Browsing by Author "Ocan, Moses"

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    Combination of different intervention strategies for malaria mosquito vector control in Uganda: A review of secondary data of two districts with moderate to high disease transmission
    (Public Library of Science (PLOS), 2026-07-06) Okek, Erick Jacob; Nambatya, Winnie; Nakalembe, Loyce; Awor, Silvia; Musinguzi, Benson; Drasiku, Amos; Obondo, Sande James; Lukindu, Martin; Lutwama, Julius; Kayondo, Jonathan; Ocan, Moses
    Background Indoor residual spraying (IRS) and insecticide treated bed nets (ITNs) used either singly or in combination are the main mass mosquito vector control measures for malaria control. Despite their widespread use, malaria transmission rates remain high, the burden is unacceptably huge, and yet the disease is completely preventable. This study measured the impact of compounds used in different types and campaigns of IRS and ITNs, different permutations of IRS + ITNs on malaria test positivity rates in high disease transmission settings of Yumbe district and Gulu district. Method The Ministry of Health’s District Health Information System 2 (DHIS 2) records on distribution of ITNs, IRS schedules and malaria cases by gender, age and geographical location (Gulu and Yumbe districts) collected over a five-year period (DHIS 2 records accessed on 11th February 2025) were used in the final analysis. Data collection was done using a checklist developed in an Excel spreadsheet. Data on the following were extracted; socio-demographic characteristics, number of monthly malaria tests, monthly numbers of positive malaria tests, the type of Insecticide Treated Nets (ITNs) distributed, the type of Indoor Residual Spray (IRS) applied and the time points that the interventions were deployed. The data was exported into STATA ver 17.0,cleaned and additional variables generated prior to the interrupted time series and Difference in Difference analysis. The monthly malaria test positivity rate (TPR) was calculated while adjusting for variability in rainfall, temperature and relative humidity. A regression analysis and graphical plots using the Generalized Estimation Equation (GEE) population average models were performed. Results After controlling for monthly variation in rainfall, temperature, and relative humidity, the deployment of malaria vector control interventions in Yumbe district led to a much faster reduction in TPR of 0.006 units/0.56% per month; p < 0.00 (about 5 times faster than Gulu district). The 2020 distribution of Yorkool ITNs in Yumbe did not significantly change the long-term trend in TPR of the district relative to Gulu that maintained distribution of PermaNets ITN (trend change difference = 0.0111, beta = −0.0054, 95% CI:0.1145, 0.1038, p = 0.923). Fludora Fusion demonstrated a profound impact. The difference-in-differences interaction term was highly statistically significant, showing an absolute 21.2% drop in the Malaria Test Positivity Rate in Yumbe District relative to Gulu district (beta = −0.2123, 95% CI: −0.2801, −0.1444, p < 0.001). Following a co-deployment of Actellic 300 CS IRS+ Royal Guard ITNs in Yumbe and distribution of PermaNet ITNs in Gulu, the difference-in-differences interaction term was highly statistically significant, demonstrating an absolute 25.1% drop in the Malaria Test Positivity Rate in Yumbe District compared to Gulu district (beta = −0.2508, 95%CI:-0.3279, −0.1737,p < 0.001). Conclusion In areas of high malaria transmission, deployment of either ITNs alone, IRS alone, or in combination can be an effective tool for malaria case reduction. However, a more sustained and significant reduction is achieved through the simultaneous deployment of IRS and ITNs. Crucially, the efficacy of these combined interventions is highly shaped by the specific classes of insecticides and active compounds utilized within the deployed ITN types and IRS campaigns.
