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The CIDRZ Research Repository serves as an open-access archive for peer-reviewed publications, conference papers, and other scholarly outputs from CIDRZ researchers. Our goal is to promote the dissemination of knowledge and support evidence-based public health initiatives.
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Item Statistical Modelling of Waning Immunity After Shanchol Vaccination: A Prospective Cohort Study(Vaccines, 2026-01-30) Bosomprah, Samuel; Liswaniso, Fraser; Phiri, Bernard; Chibuye, Mwelwa; Luchen, Charlie C.; Ng’ombe, Harriet; Chibesa, Kennedy; Ngosa, Dennis; Muchimba, Mutinta; Debes, Amanda K.; Chilengi, Roma; Sack, David A.; Chisenga, Caroline C.Abstract Introduction: Cholera remains a major public health threat in endemic settings, and oral cholera vaccine (Shanchol™) campaigns are increasingly used amid constrained global supply. However, practical decisions on revaccination require clearer, setting-specific estimates of how rapidly vaccine-induced vibriocidal antibodies peak and wane. Methods: We conducted a prospective cohort kinetics analysis in Lukanga Swamps (Central Province, Zambia), enrolling adults (18–65 years) stratified by prior Shanchol™ exposure (0, 1, or 2 previous doses). All participants received two Shanchol™ doses 14 days apart, with serum collected at baseline and days 14, 28, 60, and 90 (end of follow-up). Ogawa and Inaba vibriocidal titres were measured using a complement-based assay and analysed on the log10 scale. Serotype-specific mixed-effects models with natural cubic splines for time (knots: 14, 28, 60 days) assessed trajectories by prior-dose strata, adjusting for age, sex, and HIV status. Peak timing and post-peak half-life were derived from model-based predictions with participant-level bootstrap CIs (1000 replications). Results: The analysis included 225 participants: 68 (30.2%) with zero prior doses, 89 (39.6%) with one, and 68 (30.2%) with two; median age was 33 years (IQR 25–49), 56.4% were female, and 19.2% were HIV-positive. Modelled titres for both serotypes rose steeply after vaccination, peaking around day 36–37 across prior-dose strata. Ogawa titres reached half of peak by about day 73–78, corresponding to post-peak half-lives of 37–41 days; Inaba declined more slowly with half-lives of 42–46 days. Confidence intervals overlapped across prior-dose strata, indicating minimal differences by vaccination history. Conclusions: In this cholera-endemic adult population, Shanchol™ induced vibriocidal responses that peaked at ~5 weeks and waned over the following 5–7 weeks, with broadly similar kinetics regardless of prior vaccination and slightly slower decay for Inaba than Ogawa. These parameters can inform booster timing in hotspot settings.Item Rotavirus Prevalence, Genetic Diversity, and Co-Infections during the 2023- 2024 Cholera Outbreak in Zambia: Insights from Multi-Pathogen Diagnostics(2026-02-28) Chauwa, Adriace; Bosomprah, Samuel; Phiri, Bernard; Laban, Natasha M.; Kuntawala, Dhvani H.; Ngosa, Dennis; Ng'ombe, Harriet; Liswaniso, Fraser; Luchen, Chaluma C.; Muchimba, Mutinta; Mwape, Innocent; Nzangwa, Bertha T.; Tigere, Sekayi F.; Chibesa, Kennedy; Silwamba, Suwilanji; Simuyandi, Michelo; Mbewe, Nyuma; Chilengi, Roma; Chisenga, Caroline C.Abstract During cholera outbreaks in Zambia, diagnostic strategies that rely on single-plex or targeted assays risk overlooking concomitant infections with other clinically important enteric pathogens. We estimated the prevalence of rotavirus and described co-detected enteropathogens and rotavirus genotypes among patients admitted with clinically suspected cholera during Zambia’s 2023–2024 cholera outbreak. We conducted a sub-analysis of diarrhoeal specimens collected from patients admitted to five cholera treatment centres who met the syndromic suspected cholera case definition. Stool samples were tested using the Bosphore® Gastroenteritis Panel v2, a multiplex