Browsing by Author "Okware, Samuel"

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    Cross-border transmission corridors and diffusion velocities of Ebola-virus in in the Great-lakes basin : a 1976-2025 multilayered phylogeographic analysis.
    (Research Square, 2025) Paasi, George; Okware, Samuel; Olupot-Olupot, Peter
    Background Ebola disease (EBOD) outbreaks are recurrent and highly lethal in the Great-Lakes basin, yet regional scale evolutionary reconstructions are lacking. Objectives To locate the long-term reservoir, quantify cross-border transmission corridors and measure diffusion velocities of EBOD outbreaks across central Africa during 1976–2025. Methods We curated 110 complete Ebola virus genomes from GenBank and BV-BRC, aligned them with MAFFT, and inferred a time-scaled phylogeny in BEAST v1.10.5. A dual-layer Bayesian framework coupled (i) a discrete Bayesian stochastic-search variable-selection (BSSVS) model for country-to-country migration with (ii) a continuous Cauchy relaxed random walk (RRW) for kilometre-scale movement. Posterior trees (300 million states; ESS > 200) were visualised in EvoLaps 2.42; Markov-jump counts, Bayes factors (BF) and branch velocities were extracted. Results Our dual-layer reconstruction shows that Ebola circulation is firmly rooted in north-eastern DRC: 80% of the root posterior density clusters within a 150 km radius of the Yambuku-Ituri-Likati forests axis, identifying this block of lowland rainforest as a persistent enzootic cradle. From that focus, diffusion unfolded in three distinct temporal phases initially as short-range local spread (1976–1987), then as a westward, Congo/Kasai river-mediated wave (1994–2007), and, since 2007, as an east-south-east advance toward Lakes Albert and Edward that underpins recent Ugandan outbreaks. Cross-border movement is dominated by the Lake-Albert corridor: Bayes factors of 32.1 for DRC to Uganda and 26.4 for Uganda to DRC, together with a median 13.4 Markov-jump events, account for three-quarters of all international transitions in the posterior; by contrast, only a single westward leap reaches the Gabon/Cameroon littoral (BF = 6.4). Continuous-model vectors yield a mean radial expansion of 7.9 km year⁻¹ (95% HPD: 5.4–10.6 km year⁻¹), yet the distribution’s heavy tail reveals rare founder events that cover more than 150 km in a single transmission chain. Conclusions A single Yambuku-Ituri-Likati forest axis hearth has seeded all documented EBOD outbreaks, with transmission funnelling chiefly through informal Lake-Albert crossings. Sentinel surveillance in this area, corridor-focused border health teams, and pre-emptive vaccine positioning along the Ituri-Lakes corridor could blunt future outbreaks. Keywords: Ebola virus, Zaire ebolavirus, phylodynamics, phylogeography, Bayesian stochastic search variable selection, continuous diffusion, cross-border transmission, Great Lakes region, Democratic Republic of the Congo (DRC), Uganda
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    High-resolution ecological niche maps identify population-density hot-spots for Ebola disease spillover in Uganda.
    (Research Square, 2025) Paasi, George; Okware, Samuel; Olupot-Olupot, Peter
    Background Uganda experiences recurrent Ebola disease (EBOD) outbreaks, but the only available risk maps pool virus species and resolve five-kilometre grids insufficient for district-level preparedness. Therefore, this study aimed to generate one-kilometre, species-resolved MaxEnt risk surfaces for Uganda (2000–2024) and quantify the population living in predicted spill-over hotspots. Methods We compiled 71 laboratory-confirmed spill-over localities for Sudan, Bundibugyo and imported Zaire ebolaviruses and paired them with eleven minimally collinear environmental and anthropogenic predictors. Species-specific MaxEnt models were tuned with ENMeval (feature classes = L, Q, H; β = 0.5- 3.0) and evaluated by four-fold spatial block cross-validation. A 10% training-presence threshold converted continuous suitability to binary maps; the union surface was stratified into four risk tiers. WorldPop 2023 provided population counts. Results Models showed excellent discrimination: the pooled model achieved a spatially validated AUC of 0.927, while species-specific AUCs ranged from 0.961 to 0.999. Human population density dominated permutation importance (median 77%), followed by precipitation seasonality (7%) and bat-roost probability (8%). Tier 1 pixels (highrisk, cloglog ≥ 0.65) occupied only 58 % of Uganda’s land but contained 13.7 million residents (9 % of the national population), clustering along the Kampala-Hoima corridor and the Albertine Rift escarpment. All 15 historical outbreak epicentres fell within 8 km of Tier 1 or Tier 2 pixels. An alternative checkerboard partition raised mean AUC by Δ = +0.006 and preserved identical tier rankings, confirming robustness. Conclusions One-kilometre, species-resolved MaxEnt maps pinpoint compact geographic targets where intensified One-Health surveillance, GeneXpert diagnostics and future vaccine rings could most effectively curb EBOD emergence in Uganda.
