Genetic diversity of the msp-1, msp-2, and glurp genes of Plasmodium falciparum isolates in Northwest Ethiopia

Genetic diversity of glutamate-rich protein (GLURP) in Plasmodium falciparum isolates from school-age children in Kinshasa, DRC

Malaria infections in school-age children further make it difficult to control the disease's spread. Moreover, the genetic diversity of glutamate-rich protein, potentially a candidate for vaccine development, has not yet been investigated in the Democratic Republic of Congo. Therefore, we aimed to assess the genetic diversity of the immunodominant C-terminal repetitive region (R2) of Plasmodium falciparum glutamate-rich protein gene (pfglurp) among school-age children living in Kinshasa, DRC. We conducted nested PCR targeting R2 of pfglurp and the amplicon were directly sequenced. We summarized the prevalence of mutations of bases and amino acids and indicated the amino acid repeat sequence in the R2 region by the unit code. We then statistically analyzed whether there was a relationship between the number of mutations in the pfglurp gene and attributes. In 221 samples, haplotype 1 was the most common (n = 137, 61.99%), with the same sequence as the 3D7 strain. Regarding the number of base mutations, it was higher in urban areas than rural areas (p = 0.0363). When genetic neutrality was tested using data from 171 samples of the single strain, Tajima's D was -1.857 (p = 0.0059). In addition, FST as the genetic distance between all attributes was very small and no significant difference was observed. This study clarified the genetic mutation status and relevant patient attributes among School-age children in the DRC. We found that urban areas are more likely to harbour pfglurp mutations. Future research needs to clarify the reason and mechanism involved.

Plasmodium falciparum genetic diversity and multiplicity of infection based on msp-1, msp-2, glurp and microsatellite genetic markers in sub-Saharan Africa: a systematic review and meta-analysis

BACKGROUND

In sub-Saharan Africa (SSA), Plasmodium falciparum causes most of the malaria cases. Despite its crucial roles in disease severity and drug resistance, comprehensive data on Plasmodium falciparum genetic diversity and multiplicity of infection (MOI) are sparse in SSA. This study summarizes available information on genetic diversity and MOI, focusing on key markers (msp-1, msp-2, glurp, and microsatellites). The systematic review aimed to evaluate their influence on malaria transmission dynamics and offer insights for enhancing malaria control measures in SSA.

METHODS

The review was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Two reviewers conducted article screening, assessed the risk of bias (RoB), and performed data abstraction. Meta-analysis was performed using the random-effects model in STATA version 17.

RESULTS

The review included 52 articles: 39 cross-sectional studies and 13 Randomized Controlled Trial (RCT)/cohort studies, involving 11,640 genotyped parasite isolates from 23 SSA countries. The overall pooled mean expected heterozygosity was 0.65 (95% CI: 0.51-0.78). Regionally, values varied: East (0.58), Central (0.84), Southern (0.74), and West Africa (0.69). Overall pooled allele frequencies of msp-1 alleles K1, MAD20, and RO33 were 61%, 44%, and 40%, respectively, while msp-2 I/C 3D7 and FC27 alleles were 61% and 55%. Central Africa reported higher frequencies (K1: 74%, MAD20: 51%, RO33: 48%) than East Africa (K1: 46%, MAD20: 42%, RO33: 31%). For msp-2, East Africa had 60% and 55% for I/C 3D7 and FC27 alleles, while West Africa had 62% and 50%, respectively. The pooled allele frequency for glurp was 66%. The overall pooled mean MOI was 2.09 (95% CI: 1.88-2.30), with regional variations: East (2.05), Central (2.37), Southern (2.16), and West Africa (1.96). The overall prevalence of polyclonal Plasmodium falciparum infections was 63% (95% CI: 56-70), with regional prevalences as follows: East (62%), West (61%), Central (65%), and South Africa (71%).

CONCLUSION

The study shows substantial regional variation in Plasmodium falciparum parasite genetic diversity and MOI in SSA. These findings suggest a need for malaria control strategies and surveillance efforts considering regional-specific factors underlying Plasmodium falciparum infection.

A Comparative Study of Genetic Diversity and Multiplicity of Infection in Uncomplicated Plasmodium falciparum Infections in Selected Regions of Pre-Elimination and High Transmission Settings Using MSP1 and MSP2 Genes

BACKGROUND

Understanding the genetic structure of P. falciparum population in different regions is pivotal to malaria elimination. Genetic diversity and the multiplicity of infection are indicators used for measuring malaria endemicity across different transmission settings. Therefore, this study characterized P. falciparum infections from selected areas constituting pre-elimination and high transmission settings in South Africa and Nigeria, respectively.

METHODS

Parasite genomic DNA was extracted from 129 participants with uncomplicated P. falciparum infections. Isolates were collected from 78 participants in South Africa (southern Africa) and 51 in Nigeria (western Africa). Allelic typing of the msp1 and msp2 genes was carried out using nested PCR.

RESULTS

In msp1, the K1 allele (39.7%) was the most common allele among the South African isolates, while the RO33 allele (90.2%) was the most common allele among the Nigerian isolates. In the msp2 gene, FC27 and IC3D7 showed almost the same percentage distribution (44.9% and 43.6%) in the South African isolates, whereas FC27 had the highest percentage distribution (60.8%) in the Nigerian isolates. The msp2 gene showed highly distinctive genotypes, indicating high genetic diversity in the South African isolates, whereas msp1 showed high genetic diversity in the Nigerian isolates. The RO33 allelic family displayed an inverse relationship with participants' age in the Nigerian isolates. The overall multiplicity of infection (MOI) was significantly higher in Nigeria (2.87) than in South Africa (2.44) (p < 0.000 *). In addition, heterozygosity was moderately higher in South Africa (1.46) than in Nigeria (1.13).

CONCLUSIONS

The high genetic diversity and MOI in P. falciparum that were observed in this study could provide surveillance data, on the basis of which appropriate control strategies should be adopted.

