Browsing by Author "Moshi, Ramadhan"

Now showing 1 - 4 of 4

Genetic Diversity of Plasmodium falciparum helical interspersed subtelomeric (phistb) gene in Tanzania and neighboring countries
(Taylor & Francis, 2025-10-28) Mbwambo , Ruth; Pereus, Dativa; Bakari, Catherine; Moshi, Ramadhan; Kisambale, Angelina; Madebe, Rashid; Misago, Seth; Mandara, Celine; Lyimo, Beatus; Mbwambo, Daniel; Aaron, Sijenunu; Lusasi, Abdallah; Lazaro, Samuel; Juma, Gerald; Kulohoma, Benard; Ishengoma, Deus
Background Lysine-rich membrane associated Plasmodium helical interspersed subtelomeric gene (phistb) is a member of the phist family of genes which encodes exported proteins essential for the parasite’s survival within infected red blood cells. Recent studies suggest the phistb gene as a promising malaria vaccine candidate, however its genetic diversity remains understudied. This study assessed the genetic diversity of the phistb gene in regions of varying malaria transmission aiming to generate data and improve our understanding of this promising malaria vaccine candidate gene. Methods Genomic data from 1,472 P. falciparum samples from Tanzania, Kenya, Uganda, and Ethiopia were retrieved in VCF format from the MalariaGEN Pf7 database. Variants were filtered to include only biallelic SNPs with VQSLOD > 1 and “PASS” status. Genetic diversity, differentiation, and selection signatures were analyzed using population genetics metrics. Results After filtering, 1,312 samples were retained. Wright’s inbreeding coefficient (Fws) showed 875 (66.7%) monoclonal infections, highest in Ethiopia (95.3%), followed by Tanzania (67.2%), Kenya (65.7%), and Uganda (50%). Among these 875 monoclonal samples, 88 haplotypes were identified, with Hap_1 and Hap_13 comprising 59% of samples. Nucleotide and haplotype diversity in Kenya was 0.097, and 0.88 respectively, which were relatively higher than in the other study populations. The overall fixation index (Fst) was <0.05, and Principal Component Analysis revealed no clear population sub-structure among countries. Negative Tajima’s D values in Tanzania, Kenya, and Ethiopia indicated an excess of low-frequency alleles. Conclusion This study reports low genetic diversity of the phistb gene in the four countries despite varying malaria transmission intensity among them, thus making it a suitable candidate gene for malaria vaccine. Further studies should be conducted to assess individual antibodies recognition of the phistb variants and the ability to elicit cross reactivity to further support its potential as a vaccine candidate.
Genetic diversity of Plasmodium falciparum reticulocyte binding protein homologue-5, which is a potential malaria vaccine candidate: baseline data from areas of varying malaria endemicity in Mainland Tanzania
(BioMed Central, 2025-01-27) Kisambale, Angelina; Pereus, Dativa; Mandai, Salehe; Lyimo, Beatus; Bakari, Catherine; Chacha, Gervas; Mbwambo, Ruth; Moshi, Ramadhan; Petro, Daniel; Challe, Daniel; Seth, Misago; Madebe, Rashid; Budodo, Rule; Aaron, Sijenunu; Mbwambo, Daniel; Lusasi, Abdallah; Kajange, Stella; Lazaro, Samwel; Kapologwe, Ntuli; Mandara, Celine; Ishengoma, Deus
Background The limited efficacy of the two recently approved malaria vaccines, RTS,S/AS01 and R21/Matrix- M™, highlights the need for alternative vaccine candidate genes. Plasmodium falciparum Reticulocyte Binding Protein Homologue 5 (Pfrh5) is a promising malaria vaccine candidate, given its limited polymorphism, its essential role in parasite survival, a lack of immune selection pressure and higher efficacy against multiple parasites strains. This study evaluated the genetic diversity of Pfrh5 gene among parasites from regions with varying malaria transmission intensities in Mainland Tanzania, to generate baseline data for this potential malaria vaccine candidate. Methods This study utilized secondary data of 697 whole-genome sequences which were generated by the MalariaGEN Community Network. The samples which were sequenced to generated the data were collected between 2010 and 2015 from five districts within five regions of Mainland Tanzania, with varying endemicities (Morogoro-urban district in Morogoro region, Muheza in Tanga, Kigoma-Ujiji in Kigoma, Muleba in Kagera, and Nachingwea district in Lindi region). Wright's fixation index (FST), Wright’s inbreeding coefficient (Fws), Principal component analysis (PCA), nucleotide diversity (π), haplotype network, haplotype diversity (Hd), Tajima's D, and Linkage