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    Prevalence and factors associated with poor hand hygiene practices among adult carers of children under five in Mbale district Uganda.
    (Scientific Reports, 2025) Nawanga, Jascenti; Alunyo, Patrick Jimmy; Wenani, Daniel; Okibure, Ambrose; Olupot-Olupot, Peter; Mukunya, David; Nekaka, Rebecca; Okolimong, Charles; Okware, Samuel; Matovu, K. B. Joseph
    Background: Proper hand hygiene reduces the risk of hygiene-related diseases among children under five years of age; however, poor hand hygiene practices remain common in many communities. This study determined the prevalence and factors associated with poor hand hygiene practices among adult caregivers of children under five years in Mbale District, Eastern Uganda, to inform context-specific interventions. Methods: We conducted a cross-sectional study in March 2023 among 320 adult caregivers of children under five years. Participants were selected using multistage sampling from three sub counties with the largest under-five populations. Structured questionnaires collected information on socio-demographics, household characteristics, knowledge of hand hygiene, and COVID-19 prevention information. Poor hand hygiene was defined as reporting handwashing at five or fewer of ten critical hand hygiene moments. Multivariable logistic regression was used to identify factors independently associated with poor hand hygiene. Results: Of the 320 caregivers enrolled, 275 (85.9%) were female. The majority were aged 25–34 years (38.4%, n=123), and over half (55.6%, n=178) had primary education. Overall, 28% (n=88) of caregivers engaged in poor hand hygiene practices. In the multivariable analysis, receiving hand hygiene information from Village Health Teams (VHTs) was significantly associated with higher odds of poor hand hygiene (AOR 4.2; 95% CI 1.7-10.4). Caregivers who indicated that hand hygiene protects against COVID-19 had lower odds of poor hand hygiene (AOR 0.16; 95% CI 0.03-0.73). Additionally, inconsistent availability of soap, detergent, or sanitizer at handwashing stations was strongly associated with poor hand hygiene (AOR 8.22; 95% CI 2.03-57.16). No significant associations were observed for education level, child’s age, or type of handwashing facility. Conclusion: Nearly three in ten adult caregivers exhibited poor hand hygiene practices. Poor hand hygiene was associated with receiving information from VHTs and inconsistent access to cleansing materials, whereas knowledge of hand hygiene’s protective benefits against COVID-19 was associated with better practices. Strengthening VHT training and ensuring reliable access to handwashing supplies may help improve hygiene behaviours in Mbale District. Keywords: Hand hygiene practices, adult caregivers, children under five, Mbale District, Uganda.
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    Retreatment TB is a risk factor for multidrug-resistant TB among people with HIV in rural eastern Uganda: A nested case-control study.
    (Elsevier Ltd., 2025) Opolot, Godfrey; Olupot-Olupot, Peter; Okware, Samuel; Izudi, Jonathan
    Rationale: People with human immunodeficiency virus (PWH) have an increased risk of multidrug-resistant TB (MDR-TB) compared to those without HIV. Objective: To investigate the risk factors for MDR-TB among PWH in rural eastern Uganda. Methods: We conducted a nested case–control study at Soroti Regional Referral Hospital in rural eastern Uganda. TB records from January 2017 to May 2024 were retrospectively reviewed to identify all PWH. MDR-TB was defined as resistance to at least both Isoniazid and Rifampicin following GeneXpert Mycobacterium TB and Rifampicin assay and culture-based drug-susceptible testing. Cases were PWH with MDR-TB, while controls were a random sample of PWH without MDR-TB, in a 1:3 ratio. Multivariable binary logistic regression was used to identify factors independently associated with being a case rather than a control. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were reported. Results: We included 37 cases and 111 controls, and found retreatment TB was associated with being a case rather than a control (aOR 6.97; 95% CI 2.65–19.46). Male sex (aOR: 1.59; 95% CI: 0.67–3.93), clinically diagnosed pulmonary TB (aOR: 0.38; 95% CI: 0.10–1.23) or extrapulmonary TB (aOR: 0.37; 95% CI: 0.05–1.62), and recent anti-retroviral therapy initiation (aOR: 2.07; 95% CI: 0.83–5.28) were insignificantly associated with being a case. Conclusion: This study showed that retreatment TB is associated with a higher likelihood of MDR-TB among PWH in a referral hospital in rural eastern Uganda. These findings underscore the need for intensified drug resistance surveillance and adherence support among PWH with prior TB treatment. Keywords: Multi-drug resistant tuberculosis, Human Immunodeficiency Virus, Previously treated tuberculosis, Retreatment TB, Uganda