High Prevalence of Polyclonal Plasmodium falciparum Infections and Association with Poor IgG Antibody Responses in a Hyper-Endemic Area in Cameroon

Malaria remains a major public health problem worldwide, with eradication efforts thwarted by drug and insecticide resistance and the lack of a broadly effective malaria vaccine. In continuously exposed communities, polyclonal infections are thought to reduce the risk of severe disease and promote the establishment of asymptomatic infections. We sought to investigate the relationship between the complexity of P. falciparum infection and underlying host adaptive immune responses in an area with a high prevalence of asymptomatic parasitaemia in Cameroon. A cross-sectional study of 353 individuals aged 2 to 86 years (median age = 16 years) was conducted in five villages in the Centre Region of Cameroon. Plasmodium falciparum infection was detected by multiplex nested PCR in 316 samples, of which 278 were successfully genotyped. Of these, 60.1% (167/278) were polyclonal infections, the majority (80.2%) of which were from asymptomatic carriers. Host-parasite factors associated with polyclonal infection in the study population included peripheral blood parasite density, participant age and village of residence. The number of parasite clones per infected sample increased significantly with parasite density (r = 0.3912, p < 0.0001) but decreased with participant age (r = -0.4860, p < 0.0001). Parasitaemia and the number of clones per sample correlated negatively with total plasma levels of IgG antibodies to three highly reactive P. falciparum antigens (MSP-1p19, MSP-3 and EBA175) and two soluble antigen extracts (merozoite and mixed stage antigens). Surprisingly, we observed no association between the frequency of polyclonal infection and susceptibility to clinical disease as assessed by the recent occurrence of malarial symptoms or duration since the previous fever episode. Overall, the data indicate that in areas with the high perennial transmission of P. falciparum, parasite polyclonality is dependent on underlying host antibody responses, with the majority of polyclonal infections occurring in persons with low levels of protective anti-plasmodial antibodies.

Comparative study of Plasmodium falciparum msp-1 and msp-2 Genetic Diversity in Isolates from Rural and Urban Areas in the South of Brazzaville, Republic of Congo

Polymorphisms in the genes encoding the merozoite surface proteins msp-1 and msp-2 are widely used markers for characterizing the genetic diversity of Plasmodium falciparum. This study aimed to compare the genetic diversity of circulating parasite strains in rural and urban settings in the Republic of Congo after the introduction of artemisinin-based combination therapy (ACT) in 2006. A cross-sectional survey was conducted from March to September 2021 in rural and urban areas close to Brazzaville, during which Plasmodium infection was detected using microscopy (and nested-PCR for submicroscopic infection). The genes coding for merozoite proteins-1 and -2 were genotyped by allele-specific nested PCR. Totals of 397 (72.4%) and 151 (27.6%) P. falciparum isolates were collected in rural and urban areas, respectively. The K1/msp-1 and FC27/msp-2 allelic families were predominant both in rural (39% and 64%, respectively) and urban (45.4% and 54.5% respectively) areas. The multiplicity of infection (MOI) was higher (p = 0.0006) in rural areas (2.9) compared to urban settings (2.4). The rainy season and the positive microscopic infection were associated with an increase in MOI. These findings reveal a higher P. falciparum genetic diversity and MOI in the rural setting of the Republic of Congo, which is influenced by the season and the participant clinical status.

The diversity of Plasmodium falciparum isolates from asymptomatic and symptomatic school-age children in Kinshasa Province, Democratic Republic of Congo

BACKGROUND

Understanding Plasmodium falciparum population diversity and transmission dynamics provides information on the intensity of malaria transmission, which is needed for assessing malaria control interventions. This study aimed to determine P. falciparum allelic diversity and multiplicity of infection (MOI) among asymptomatic and symptomatic school-age children in Kinshasa Province, Democratic Republic of Congo (DRC).

METHODS

A total of 438 DNA samples (248 asymptomatic and 190 symptomatic) were characterized by nested PCR and genotyping the polymorphic regions of pfmsp1 block 2 and pfmsp2 block 3.

RESULTS

Nine allele types were observed in pfmsp1 block2. The K1-type allele was predominant with 78% (229/293) prevalence, followed by the MAD20-type allele (52%, 152/293) and RO33-type allele (44%, 129/293). Twelve alleles were detected in pfmsp2, and the 3D7-type allele was the most frequent with 84% (256/304) prevalence, followed by the FC27-type allele (66%, 201/304). Polyclonal infections were detected in 63% (95% CI 56, 69) of the samples, and the MOI (SD) was 1.99 (0.97) in P. falciparum single-species infections. MOIs significantly increased in P. falciparum isolates from symptomatic parasite carriers compared with asymptomatic carriers (2.24 versus 1.69, adjusted b: 0.36, (95% CI 0.01, 0.72), p = 0.046) and parasitaemia > 10,000 parasites/µL compared to parasitaemia < 5000 parasites/µL (2.68 versus 1.63, adjusted b: 0.89, (95% CI 0.46, 1.25), p < 0.001).

CONCLUSION

This survey showed low allelic diversity and MOI of P. falciparum, which reflects a moderate intensity of malaria transmission in the study areas. MOIs were more likely to be common in symptomatic infections and increased with the parasitaemia level. Further studies in different transmission zones are needed to understand the epidemiology and parasite complexity in the DRC.

Low genetic diversity of Plasmodium falciparum merozoite surface protein 1 and 2 and multiplicity of infections in western Ethiopia following effective malaria interventions

BACKGROUND

Genetic diversity of malaria parasites can inform the intensity of transmission and poses a major threat to malaria control and elimination interventions. Characterization of the genetic diversity would provide essential information about the ongoing control efforts. This study aimed to explore allelic polymorphism of merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) to determine the genetic diversity and multiplicity of Plasmodium falciparum infections circulating in high and low transmission sites in western Ethiopia.

METHODS

Parasite genomic DNA was extracted from a total of 225 dried blood spots collected from confirmed uncomplicated P. falciparum malaria-infected patients in western Ethiopia. Of these, 72.4% (163/225) and 27.6% (62/225) of the samples were collected in high and low transmission areas, respectively. Polymorphic msp1 and msp2 genes were used to explore the genetic diversity and multiplicity of falciparum malaria infections. Genotyping of msp1 was successful in 86.5% (141/163) and 88.7% (55/62) samples collected from high and low transmission areas, respectively. Genotyping of msp2 was carried out among 85.3% (139/163) and 96.8% (60/62) of the samples collected in high and low transmission sites, respectively. Plasmodium falciparum msp1 and msp2 genes were amplified by nested PCR and the PCR products were analysed by QIAxcel ScreenGel Software. A P-value of less or equal to 0.05 was considered significant.