PCR enteric panel, to detect rotavirus and other gastrointestinal pathogens. Rotavirus-positive specimen with sufficient viral load were further characterised by RT-PCR genotyping and Sanger sequencing targeting VP7 and VP4 genes. Among 319 suspected cholera admissions, rotavirus was detected in 18 patients, yielding a prevalence of 5.6% (95% CI 3.4%, 8.8%). Rotavirus detections occurred predominantly in children aged <5 years (87.5%) and 6-15 years (80.0%). Co-infection was common - 93.7%, (15/16) of rotavirus-positive samples showed co-infection with at least one additional enteric pathogen, primarily Campylobacter. Genotyping was successful in five samples and showed heterogenous circulating strains, including G1P[8], G2P[4], G3P[6], G12P[6], and a rare G1P[6] reassortant. During a large 2023–2024 cholera outbreak in Zambia, rotavirus accounted for a modest but clinically important fraction of the suspected cholera admissions and was typically identified within mixed enteric infections. These findings highlight the limitations of syndromic diagnosis in outbreak settings and support integrating multi-pathogen diagnostics and sustained molecular surveillance to improve case management, antimicrobial stewardship, and vaccine-era monitoring.Item Faecal Coliforms and Escherichia coli Contamination in Drinking Water Sources in Cholera Hotspot Areas of Lusaka District, Zambia: A Cross-Sectional Study(Microorganisms, 2026-02-11) Ng’ombe, Harriet; Luchen, Charlie C.; Phiri, Bernard; Ngosa, Dennis; Kapikila, Robby; Sakanya, Sydney; Sakala, Chikondi; Mbewe, Nyuma; Liswaniso, Fraser; Chilengi, Roma; Wilkinson, Eduan; Liebenberg, Lenine; Khan, Wesaal; Thomson, Nicholas R; Sack, David; Bosomprah, Samuel; Chisenga, Caroline C.Abstract The October 2023 to 2024 cholera outbreak demonstrates significant challenges related to water quality and sanitation, especially in peri-urban areas with limited access to clean water. This study assesses the presence of faecal coliforms and Escherichia coli (E. coli) in drinking water sources across five townships, identified as cholera transmission hotspots, two months post the cholera outbreak in the Lusaka District. A total of 169 water samples were collected from protected sources, treated piped water, and unprotected sources, including dams and shallow wells. Faecal coliforms and E. coli were detected across all source types. Among unprotected sources, 92.3% (12/13) of samples contained ≥100 CFU/100 mL of both faecal coliforms and E. coli. Protected sources showed variable contamination, with 18.3% exceeding ≥100 CFU/100 mL for faecal coliforms and 15.4% for E. coli. Treated water sources showed the lowest contamination, with 88.5% of samples having no detectable faecal coliforms and 90.4% having no detectable E. coli. Zero-inflated negative binomial regression showed that treated water sources were associated with substantially lower faecal coliform counts compared with protected sources (PR = 0.11, 95% CI: 0.03–0.35), while unprotected sources exhibited higher contamination intensity (PR = 1.77, 95% CI: 0.94–3.31). Treated sources were significantly more likely to be structurally free of contamination, whereas unprotected sources had an extremely low probability of yielding zero counts. These findings indicate that current water safety conditions in Lusaka’s cholera hotspot areas remain inadequate for preventing faecal-oral transmission.Item Genomic Analysis and Antimicrobial Resistance of Vibrio Cholerae Isolated During Zambia’s 2023 Cholera Epidemic(2025-12-02) Ng'ombe, Harriet; Luchen, Charlie C.; Bote, Lia; Kasonde, Mpanga; Musonda, Kunda; Mwape, Kapambwe K.; Kuntawala, Dhvani H.; Silwamba, Suwilanji; Chibuye, Mwelwa; Chibesa, Kennedy; Mbewe, Nyuma; Bosomprah, Samuel; Khan, Wesaal; Liebenberg, Lenine; Oliveira, Tulio de; Wilkinson, Eduan; Dorman, Matthew J.; Coghlan, Avril; Simuyandi, Michelo; Chilengi, Roma; Chisenga, Caroline; Thomson, Nicholas R.Introduction. Cholera, caused by