa, has suffered the heavy burden of malaria since the 16th century. Until the last decade, when after a successful control program STP has become a low transmission country and one of the few nations with decreases of more than 90% in malaria admission and death rates. We carried out a longitudinal study to determine the genetic structure of STP parasite populations over time and space. Twelve microsatellite loci were genotyped in Plasmodium falciparum samples from two islands collected in 1997, 2000 and 2004. Analysis was performed on proportions of mixed genotype infections, allelic diversity, population differentiation, effective population size and bottleneck effects. We have found high levels of genetic diversity and minimal inter-population genetic differentiation typical of African continental regions with intense and stable malaria transmission. We detected significant differences between the years, with special emphasis for 1997 that showed the highest proportion of samples infected with P. falciparum and the highest mean number of haplotypes per isolate. This study establishes a comprehensive genetic data baseline of a pre-intervention scenario for future studies; taking into account the most recent and successful control intervention on the territory.
Tropical Medicine and International Health, 2001
Background: Malaria is a major public health problem in Cameroon. The study of the genetic diversity within parasite population is essential for understanding the mechanism underlying malaria pathology and to determine parasite clones profile in an infection, for proper malaria control strategies. The objective of this study was to perform a molecular characterization of highly polymorphic genetic markers of Plasmodium falciparum, and to determine allelic distribution with their influencing factors valuable to investigate malaria transmission dynamics in Cameroon. Methods: A total of 350 P. falciparum clinical isolates were characterized by genotyping block 2 of msp-1, block 3 of msp-2, and region II of glurp gene using nested PCR and DNA sequencing between 2012 and 2013. Results: A total of 5 different genotypes with fragment sizes ranging from 597 to 817 bp were recorded for GLURP. Overall, 16 MSP-1 genotypes, including K1, MAD20 and RO33 were identified, ranging from 153 to 335 bp. A peculiarity about this study is the RO33 monomorphic pattern revealed among the Pfmsp-1 allelic type. Again, this study identified 27 different Pfmsp-2 genotypes, ranging from 140 to 568 bp in size, including 15 belonging to the 3D7-type and 12 to the FC27 allelic families. The analysis of the MSP-1 and MSP-2 peptides indicates that the region of the alignment corresponding K1 polymorphism had the highest similarity in the MSP1and MSP2 clade followed by MAD20 with 93% to 100% homology. Therefore, population structure of P. falciparum isolates is identical to that of other areas in Africa, suggesting that vaccine developed with K1 and MAD20 of Pfmsp1 allelic variant could be protective for Africa children but these findings requires further genetic and immunological investigations. The multiplicity of infection (MOI) was significantly higher (P < 0.05) for Pfmsp-2 loci (3.82), as compare with Pfmsp-1 (2.51) and heterozygotes ranged from 0.55 for Pfmsp-1 to 0.96 for Pfmsp-2. Conclusion: High genetic diversity and allelic frequencies in P. falciparum isolates indicate a persisting high level of transmission. This study advocate for an intensification of the malaria control strategies in Cameroon.
Malaria Journal, 2012
Background: Malaria parasite population genetic structure varies among areas of differing endemicity, but this has not been systematically studied across Plasmodium falciparum populations in Africa where most infections occur. Methods: Ten polymorphic P. falciparum microsatellite loci were genotyped in 268 infections from eight locations in four West African countries (Republic of Guinea, Guinea Bissau, The Gambia and Senegal), spanning a highly endemic forested region in the south to a low endemic Sahelian region in the north. Analysis was performed on proportions of mixed genotype infections, genotypic diversity among isolates, multilocus standardized index of association, and inter-population differentiation.
Research Square (Research Square), 2021
Background The assessment of the genetic diversity of Plasmodium falciparum parasites from various malaria transmission settings could help to de ne tailored and dedicated local strategies for malaria control and elimination. To date, this information is scarce in Madagascar. To ll this gap, a study aiming at investigating the genetic diversity of P. falciparum populations in three epidemiological facies (Equatorial, Tropical and Fringes) in Madagascar was conducted. Methods Two hundred sixty-six P. falciparum isolates were obtained from patients with uncomplicated malaria enrolled in clinical drug e cacy studies conducted in health centers at Tsaratanana (Equatorial facies), Antanimbary (Tropical facies) and Anjoma Ramartina (Fringes) in 2013 and 2016. Parasite DNA was extracted from blood samples collected prior antimalarial treatment. Plasmodium species were identi ed by nested-PCR targeting 18S rRNA gene. The genetic pro les of P. falciparum parasites were de ned by assessing the polymorphic regions of the msp-1 and msp-2 genes using allelespeci c nested-PCR. Results A total of 58 alleles were detected for msp-1 (18 alleles) and msp-2 (40 alleles) among P. falciparum samples tested. K1 (62.9%, 139/221) and FC27 (69.5%, 114/164) were the most predominant msp-1 and msp-2 allelic families, although the proportions of the msp-1 and msp-2 alleles varied signi cantly between sites. Polyclonal infections were more frequent in site located in the Equatorial facies (69.8%) compared to sites in the Tropical facies (60.5%) and Fringes (58.1%). Population genetic measures showed that the genetic diversity was similar between sites and the parasite ow within sites was limited. Conclusion This study provides recent information on the genetic diversity of P. falciparum populations in three transmission facies in Madagascar and valuable baseline data to further evaluate the impact of the control measures implemented in Madagascar.