RESULTS

High prevalence of falciparum malaria was identified in children less than 15 years as compared with those  ≥ 15 years old (AOR = 2.438, P = 0.005). The three allelic families of msp1 (K1, MAD20, and RO33) and the two allelic families of msp2 (FC27 and 3D7), were observed in samples collected in high and low transmission areas. However, MAD 20 and FC 27 alleles were the predominant allelic families in both settings. Plasmodium falciparum isolates circulating in western Ethiopia had low genetic diversity and mean MOI. No difference in mean MOI between high transmission sites (mean MOI 1.104) compared with low transmission area (mean MOI 1.08) (p > 0.05). The expected heterozygosity of msp1 was slightly higher in isolates collected from high transmission sites (He = 0.17) than in those isolates from low transmission (He = 0.12). However, the heterozygosity of msp2 was not different in both settings (Pfmsp2: 0.04 in high transmission; pfmsp2: 0.03 in low transmission).

CONCLUSION

Plasmodium falciparum from clinical malaria cases in western Ethiopia has low genetic diversity and multiplicity of infection irrespective of the intensity of transmission at the site of sampling. These may be signaling the effectiveness of malaria control strategies in Ethiopia; although further studies are required to determine how specific intervention strategies and other parameters that drive the pattern.

Genetic Diversity of Merozoite Surface Protein-1 and -2 Genes in Plasmodium falciparum Isolates among Asymptomatic Population in Boset and Badewacho Districts, Southern Ethiopia

Background

The genetic variation of Plasmodium falciparum has been studied to assess local malaria transmission genetic profile using evidence-based intervention measures. However, there are no known previous reports of P. falciparum polymorphism in Badewacho and Boset districts, Southern Ethiopia. The purpose of this study was to determine the genetic diversity of the merozoite surface protein-1 and -2 (msp-1 and msp-2) allelic families in P. falciparum isolates from an asymptomatic populations.

Methods

This study was conducted from finger-prick blood samples spotted on 3 mm Whatman filter paper collected during a community-based cross-sectional study. Nested polymerase chain reaction amplification was used to type the allelic variants of msp-1 and msp-2.

Results

From 669 asymptomatic study participants, a total of 50 samples positive for P. falciparum were included for molecular analysis. Of 50 positive samples, 43 P. falciparum isolates were successfully amplified for the msp-1 and msp-2 allelic families. A total of twelve different allele sizes (75-250 bp) were identified within the three allelic families of msp-1, whereas ten different allele sizes (250-500 bp) were detected within the two allelic families of msp-2. MAD20 had a higher allelic proportion, 65% among allelic families of msp-1, whereas the 3D7 allelic family 90.7% was higher in msp-2. A slightly higher frequency of polyclonal infection 53.5% was found in msp-2 allelic family, whereas a low proportion polyclonal infection 46.5% was found in msp-1 allelic family. The overall mean multiplicity of infection (MOI) for msp-1 and msp-2 was identical (MOI = 1.56). Correspondingly, the expected heterozygosity (He) value for msp-1 (He = 0.23) and msp-2 (He = 0.22) was almost similar.

Conclusions

The findings of this study revealed low genetic diversity of the msp-1 and msp-2 allelic families in P. falciparum isolates. However, continued monitoring status of the local genetic diversity profile in the P. falciparum population is required to support current malaria control and elimination strategies.

Therapeutic efficacies of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum and chloroquine and dihydroartemisinin-piperaquine for uncomplicated Plasmodium vivax infection in Ethiopia

BACKGROUND

Routine monitoring of anti-malarial drugs is recommended for early detection of drug resistance and to inform national malaria treatment guidelines. In Ethiopia, the national treatment guidelines employ a species-specific approach. Artemether-lumefantrine (AL) and chloroquine (CQ) are the first-line schizonticidal treatments for Plasmodium falciparum and Plasmodium vivax, respectively. The National Malaria Control and Elimination Programme in Ethiopia is considering dihydroartemisinin-piperaquine (DHA/PPQ) as an alternative regimen for P. falciparum and P. vivax.

METHODS

The study assessed the clinical and parasitological efficacy of AL, CQ, and DHA/PPQ in four arms. Patients over 6 months and less than 18 years of age with uncomplicated malaria mono-infection were recruited and allocated to AL against P. falciparum and CQ against P. vivax. Patients 18 years or older with uncomplicated malaria mono-infection were recruited and randomized to AL or dihydroartemisinin-piperaquine (DHA/PPQ) against P. falciparum and CQ or DHA/PPQ for P. vivax. Patients were followed up for 28 (for CQ and AL) or 42 days (for DHA/PPQ) according to the WHO recommendations. Polymerase chain reaction (PCR)-corrected and uncorrected estimates were analysed by Kaplan Meier survival analysis and per protocol methods.

RESULTS

A total of 379 patients were enroled in four arms (n = 106, AL-P. falciparum; n = 75, DHA/PPQ- P. falciparum; n = 142, CQ-P. vivax; n = 56, DHA/PPQ-P. vivax). High PCR-corrected adequate clinical and parasitological response (ACPR) rates were observed at the primary end points of 28 days for AL and CQ and 42 days for DHA/PPQ. ACPR rates were 100% in AL-Pf (95% CI: 96-100), 98% in CQ-P. vivax (95% CI: 95-100) at 28 days, and 100% in the DHA/PPQ arms for both P. falciparum and P. vivax at 42 days. For secondary endpoints, by day three 99% of AL-P. falciparum patients (n = 101) cleared parasites and 100% were afebrile. For all other arms, 100% of patients cleared parasites and were afebrile by day three. No serious adverse events were reported.

CONCLUSION

This study demonstrated high therapeutic efficacy for the anti-malarial drugs currently used by the malaria control programme in Ethiopia and provides information on the efficacy of DHA/PPQ for the treatment of P. falciparum and P. vivax as an alternative option.