disequilibrium (LD) were used to assess the diversity of the gene. Results Of the sequences used in this study, 84.5% (n = 589/697) passed quality control and 313 (53.1%) were monoclonal (contained infections from a single strain of P. falciparum) and were used for haplotype diversity and haplotype network analysis. High within-host diversity (Fws < 0.95) was reported in Kigoma-Ujiji (60.7%), Morogoro-urban (53.1%), and Nachingwea (50.8%), while Muleba (53.9%) and Muheza (61.6%) had low within-host diversity (Fws ≥ 0.95). PCA did not show any population structure and the mean FST value was 0.015. Low nucleotide diversity values were observed across the study sites (mean π = 0.00056). A total of 27 haplotypes were observed among the 313 monoclonal samples and under-fives exhibited higher haplotype counts. The Pf3D7 was detected as Hap_1, which occurred in 16/313 (5.1%) monoclonal sequences. Negative Tajima's D values were observed among the parasite populations in all the study sites. Conclusion Low levels of polymorphism in the pfrh5 gene were observed based on low nucleotide and haplotype diversity, a lack of population structure and negative Tajima’s D values. This study provides essential data on the diversity of the Pfrh5 gene indicating that it can be considered in the development of the next generation malaria vaccines. Robust and intensive studies of this and other candidate genes are crucial to support the prioritization of the Pfrh5 gene for potential inclusion in a broadly cross-protective malaria vaccine
Temporal and spatial trends of the prevalence of infections caused by Plasmodium parasites among rural community members in three regions with varying transmission intensities in Mainland Tanzania
(Springer Nature, 2025-09-30) Challe, Daniel; Petro, Daniel; Francis, Filbert; Seth, Misago; Madebe , Rashid; Mandai, Salehe; Budodo, Rule; Kisambale,Angelina; Chacha, Gervas; Moshi, Ramadhan; Mbwambo , Ruth; Pereus, Dativa; Bakari, Catherine; Mbata, Doris; Lyimo, Beatus
Background Recent reports showed persistence of malaria transmission and disease burden in rural communities, which has limited the impact of ongoing control and elimination strategies. This study investigated temporal and spatial trends of the prevalence of infections caused by Plasmodium parasites among community members from three regions with heterogeneous transmission intensities, following intensive use of different malaria control interventions in the past 20 years in Mainland Tanzania. Methods Community surveys were conducted from 2021 to 2023, and involved 8166 individuals aged ≥ 6, living in rural communities in three regions of Kigoma, Ruvuma and Tanga. Structured questionnaires were used to collect demographic, anthropometric, clinical, parasitological, bed net use, type of house (traditional or modern), and socio-economic status (SES) data. The trends of the prevalence of infections caused by Plasmodium parasites detected using rapid diagnostic tests (RDTs) were determined using descriptive statistics and, and factors associated with the infections were determined using modified Poisson regression. The results were presented as crude (cPR) and adjusted prevalence ratios (aPR), with their corresponding 95% confidence intervals (CI). Results The overall prevalence was 23.2% (n = 1896), with significant variations across regions and years (22.9% in 2021, 20.6% in 2022, and 26.9% in 2023; p < 0.001). School children (5– < 15 years; p < 0.001) and males (p < 0.001) had significantly higher prevalence in all years. The prevalence increased consistently in individuals with a history of fever within 48 h before the survey, from 40.1% in 2021 to 45.7% in 2022 (p = 0.049), and further to 58.6% in 2023 (p < 0.001). The prevalence and odds of infections were significantly higher among individuals who were not using bed nets (p ≤ 0.003) and those living in households with traditional houses (p < 0.001) or low SES (p < 0.001). Conclusion The prevalence of infections caused by Plasmodium parasites varied significantly over the 3 years, in the three regions, and among individuals with different demographic and clinical features. The highest prevalence was in 2023, and among school children, males, individuals with a fever history, and participants living in households with traditional houses or low SES. These findings underscore the need for targeted and adaptive malaria control strategies to address emerging hotspots and vulnerable groups or populations.