Genes, 2019
Background: Diversity in Plasmodium falciparum poses a major threat to malaria control and elimination interventions. This study utilized 12 polymorphic microsatellite (MS) markers and the Msp2 marker to examine diversity, multiplicity of infection (MOI) as well as the population structure of parasites circulating in two sites separated by about 92 km and with varying malaria transmission intensities within the Greater Accra Region of Ghana. Methods: The diversity and MOI of P. falciparum parasites in 160 non-symptomatic volunteers living in Obom (high malaria transmission intensity) and Asutsuare (low malaria transmission intensity) aged between 8 and 60 years was determined using Msp2 genotyping and microsatellite analysis. Results: The prevalence of asymptomatic P. falciparum carriers as well as the parasite density of infections was significantly higher in Obom than in Asutsuare. Samples from Asutsuare and Obom were 100% and 65% clonal, respectively, by Msp2 genotyping but decreased to 50% and 5%, respectively, when determined by MS analysis. The genetic composition of parasites from Obom and Asutsuare were highly distinct, with parasites from Obom being more diverse than those from Asutsuare. Conclusion: Plasmodium falciparum parasites circulating in Obom are genetically more diverse and distinct from those circulating in Asutsuare. The MOI in samples from both Obom and Asutsuare increased when assessed by MS analysis relative to MSP2 genotyping. The TA40 and TA87 loci are useful markers for estimating MOI in high and low parasite prevalence settings.
Infection, Genetics and Evolution, 2016
The study of genetic diversity of Plasmodium falciparum is necessary to understand the distribution and dynamics of parasite populations. The genetic diversity of P. falciparum merozoite surface protein-1 and 2 has been extensively studied from different parts of world. However, limited data are available from India. This study was aimed to determine the genetic diversity and multiplicity of infection (MOI) of P. falciparum population in Kolkata, West Bengal, India. A total of 80 day-zero blood samples from Kolkata were collected during a therapeutic efficacy study in 2008-2009. DNA was extracted; allelic frequency and diversity were investigated by PCR-genotyping method for msp1 and msp2 gene and fragment sizing was done by Bio-Rad Gel-Doc system using Image Lab (version 4.1) software. P. falciparum msp1 and msp2 markers were highly polymorphic with low allele frequencies. In Kolkata, 27 msp1 different genotypes (including 11of K1, 6 of MAD20 and 10 of Ro33 allelic families) and 30 different msp2 genotypes (of which 17 and 13 belonged to the FC27 and 3D7 allelic families, respectively) were recorded. The majority of these genotypes occurred at a frequency below 10%. The mean MOI for msp1 and msp2 gene were 2.05 and 3.72, respectively. The P. falciparum population of Kolkata was genetically diverse. As the frequencies of most of the msp1 and msp2 alleles were low, the probability of new infection with genotype identical to that in pretreatment infection was very rare. This information will serve as baseline data for evaluation of malaria control interventions as well as for monitoring the parasite population structure.
Pathogens and Global Health, 2019
Asymptomatic carriers of Plasmodium are considered a reservoir of the parasite in humans. Therefore, in order to be effective, new malaria elimination strategies must take these targets into account. The aim of this study was to analyse genetic diversity of Plasmodium falciparum among schoolchildren in three epidemiological areas in Côte d'Ivoire. This was a crosssectional study carried out from May 2015 to April 2016 in a primary school in rural and urban areas of San Pedro, Grand-Bassam and Abengourou, during the rainy season and the dry season. A total of 282 Plasmodium falciparum isolates were genotyped using Nested PCR of Pfmsp1 and Pfmsp2 genes. The overall frequency of K1, Mad20 and RO33 alleles was 81.6%, 53.4% and 57% for Pfmsp1 respectively. For Pfmsp2, this frequency was 84.3% and 72.2% for 3D7 and FC27. K1, Mad20 and FC27 Frequencies were significantly higher in Abengourou compared to other sites. Overall, the frequency of MIs was significantly higher in Abengourou for Pfmsp1 and Pfmsp2. However, Mad20 and RO33 alleles were significantly higher in the rainy season. No significant difference was observed between Pfmsp2 alleles in both seasons. Frequency of the 3D7 allele was significantly higher in symptomatic patients. MIs and COI increased with parasitemia for Pfmsp1and Pfmsp2. The data can be added to that available for monitoring and control of P. falciparum malaria. Further studies combining the entomological inoculation rate and the genetic diversity of P. falciparum will allow us to shed light on our understanding of the epidemiology of this parasite.
Changing the malaria epidemiology will affect the genetic diversity of Plasmodium falciparum. We studied the association between diversity at the merozoite surface protein 2 loci and the severity of disease in childhood malaria in two populations and at different time periods in Ibadan, southwest Nigeria. Population A comprised of 164 children (75 acute uncomplicated malaria (UM), 48 cerebral malaria (CM) and 41 severe malarial anaemia (SMA), while Population B comprised of 225 children (115 UM, 55 CM, 55 SMA). Results showed a high level of genetic diversity and multiplicity of P.falciparum infections in the two populations. Polyinfections were common in the 2 populations but different (93% for PA and 52% for PB), the mean multiplicity of infections was different (3.98 per infected person for Population A and 1.80 for Population B. The presence of polyinfections was significantly lower only in the SMA group in Population A, p=0.007 but significantly lower in the CM, p=0.003 and SMA groups, p=0.000 in Population B. The presence of FC27 and 3D7 alleles was a significant predictor of SMA in Population A but not in Population B. The absence of polyinfections (single infections) was found to be a strong common factor or predictor of severe malaria in the two populations. We conclude that presence of single infections are associated with the development of severe malaria. In addition, malaria control activities have a great impact on the changing parasite population dynamics.