Plasmodium falciparum Merozoite Surface Proteins Polymorphisms and Treatment Outcomes among Patients with Uncomplicated Malaria in Mwanza, Tanzania

Background. The severity of malaria infection depends on the host, parasite and environmental factors. Merozoite surface protein (msp) diversity determines transmission dynamics, P. falciparum immunity evasion, and pathogenesis or virulence. There is limited updated information on P. falciparum msp polymorphisms and their impact on artemether-lumefantrine treatment outcomes in Tanzania. Therefore, this study is aimed at examining msp genetic diversity and multiplicity of infection (MOI) among P. falciparum malaria patients. The influence of MOI on peripheral parasite clearance and adequate clinical and parasitological response (ACPR) was also assessed. Methods. Parasite DNA was extracted from dried blood spots according to the manufacture’s protocol. Primary and nested PCR were performed. The PCR products for both the block 2 region of msp1 and the block 3 regions of msp2 genes and their specific allelic families were visualized on a 2.5% agarose gel. Results. The majority of the isolates, 58/102 (58.8%) for msp1 and 69/115 (60.1%) for msp2, harboured more than one parasite genotypes. For the msp1 gene, K1 was the predominant allele observed (75.64%), whereas RO33 occurred at the lowest frequency (43.6%). For the msp2 gene, the 3D7 allele was observed at a higher frequency (81.7%) than the FC27 allele (76.9%). The MOIs were 2.44 for msp1 and 2.27 for msp2 ( $p=0.669$ ). A significant correlation between age and multiplicity of infection (MOI) for msp1 or MOI for msp2 was not established in this study (rho = 0.074, $p=0.521$ and rho = −0.129, $p=0.261$ , respectively). Similarly, there was no positive correlation between parasite density at day 1 and MOI for both msp1 (rho = 0.113, $p=0.244$ ) and msp2 (rho = 0.043, $p=0.712$ ). The association between MOI and ACPR was not observed for either msp1 or mps2 ( $p=0.776$ and 0.296, respectively). Conclusions. This study reports high polyclonal infections, MOI and allelic frequencies for both msp1 and msp2. There was a lack of correlation between MOI and ACPR. However, a borderline significant correlation was observed between day 2 parasitaemia and MOI.

Temporal dynamics of Plasmodium falciparum population in Metehara, east-central Ethiopia

Background

Plasmodium falciparum is the most serious, genetically most complex and fastest-evolving malaria parasite. Information on genetic diversity of this parasite would guide policy decision and malaria elimination endeavors. This study explored the temporal dynamics of P. falciparum population in two time points in Metehara, east-central Ethiopia.

Methods

The participants were quantitative real-time polymerase chain reaction-confirmed patients who were recruited for uncomplicated falciparum malaria therapeutic efficacy test in 2015 and 2019. Dry blood spot samples were analysed by the nested PCR to genotype P. falciparum merozoite surface protein (msp1, msp2) and glutamate-rich protein (glurp) genes.

Results

While msp1, msp2 and glurp genotypes were successfully detected in 26(89.7%), 24(82.8%) and 14(48.3%) of 2015 samples (n = 29); the respective figures for 2019 (n = 41) were 31(68.3%), 39(95.1%), 25(61.0%). In 2015, the frequencies of K1, MAD20 and RO33 allelic families of msp1, and FC27 and IC/3D7 of msp2 were 19(73.1%), 8(30.6%), 14(53.8%), 21(87.5%), 12(50.5%); and in 2019 it was 15(48.4%), 19(61.3%), 15(48.4%), 30(76.9%), 27(69.2%) respectively. MAD20 has shown dominance over both K1 and RO33 in 2019 compared to the proportion in 2015. Similarly, although FC27 remained dominant, there was shifting trend in the frequency of IC/3D7 from 50.5% in 2015 to 69.2% in 2019. The multiplicity of infection (MOI) and expected heterozygosity index (He) in 2015 and 2019 were respectively [1.43 ± 0.84] and [1.15 ± 0.91], 0.3 and 0.03 for msp1. However, there was no significant association between MOI and age or parasitaemia in both time points.

Conclusion

The lower genetic diversity in P. falciparum population in the two time points and overall declining trend as demonstrated by the lower MOI and He may suggest better progress in malaria control in Metehara. But, the driving force and selective advantage of switching to MAD20 dominance over the other two msp1 allelic families, and the dynamics within msp2 alleles needs further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04277-5.

Comparative Assessment of Diagnostic Performance of Cytochrome Oxidase Multiplex PCR and 18S rRNA Nested PCR

Malaria elimination and control require prompt and accurate diagnosis for treatment plan. Since microscopy and rapid diagnostic test (RDT) are not sensitive particularly for diagnosing low parasitemia, highly sensitive diagnostic tools are required for accurate treatment. Molecular diagnosis of malaria is commonly carried out by nested polymerase chain reaction (PCR) targeting 18S rRNA gene, while this technique involves long turnaround time and multiple steps leading to false positive results. To overcome these drawbacks, we compared highly sensitive cytochrome oxidase gene-based single-step multiplex reaction with 18S rRNA nested PCR. Cytochrome oxidase (cox) genes of P. falciparum (cox-III) and P. vivax (cox-I) were compared with 18S rRNA gene nested PCR and microscopy. Cox gene multiplex PCR was found to be highly specific and sensitive, enhancing the detection limit of mixed infections. Cox gene multiplex PCR showed a sensitivity of 100% and a specificity of 97%. This approach can be used as an alternative diagnostic method as it offers higher diagnostic performance and is amenable to high throughput scaling up for a larger sample size at low cost.

DNA recovery from used malaria RDT to detect Plasmodium species and to assess Plasmodium falciparum genetic diversity: a pilot study in Madagascar

Background

Rapid diagnostic tests (RDT) are widely used for malaria diagnosis in Madagascar, where Plasmodium falciparum is the predominant species. Molecular diagnosis is essential for malaria surveillance, but requires additional blood samples for DNA extraction. Used RDTs is an attractive alternative that can be used as a source of DNA. Plasmodium falciparum genetic diversity and multiplicity of infection, usually determined by the genotyping of polymorphic regions of merozoite surface proteins 1 and 2 genes (msp1, msp2), and the repeated region RII of the glutamate-rich protein gene (glurp) have been associated with malaria transmission levels and subsequently with the impact of the deployed control strategies.

Thus, the study aims to use RDT as DNA source to detect Plasmodium species, to characterize Plasmodium falciparum genetic diversity and determine the multiplicity of infection.

Methods

A pilot study was conducted in two sites with different epidemiological patterns: Ankazomborona (low transmission area) and Matanga (high transmission area). On May 2018, used RDT (SD BIOLINE Malaria Ag P.f/Pan, 05FK63) were collected as DNA source. Plasmodium DNA was extracted by simple elution with nuclease free water. Nested-PCR were performed to confirm Plasmodium species and to analyse P. falciparum msp1, msp2 and glurp genes polymorphisms.