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    Plasmodium falciparum genetic diversity and multiplicity of infection among asymptomatic and symptomatic malaria-infected individuals in Uganda
    (Springer Nature, 2024-11-14) Mwesigwa, Alex; Ocan, Moses; Cummings, Bryan; Musinguzi, Benson; Kiyaga, Shahid; Kiwuwa, Steven M.; Okoboi, Stephen; Castelnuovo, Barbara; Bikaitwoha, Everd Maniple; Kalyango, Joan N.; Karamagi, Charles; Nankabirwa, Joaniter I.; Nsobya, Samuel L.; Byakika-Kibwika, Pauline
    Background: Plasmodium falciparum (P. falciparum) remains a significant public health challenge globally, especially in sub-Saharan Africa (SSA), where it accounts for 99% of all malaria infections. The outcomes of P. falciparum infection vary, ranging from asymptomatic to severe, and are associated with factors such as host immunity, parasite genetic diversity, and multiplicity of infection (MOI). Using seven neutral microsatellite markers, the current study investigated P. falciparum genetic diversity and MOI in both asymptomatic and symptomatic malaria individuals in Uganda. Methods: This cross-sectional study analyzed 225 P. falciparum isolates from both asymptomatic and symptomatic malaria patients, ranging in age from 6 months to ≥ 18 years. P. falciparum genetic diversity, MOI, and multi-locus linkage disequilibrium (LD) were assessed through genotyping of seven neutral microsatellite markers: Poly-α, TA1, TA109, PfPK2, 2490, C2M34–313, and C3M69–383. Genetic data analysis was performed using appropriate genetic analysis software. Results: P. falciparum infections exhibited high genetic diversity in both asymptomatic and symptomatic individuals. The mean expected heterozygosity (He) ranged from 0.79 in symptomatic uncomplicated malaria cases to 0.81 in asymptomatic individuals. There was no significant difference (p = 0.33) in MOI between individuals with asymptomatic and symptomatic infections, with the mean MOI ranging from 1.92 in symptomatic complicated cases to 2.10 in asymptomatic individuals. Polyclonal infections were prevalent, varying from 58.5% in symptomatic complicated malaria to 63% in symptomatic uncomplicated malaria cases. A significant linkage disequilibrium (LD) was observed between asymptomatic and symptomatic uncomplicated/complicated infections (p < 0.01). Genetic differentiation was low, with FST values ranging from 0.0034 to 0.0105 among P. falciparum parasite populations in asymptomatic and symptomatic uncomplicated/complicated infections. Conclusion: There is a high level of P. falciparum genetic diversity and MOI among both symptomatic and asymptomatic individuals in Uganda. Asymptomatic carriers harbor a diverse range of parasites, which poses challenges for malaria control and necessitates targeted interventions to develop effective strategies.
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    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
    (Springer Nature, 2024-04-08) Mwesigwa, Alex; Ocan, Moses; Musinguzi, Benson; Nante, Rachel Wangi; Nankabirwa, Joaniter I.; Kiwuwa, Steven M.; Kinengyere, Alison Annet; Castelnuovo, Barbara; Karamagi, Charles; Obuku, Ekwaro A.; Nsobya, Samuel L.; Mbulaiteye, Sam M.; Byakika-Kibwika, Pauline
    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. 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. 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%)
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    Progression from uncomplicated to severe malaria among children in settings receiving different malaria control interventions in sub-Saharan Africa: a systematic review protocol
    (BMJ Group, 2025-08-11) Okek, Erick Jacob; Lutwama, Julius; Kinengyere, Alison Annet; Asio, Juliet; Awor, Silvia; Le Doare, Kirsty; Musinguzi, Benson; Sande, James Obondo; Ocan, Moses; Kayondo, Jonathan
    Background Different malaria control measures are deployed simultaneously in endemic settings globally, with varying impacts on malaria burden. In sub-Saharan Africa, which bears the greatest burden of malaria, evidence on the impact of implementing various control interventions on malaria immunity remains unknown. This systematic review seeks to collate evidence on the extent of progression from uncomplicated to severe malaria among populations in sub-Saharan Africa settings receiving concurrent deployment of various malaria control measures. Methods The review will use a priori criteria contained in the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. An experienced librarian (AAK) will independently search for articles from the following databases: PubMed, Web of Science, Embase, Scopus and Google Scholar. Boolean operators ‘AND’ and ‘OR’ will be used in the article search. Identified articles will be managed using EndNote. Article screening for inclusion and data extraction will be done in duplicate by two reviewers (EJO, and BM). Data extraction tools will be developed and customised in Excel. Data will be analysed using both narrative and quantitative synthesis. The level of heterogeneity between study outcomes will be measured using the I2 statistic. Subgroup analysis will be conducted to explore heterogeneity and establish the impact of different control interventions on progression from uncomplicated to severe malaria. A full systematic review and meta-analysis is expected to be ready for dissemination by the end of December 2025.