Vibrio cholerae, remains a priority public health concern, particularly in developing countries. The first cholera outbreak in Zambia was documented in the 1970s, with recurring epidemics reported since then. In 2023, a cholera outbreak affected Zambia, particularly in districts bordering Malawi, Mozambique and the Democratic Republic of Congo, with significant cases reported in these neighbouring countries. This study aims to analyse cholera cases and isolates obtained during the 2023 epidemic, focusing on geographical distribution, genetic relatedness of isolates and their antibiotic resistance profiles. Methods. Stool samples were collected from patients presenting with cholera-like symptoms across three provinces of Zambia. A total of 98 samples were cultured on thiosulphate citrate bile salts sucrose agar, resulting in 32 sequenced V. cholerae isolates. Whole-genome sequencing was performed using Oxford Nanopore Technology, and phylogenetic inference was also achieved by the analysis of SNPs. Phenotypic antimicrobial resistance testing was conducted following Clinical and Laboratory Standards Institute guidelines. The genomic data were analysed for virulence factors and antimicrobial resistance profiles. Results. Of the 98 stool samples tested, 38 confirmed cholera cases were identified. A subset of 32 confirmed V. cholerae isolates, predominantly from the Eastern Province of Zambia (n=21), was selected for whole-genome sequencing. Genomic analysis revealed that all isolates belonged to the seventh pandemic El Tor lineage and the O1 serogroup, with two distinct clades identified corresponding to the 10th (T10) and 15th (T15) transmission events. Geographical analysis indicated a predominance of Ogawa serotypes in Eastern Province and Inaba in Northern Province. The virulence gene analysis confirmed the presence of key cholera toxin genes (ctxA and ctxB) and intestinal colonization factors. All isolates carried genes or mutations predicted to confer resistance to multiple antibiotics, including decreased susceptibility to ciprofloxacin, recommended for the treatment of cholera by the World Health Organization. Conclusion. The findings highlight the critical need for enhanced surveillance and targeted interventions to mitigate cholera outbreaks in Zambia. The emergence of resistant V. cholerae strains necessitates innovative strategies, including improved water sanitation, vaccination efforts and novel therapeutic approaches to combat this enduring public health threat.Item Prevalence and Patterns of Enteric Co-Infections Among Individuals Presenting with Cholera-like Diarrheal Disease During Seasonal Cholera Outbreaks(Pathogens, 2025-11-30) Kuntawala, Dhvani H.; Bosomprah, Samuel; Phiri, Bernard; Ng’ombe, Harriet; Liswaniso, Fraser; Muchimba, Mutinta; Silwamba, Suwilanji; Chibesa, Kennedy; Nzangwa, Bertha T.; Luchen, Charlie C.; Mwape, Innocent; Tigere, Sekayi F.; Simuyandi, Michelo; Mbewe, Nyuma; Chilengi, Roma; Debes, Amanda K.; Thomson, Nicholas R.; Sack, David A.; Chisenga, Caroline C.Abstract Cholera remains a major public health challenge, and co-infections can complicate clinical outcomes. In a cross-sectional study, we investigated the prevalence and patterns of enteric co-infections during Zambia’s 2023–2024 cholera outbreak and evaluated their implications for disease severity. 240 suspected cholera patients were enrolled from five healthcare facilities in Lusaka. Stools were tested for 11 enteric pathogens using the Bosphore® Gastroenteritis Panel Kit v2 on the QuantStudio 5 qPCR, with Vibrio cholerae confirmed by real-time PCR (quantitative PCR). Co-infections were highly prevalent, affecting 79.2% of participants. Campylobacter was the most frequently detected pathogen (70.0%), followed by Norovirus GI/GII (20.0%). Persons living with HIV were significantly more likely to present with co-infections than their counterparts (adjusted PR 1.27, 95% CI: 1.07–1.51; p = 0.008). Participants with confirmed V. cholerae + coinfections (N = 62) were less likely to developed moderate to severe disease compared to those with mono-infections (adjusted PR 0.59, 95% CI: 0.38–0.90; p = 0.014). These findings highlight the high prevalence and complexity of co-infections during cholera outbreaks, potentially contributing to antimicrobial resistance. They also highlight the need for targeted clinical management, particularly among persons living with HIV.Item Systematic review of associations between gut microbiome composition and stunting in under-five children.