Results

Amongst the 170 obtained samples (N = 74 from Ankazomborona and N = 96 from Matanga), Plasmodium positivity rate was 23.5% (40/170) [95% CI 17.5–30.8%] by nested-PCR with 92.2% (37/40) positive to P. falciparum, 5% (2/40) to Plasmodium vivax and 2.5% (1/40) to P. falciparum/P. vivax mixed infection. Results showed high polymorphisms in P. falciparum msp1, msp2 and glurp genes. Multiple infection rate was 28.6% [95% CI 12.2–52.3%]. The mean of MOI was 1.79 ± 0.74.

Conclusion

This pilot study highlighted that malaria diagnosis and molecular analysis are possible by using used malaria RDT. A large-scale study needs to be conducted to assess more comprehensively malaria parasites transmission levels and provide new data for guiding the implementation of local strategies for malaria control and elimination.

Trial registration Retrospectively registered

Genetic polymorphism of Plasmodium falciparum msp-1, msp-2 and glurp vaccine candidate genes in pre-artemisinin era clinical isolates from Lakhimpur district in Assam, Northeast India

Background

Northeast India shares its international border with Southeast Asia and has a number of malaria endemic zones. Monitoring genetic diversity of malaria parasites is important in this area as drug resistance and increasing genetic diversity form a vicious cycle in which one favours the development of the other. This retrospective study was done to evaluate the genetic diversity patterns in Plasmodium falciparum strains circulating in North Lakhimpur area of Assam in the pre-artemisinin era and compare the findings with current diversity patterns.

Methods

Genomic DNA extraction was done from archived blood spot samples collected in 2006 from malaria-positive cases in Lakhimpur district of Assam, Northeast India. Three antigenic markers of genetic diversity were studied – msp-1 (block-2), msp-2 (block-3) and the glurp RII region of P. falciparum using nested PCR.

Results

Allelic diversity was examined in 71 isolates and high polymorphism was observed. In msp-1, eight genotypes were detected; K1 (single allele), MAD20 (six different alleles) and RO33 (single allele) allelic families were noted. Among msp-2 genotypes, 22 distinct alleles were observed out of which FC27 had six alleles and IC/3D7 had 16 alleles. In RII region of glurp, nine genotypes were obtained. Expected heterozygosity (H_E) values of the three antigenic markers were 0.72, 0.81 and 0.88, respectively. Multiplicity of infection (MOI) values noted were 1.28, 1.84 and 1.04 for msp-1, msp-2 and glurp, respectively.

Conclusion

Results suggest a high level of genetic diversity in P. falciparum msp (block-2 of msp-1 and block-3 of msp-2) and the glurp RII region in Northeast India in the pre-artemisinin era when chloroqunine was the primary drug used for uncomplicated falciparum malaria. Comparison with current studies have revealed that the genetic diversity in these genes is still high in this region, complicating malaria vaccine research.

Plasmodium falciparum Clinical Isolates Reveal Analogous Circulation of 3D7 and FC27 Allelic Variants and Multiplicity of Infection in Urban and Rural Settings: The Case of Adama and Its Surroundings, Oromia, Ethiopia

Background

Despite significant progress achieved globally in reducing malaria burden, still it is one of the major public health and economic problems in Ethiopia. Investigation of the local genetic polymorphism of P. falciparum, the most virulent and predominant malaria parasite primarily targeted in malaria control and elimination program, is paramount to assess intensity of parasite transmission. Analysis of the block 3 region of the msp-2 gene of P. falciparum provides strong molecular evidence to evaluate the real picture of malaria epidemiology to fine-tune the ongoing control and elimination programs in the region. Thus, this study was aimed at examining the status of such polymorphic gene and its implications in Adama and its surroundings.

Methods

148 isolates from patients with uncomplicated falciparum malaria were collected in the study from September 2019 to August 2020. Tween® 20 and the Chelex method were employed for parasite DNA extraction. msp-2 allelic families were genotyped by using nested polymerase chain reaction targeting its 3D7 and FC27 allelic variants followed by gel electrophoresis for fragment analysis.

Results

Seventeen different polymorphic forms of msp-2 allelic fragments were detected in the study area. Moreover, 47 (31.8%) and 41(27.7%) were detected for 3D7 and FC27 allelic families, respectively. Furthermore, the multiclonal allele type accounted for 60 (40.5%). The mean MOI was 1.4, and the heterogeneity index (He) is 0.49 indicating nearly intermediate malaria transmission in the study area.

Conclusions

The study revealed nearly intermediate genetic diversity and mean MOI of P. falciparum in the study area, demanding further scale up of the ongoing control and elimination efforts.

Genomic miscellany and allelic frequencies of Plasmodium falciparum msp-1, msp-2 and glurp in parasite isolates

Introduction

The genomic miscellany of malaria parasites can help inform the intensity of malaria transmission and identify potential deficiencies in malaria control programs. This study was aimed at investigating the genomic miscellany, allele frequencies, and MOI of P. falciparum infection.

Methods

A total of 85 P. falciparum confirmed isolates out of 100 were included in this study that were collected from P. falciparum patients aged 4 months to 60 years in nine districts of Khyber Pakhtunkhwa Province. Parasite DNA was extracted from 200µL whole blood samples using the Qiagen DNA extraction kit following the manufacturer’s instructions. The polymorphic regions of msp-1, msp-2 and glurp loci were genotyped using nested PCR followed by gel electrophoresis for amplified fragments identification and subsequent data analysis.

Results

Out of 85 P. falciparum infections detected, 30 were msp-1 and 32 were msp-2 alleles specific. Successful amplification occurred in 88.23% (75/85) isolates for msp-1, 78.9% (67/85) for msp-2 and 70% (60/85) for glurp gene. In msp-1, the K1 allelic family was predominantly prevalent as 66.66% (50/75), followed by RO33 and MAD20. The frequency of samples with single infection having only K1, MAD20 and RO33 were 21.34% (16/75), 8% (6/75), and 10.67% (8/75), respectively. In msp-2, both the FC27 and 3D7 allelic families revealed almost the same frequencies as 70.14% (47/67) and 67.16% (45/67), respectively. Nine glurp RII region alleles were identified in 60 isolates. The overall mean multiplicity of infection for msp genes was 1.6 with 1.8 for msp-1 and 1.4 for msp-2, while for glurp the MOI was 1.03. There was no significant association between multiplicity of infection and age groups (Spearman’s rank coefficient = 0.050; P = 0.6) while MOI and parasite density correlated for only msp-2 allelic marker.