Trends of malaria prevalence among individuals from rural communities in three regions with varying transmission intensities in Mainland Tanzania; Data from 2021 - 2023 community cross-sectional surveys
(medRxiv, 2025-02-14) Challe, Daniel; Petro, Daniel; Francis, Filbert; Seth, Misago; Madebe, Rashid; Mandai, Salehe; Budodo, Rule; Kisambale, Angelina; Chacha, Gervas; Moshi, Ramadhan; Mbwambo, Ruth; Pereus, Dativa; Bakari, Catherine; Mbata, Doris; Lyimo, Beatus; Kanyankole, Grace; Aaron, Sijenunu; Mbwambo, Daniel; Kajange, Stella; Lazaro, Samwel; Kapologwe, Ntuli; Mandara, Celine; Makene, Vedastus; Deus S. Ishengoma
Background Recent reports showed the persistence of malaria transmission and disease burden in rural communities, which have limited the impact of ongoing control and elimination strategies. This study investigated the trends of malaria prevalence among community members from three regions of Mainland Tanzania with varying transmission intensities. Methods Community surveys were conducted from 2021 to 2023 and involved individuals aged ≥6 months in three regions Kigoma and Ruvuma (with high malaria transmission intensities) and Tanga (moderate transmission). Interviews were conducted using structured questionnaires, to collect anthropometric, clinical, parasitological (testing for malaria using rapid diagnostic tests (RDTs), type of house and socio-economic status (SES) data. Modified Poisson regression was used to identify factors associated with malaria infections and the results were presented as crude (cPR) and adjusted prevalence ratios (aPR). Results Malaria infections by RDTs were detected in 1,896 (23.2%, n=8,166) individuals, with significant variations across regions and years (22.9% in 2021, 20.6% in 2022, and 26.9% in 2023; p<0.001). The highest prevalence of malaria infections was in Kigoma in 2023 (35.6%) while the lowest was in Tanga in 2022 (10.5%). School children (5 – <15 years) had significantly higher prevalence (38.2% in 2021, 26.2% in 2022, and 34.4% in 2023 (p<0.001) as did males (26.7% in 2021, 25.4% in 2022 and 31.2% in 2023, p<0.001). Higher likelihood of malaria infections was in school children (aPR: 1.94, 95% CI: 1.67 – 2.25, p<0.001), males (aPR=1.24 95%CI: 1.14–1.34, p<0.001), individuals living in traditional houses (aPR=1.14, 95% CI: 1.01 – 1.28, p = 0.037), among individuals with moderate (aPR=1.27, 95% CI: 1.13 – 1.43, p<0.001) or low SES (aPR = 1.39, 95% CI: 1.24 – 1.55, p<0.001), and those with fever at presentation (axillary temperature ≥37.5°C; aPR = 1.34, 95% CI: 1.09 – 1.64, p = 0.005) or fever history within 48 hours before the survey (aPR = 3.55, 95% CI: 3.26–3.87, p<0.001). The likelihood of infections was also higher in Ruvuma (aPR=1.98, 95%CI: 1.77–2.21, p<0.001) and Kigoma (aPR=1.28, 95%CI: 1.15–1.42, p<0.001) regions compared to Tanga. The likelihood of malaria infections was similar among participants based on bed net ownership (aPR: 1.27, 95%CI: 0.80 – 2.01, p = 0.306) or use (aPR: 1.01, 95%CI: 0.64 – 1.50, p=0.920). Conclusion The study showed spatial and temporal variations of malaria prevalence, with the highest prevalence in 2023 and the lowest in 2022. Groups at higher risk of malaria infections included school children, males, participants with fever, low or moderate SES, and those who lived in traditional houses. Targeted interventions are urgently needed for areas with persistently high transmission and vulnerable groups, particularly in rural communities.