Conclusions

The study showed high genetic diversity and allelic frequency with multiple clones of msp-1, msp-2 and glurp in P. falciparum isolates in Khyber Pakhtunkhwa, Pakistan. In the present study the genotype data may provide valuable information essential for monitoring the impact of malaria eradication efforts in this region.

Detection of high frequency of MAD20 allelic variants of Plasmodium falciparum merozoite surface protein 1 gene from Adama and its surroundings, Oromia, Ethiopia

Background

One of the major challenges in developing an effective vaccine against asexual stages of Plasmodium falciparum is genetic polymorphism within parasite population. Understanding the genetic polymorphism like block 2 region of merozoite surface protein-1 (msp-1) gene of P. falciparum enlighten mechanisms underlining disease pathology, identification of the parasite clone profile from the isolates, transmission intensity and potential deficiencies of the ongoing malaria control and elimination efforts in the locality. Detailed understanding of local genetic polymorphism is an input to pave the way for better management, control and elimination of malaria. The aim of this study was to detect the most frequent allelic variant of the msp-1 gene of P. falciparum clinical isolates from selected health facilities in Adama town and its surroundings, Oromia, Ethiopia.

Methods

One hundred thirty-nine clinical isolates were successfully amplified for msp-1 gene using specific primers. Nested PCR amplification was conducted targeting K1, MAD20, and R033 alleles followed by gel electrophoresis for fragment analysis. Based on the detection of a PCR fragment, infections were classified as monoclonal or multiple infections.

Results

19 different size polymorphism of msp-1 gene were identified in the study, with 67(48%) MAD20, 18 (13%) K-1 and 18 (13%) RO33 allelic family. Whereas, the multiple infections were 21(15%), 8 (5.8%), 4(2.9%), 3(2.2%) for MAD20 + K-1, MAD20 + RO33, K-1 + RO33, and MAD20 + K-1, RO33, respectively. The overall Multiplicity of infection (MOI) was 1.3 and the expected heterozygosity (He) was 0.39 indicating slightly low falciparum malaria transmission.

Conclusion

The status of msp-1 allele size polymorphism, MOI and He observed in the study revealed the presence of slightly low genetic diversity of P. falciparum clinical isolates. However, highly frequent MAD20 allelic variant was detected from clinical isolates in the study area. Moreover, the driving force that led to high predominance of MAD20 allelic variant revealed in such malaria declining region demands further research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03914-9.

A Genotyping Study in Benin Comparing the Carriage of Plasmodium falciparum Infections Before Pregnancy and in Early Pregnancy: Story of a Persistent Infection

Background

Malaria infections in the first trimester of pregnancy are frequent and deleterious for both mother and child health. To investigate if these early infections are newly acquired or already present in the host, we assessed whether parasites detected before pregnancy and those detected in early pregnancy are the same infection.

Methods

We used data from the preconceptional “RECIPAL” study (Benin, 2014–2017). Sixty-three pregnant women of 411 included who had a malaria infection detected by quantitative polymerase chain reaction both before pregnancy and at the first antenatal care (ANC) visit were selected for this study. Two highly polymorphic markers, msp-2 and glurp, and a fragment-analysis method were used to enumerate the Plasmodium falciparum genotypes and to quantify their proportions within isolates. An infection was considered as persistent when identical msp-2 and glurp genotypes were found in the corresponding prepregnancy and early-pregnancy samples.

Results

The median time between the 2 malaria screenings was 3 months. The median gestational age at the first ANC visit was 6.4 weeks. Most infections before pregnancy were submicroscopic infections. Based on both msp-2 and glurp genotyping, the infection was similar before and in early pregnancy in 46% (29/63) of cases.

Conclusions

Almost half of P. falciparum infections detected in the first trimester originate before pregnancy. Protecting young women from malaria infection before pregnancy might reduce the prevalence of malaria in early pregnancy and its related poor maternal and birth outcomes.

Genetic diversity of Plasmodium falciparum populations in three malaria transmission settings in Madagascar

BACKGROUND

Assessment of the genetic diversity of Plasmodium falciparum parasites from various malaria transmission settings could help to define tailored local strategies for malaria control and elimination. Such assessments are currently scarce in Madagascar. The study presented here aimed to bridge this gap by investigating the genetic diversity of P. falciparum populations in three epidemiological strata (Equatorial, Tropical and Fringes) in Madagascar.

METHODS

Two-hundred and sixty-six P. falciparum isolates were obtained from patients with uncomplicated malaria enrolled in clinical drug efficacy studies conducted at health centres in Tsaratanana (Equatorial stratum), Antanimbary (Tropical stratum) and Anjoma Ramartina (Fringes) in 2013 and 2016. Parasite DNA was extracted from blood samples collected before anti-malarial treatment. Plasmodium species were identified by nested PCR targeting the 18 S rRNA gene. The genetic profiles of P. falciparum parasites were defined by allele-specific nested PCR on the polymorphic regions of the msp-1 and msp-2 genes.

RESULTS

Fifty-eight alleles were detected in the P. falciparum samples tested: 18 alleles for msp-1 and 40 for msp-2. K1 (62.9%, 139/221) and FC27 (69.5%, 114/164) were the principal msp-1 and msp-2 allele families detected, although the proportions of the msp-1 and msp-2 alleles varied significantly between sites. Polyclonal infections were more frequent at sites in the Equatorial stratum (69.8%) than at sites in the Tropical stratum (60.5%) or Fringes (58.1%). Population genetics analyses showed that genetic diversity was similar between sites and that parasite flow within sites was limited.

CONCLUSIONS

This study provides recent information about the genetic diversity of P. falciparum populations in three transmission strata in Madagascar, and valuable baseline data for further evaluation of the impact of the control measures implemented in Madagascar.

Genetic polymorphisms of Plasmodium falciparum isolates from Melka-Werer, North East Ethiopia based on the merozoite surface protein-2 (msp-2) gene as a molecular marker

Background

The characterization of parasite populations circulating in malaria endemic areas is necessary to evaluate the success of ongoing interventions and malaria control strategies. This study was designed to investigate the genetic diversity of Plasmodium falciparum isolates from the semi-arid area in North East Ethiopia, using the highly polymorphic merozoite surface protein-2 (msp2) gene as a molecular marker.

Methods

Dried blood spot isolates were collected from patients with P. falciparum infection between September 2014 and January 2015 from Melka-Werer, North East Ethiopia. Parasite DNA was extracted and genotyped using allele-specific nested polymerase chain reactions for msp2.

Results

52 isolates were collected with msp2 identified in 41 (78.8%) isolates. Allele typing of the msp2 gene detected the 3D7/IC allelic family in 54% and FC27 allelic family in 46%. A total of 14 different msp2 genotypes were detected including 6 belonging to the 3D7/IC family and 8 to the FC27 family. Forty percent of isolates had multiple genotypes and the overall mean multiplicity of infections (MOI) was 1.2 (95%CI 0.96–1.42). The heterozygosity index was 0.50 for the msp2 locus. There was no difference in MOI between age groups. A negative correlation between parasite density and multiplicity of infection was found (p = 0.02).

Conclusion

Plasmodium falciparum isolates from the semi-arid area of North East Ethiopia are mainly monoclonal with low MOI and limited genetic diversity in the study population.

Prevalence of Asymptomatic Malaria Parasitemia in Odisha, India: A Challenge to Malaria Elimination

The prevalence of malaria in India is decreasing, but it remains a major concern for public health administration. The role of submicroscopic malaria and asymptomatic malaria parasitemia and their persistence is being explored. A cross-sectional survey was conducted in the Kandhamal district of Odisha (India) during May-June 2017. Blood samples were collected from 1897 individuals for screening of asymptomatic parasitemia. Samples were screened using rapid diagnostic tests (RDTs) and examined microscopically for Plasmodium species. Approximately 30% of randomly selected samples (n = 586) were analyzed using real-time PCR (qPCR), and the genetic diversity of Plasmodium falciparum was analyzed. The prevalence of Plasmodium species among asymptomatic individuals detected using qPCR was 18%, which was significantly higher than that detected by microscopy examination (5.5%) or RDT (7.3%). Of these, 37% had submicroscopic malaria. The species-specific prevalence among asymptomatic malaria-positive cases for P. falciparum, Plasmodium vivax, and mixed infection (P. falciparum and P. vivax) by qPCR was 57%, 29%, and 14%, respectively. The multiplicity of infection was 1.6 and 1.2 for the merozoite surface protein-1 gene (msp1) and (msp2), respectively. Expected heterozygosity was 0.64 and 0.47 for msp1 and msp2, respectively. A significant proportion of the study population, 105/586 (18%), was found to be a reservoir for malaria infection, and identification of this group will help in the development of elimination strategies.

Genetic diversity and complexity of Plasmodium falciparum infections in the microenvironment among siblings of the same household in North-Central Nigeria

Background

Plasmodium falciparum parasites are known to exhibit extensive genetic diversity in areas of high transmission intensity and infected individuals in such communities often harbour several complex mixtures of parasite clones with different genetic characteristics. However, in the micro-environment, the extent of genetic diversity of P. falciparum parasites remain largely unknown. In this study therefore, the complexity of P. falciparum infections in households was investigated among symptomatic siblings, living under the same roof in north-central Nigeria.

Methods

Children were enrolled into the study if they were at least two from a household and presented with symptoms of uncomplicated malaria. Clinical malaria was confirmed by light microscopy of Giemsa-stained thick and thin blood films. Genomic DNA was isolated from blood spots on filter paper. Molecular characterization of P. falciparum isolates was done by allele-specific nested PCR of the highly polymorphic merozoite surface protein-2 (msp-2) gene.

Results

Ninety-three children from 43 households were enrolled into this study. A total of 26 different msp-2 alleles were identified from 215 fragments (range: 180–480 bp). Majority of the isolates [65.6% (n = 61)] were polyclonal infections consisting of 2–6 clones and were significantly more common with the FC27 allelic family (p = 0.036). The multiplicity of infection (MOI) per household ranged from 1.0 to 4.5 while the overall MOI in the study population was 2.31. The pattern of distribution of msp-2 allele types among the households fell into two categories: households where both msp-2 allele types (FC27 and 3D7) were present; households where only one msp-2 allele type (FC27 or 3D7) was present. Majority of the households [88.4% (n = 38)], had both msp-2 allele types but they were disproportionately distributed among the children while in a few households [11.6% (n = 5)], all the children were infected with only one type of msp-2 allele.

Conclusion

These findings showed that P. falciparum isolates exhibit remarkable degree of genetic diversity in the micro-environment and are composed mainly of multiclonal infections, which is an indication of a high ongoing parasite transmission. This suggests that the micro-environment is an important area of focus for malaria control interventions and for evaluating intervention programmes.

Genetic diversity of Plasmodium falciparum in Grande Comore Island

Background

Despite several control interventions resulting in a considerable decrease in malaria prevalence in the Union of the Comoros, the disease remains a public health problem with high transmission in Grande Comore compared to neighbouring islands. In this country, only a few studies investigating the genetic diversity of Plasmodium falciparum have been performed so far. For this reason, this study aims to examine the genetic diversity of P. falciparum by studying samples collected in Grande Comore in 2012 and 2013, using merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2) and single nucleotide polymorphism (SNP) genetic markers.

Methods

A total of 162 positive rapid diagnostic test (RDT) samples from Grande Comore were used to extract parasite DNA. Allelic families K1, Mad20 and RO33 of the msp1 gene as well as allelic families IC3D7 and FC37 of the msp2 gene were determined by using nested PCR. Additionally, 50 out of 151 samples were genotyped to study 24 SNPs by using high resolution melting (HRM).

Results

Two allelic families were predominant, the K1 family of msp1 gene (55%) and the FC27 family of msp2 gene (47.4%). Among 50 samples genotyped for 24 SNPs, 42 (84%) yielded interpretable results. Out of these isolates, 36 (85%) were genetically unique and 6 (15%) grouped into two clusters. The genetic diversity of P. falciparum calculated from msp1 and msp2 genes and SNPs was 0.82 and 0.61, respectively.

Conclusion

In summary, a large genetic diversity of P. falciparum was observed in Grande Comore. This may favour persistence of malaria and might be one of the reasons for the high malaria transmission compared to neighbouring islands. Further surveillance of P. falciparum isolates, mainly through environmental management and vector control, is warranted until complete elimination is attained.

Genetic diversity and genotype multiplicity of Plasmodium falciparum infection in patients with uncomplicated malaria in Chewaka district, Ethiopia

Background

Genetic diversity in Plasmodium falciparum poses a major threat to malaria control and elimination interventions. Characterization of the genetic diversity of P. falciparum strains can be used to assess intensity of parasite transmission and identify potential deficiencies in malaria control programmes, which provides vital information to evaluating malaria elimination efforts. This study investigated the P. falciparum genetic diversity and genotype multiplicity of infection in parasite isolates from cases with uncomplicated P. falciparum malaria in Southwest Ethiopia.

Methods

A total of 80 P. falciparum microscopy and qPCR positive blood samples were collected from study participants aged 6 months to 60 years, who visited the health facilities during study evaluating the efficacy of artemether-lumefantrine from September–December, 2017. Polymorphic regions of the msp-1 and msp-2 were genotyped by nested polymerase chain reactions (nPCR) followed by gel electrophoresis for fragment analysis.

Results

Of 80 qPCR-positive samples analysed for polymorphisms on msp-1 and msp-2 genes, the efficiency of msp-1 and msp-2 gene amplification reactions with family-specific primers were 95% and 98.8%, respectively. Allelic variation of 90% (72/80) for msp-1 and 86.2% (69/80) for msp-2 were observed. K1 was the predominant msp-1 allelic family detected in 20.8% (15/72) of the samples followed by MAD20 and RO33. Within msp-2, allelic family FC27 showed a higher frequency (26.1%) compared to IC/3D7 (15.9%). Ten different alleles were observed in msp-1 with 6 alleles for K1, 3 alleles for MAD20 and 1 allele for RO33. In msp-2, 19 individual alleles were detected with 10 alleles for FC27 and 9 alleles for 3D7. Eighty percent (80%) of isolates had multiple genotypes and the overall mean multiplicity of infection was 3.2 (95% CI 2.87–3.46). The heterozygosity indices were 0.43 and 0.85 for msp-1 and msp-2, respectively. There was no significant association between multiplicity of infection and age or parasite density.

Conclusions

The study revealed high levels of genetic diversity and mixed-strain infections of P. falciparum populations in Chewaka district, Ethiopia, suggesting that both endemicity level and malaria transmission remain high and that strengthened control efforts are needed in Ethiopia.

Genetic diversity of Plasmodium falciparum and genetic profile in children affected by uncomplicated malaria in Cameroon

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. Trial registration This study was approved by Cameroon National Ethics Committee. It is a randomized controlled trial retrospectively registered in NIH U.S. National Library of Medicine, ClinicalTrials.gov on the 28/11/2016 at https://clinicaltrials.gov/ct2/show/NCT02974348 with the registration number NCT02974348.

Genetic diversity of Plasmodium falciparum isolates from patients with uncomplicated and severe malaria based on msp-1 and msp-2 genes in Gublak, North West Ethiopia

BACKGROUND

Malaria infection can present with a wide variety of symptoms, ranging from mild to severe. Plasmodium falciparum isolates in uncomplicated and severe malaria infections may have different parasite genetic profiles. This study was conducted to assess differences in genetic diversity and allelic frequencies in P. falciparum isolates according to malaria severity and age of patients in the Gublack area, northwest Ethiopia.

METHODS

Cross-sectional health facility-based study conducted in Gublak, Ethiopia between July, 2017 and October, 2017. Symptomatic P. falciparum malaria patients with microscopically-confirmed infection were enrolled. Parasite DNA was extracted from filter paper blood spots and the polymorphic regions of the msp-1 and msp-2 genes were genotyped using allele-specific nested-PCR with fragment analysis by gel electrophoresis.

RESULTS

A total of 118 patients were enrolled including 95 (80.5%) with uncomplicated infection and 23 (19.5%) with severe disease. In msp-1, the K1 allelic family was similarly prevalent in uncomplicated 42 (44.2%) and severe disease 12 (52.2%). In msp-2, FC27 was detected in 55 (57.9%) of uncomplicated infections and IC/3D7 in 14 (60.9%) of severe infections. 76 (64.4%) of the 118 isolates contained multiple genotypes; 56 (58.9%) in uncomplicated infections and 19 (82.6%) in severe infections. The overall of multiplicity of infection was 2.2 (95% CI 1.98-2.42) with 1.4 (95% CI 1.23-1.55) and 1.7 (95% CI 1.49-1.86) for msp-1 and msp-2, respectively. Multiplicity of infection was significantly higher in severe than uncomplicated infections (3.0 (95% CI 2.61-3.47) versus 2.0 (95% CI 1.83-2.23), respectively, p = 0.001). There was no difference in multiplicity of infection across age groups (p = 0.104).

CONCLUSION

Patients with severe malaria were more likely to have multiclonal infections. Further studies are needed to describe the association between P. falciparum genotypes and malaria severity in different malaria transmission areas.

Genetic polymorphism of merozoite surface proteins 1 and 2 of Plasmodium falciparum in the China-Myanmar border region

BACKGROUND

Malaria is a major public health problem in the China-Myanmar border region. The genetic structure of malaria parasite may affect its transmission model and control strategies. The present study was to analyse genetic diversity of Plasmodium falciparum by merozoite surface proteins 1 and 2 (MSP1 and MSP2) and to determine the multiplicity of infection in clinical isolates in the China-Myanmar border region.

METHODS

Venous blood samples (172) and filter paper blood spots (70) of P. falciparum isolates were collected from the patients of the China-Myanmar border region from 2006 to 2011. The genomic DNA was extracted, and the msp1 and msp2 genes were genotyped by nested PCR using allele-specific primers for P. falciparum.

RESULTS

A total of 215 P. falciparum clinical isolates were genotyped at the msp1 (201) and msp2 (204), respectively. For the msp1 gene, MAD20 family was dominant (53.49%), followed by the K1 family (44.65%), and the RO33 family (12.56%). For the msp2 gene, the most frequent allele was the FC27 family (80.93%), followed by the 3D7 family (75.81%). The total multiplicity of infection (MOI) of msp1 and msp2 was 1.76 and 2.21, with a prevalence of 64.19% and 72.09%, respectively. A significant positive correlation between the MOI and parasite density was found in the msp1 gene of P. falciparum. Sequence analysis revealed 38 different alleles of msp1 (14 K1, 23 MAD20, and 1 RO33) and 52 different alleles of msp2 (37 3D7 and 15 FC27).

CONCLUSION

The present study showed the genetic polymorphisms with diverse allele types of msp1 and msp2 as well as the high MOI of P. falciparum clinical isolates in the China-Myanmar border region.

Dynamics of Plasmodium falciparum genetic diversity among asymptomatic and symptomatic children in three epidemiological areas in Cote d'Ivoire

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 cross-sectional 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.