(2024-May-23) Chibuye, Mwelwa; Mende, Daniel R.; Spijker, Rene; Simuyandi, Michelo; Luchen, Chaluma C.; Bosomprah, Samuel; Chilengi, Roma; Schultsz, Constance; Harris, Vanessa C.Childhood stunting is associated with impaired cognitive development and increased risk of infections, morbidity, and mortality. The composition of the enteric microbiota may contribute to the pathogenesis of stunting. We systematically reviewed and synthesized data from studies using high-throughput genomic sequencing methods to characterize the gut microbiome in stunted versus non-stunted children under 5 years in LMICs. We included 14 studies from Asia, Africa, and South America. Most studies did not report any significant differences in the alpha diversity, while a significantly higher beta diversity was observed in stunted children in four out of seven studies that reported beta diversity. At the phylum level, inconsistent associations with stunting were observed for Bacillota, Pseudomonadota, and Bacteroidota phyla. No single genus was associated with stunted children across all 14 studies, and some associations were incongruent by specific genera. Nonetheless, stunting was associated with an abundance of pathobionts that could drive inflammation, such as Escherichia/Shigella and Campylobacter, and a reduction of butyrate producers, including Faecalibacterium, Megasphera, Blautia, and increased Ruminoccoccus. An abundance of taxa thought to originate in the oropharynx was also reported in duodenal and fecal samples of stunted children, while metabolic pathways, including purine and pyrimidine biosynthesis, vitamin B biosynthesis, and carbohydrate and amino acid degradation pathways, predicted linear growth. Current studies show that stunted children can have distinct microbial patterns compared to non-stunted children, which could contribute to the pathogenesis of stunting.Item Evaluating a multifaceted implementation strategy and package of evidence-based interventions based on WHO PEN for people living with HIV and cardiometabolic conditions in Lusaka, Zambia: protocol for the TASKPEN hybrid effectiveness-implementation stepped wedge cluster randomized trial.(2024-Jun-06) Herce, Michael E.; Bosomprah, Samuel; Masiye, Felix; Mweemba, Oliver; Edwards, Jessie K.; Mandyata, Chomba; Siame, Mmamulatelo ; Mwila, Chilambwe; Matenga, Tulani; Frimpong, Christiana ; Mugala, Anchindika; Mbewe, Peter; Shankalala, Perfect; Sichone, Pendasambo; Kasenge, Blessings; Chunga, Luanaledi ; Adams, Rupert; Banda, Brain; Mwamba, Daniel; Nachalwe, Namwinga; Agarwal, Mansi; Williams, Makeda J.; Tonwe, Veronica; Pry, Jake M.; Musheke, Maurice; Vinikoor, Michael; Mutale, WilbroadBACKGROUND: Despite increasing morbidity and mortality from non-communicable diseases (NCD) globally, health systems in low- and middle-income countries (LMICs) have limited capacity to address these chronic conditions, particularly in sub-Saharan Africa (SSA). There is an urgent need, therefore, to respond to NCDs in SSA, beginning by applying lessons learned from the first global response to any chronic disease-HIV-to tackle the leading cardiometabolic killers of people living with HIV (PLHIV). We have developed a feasible and acceptable package of evidence-based interventions and a multi-faceted implementation strategy, known as "TASKPEN," that has been adapted to the Zambian setting to address hypertension, diabetes, and dyslipidemia. The TASKPEN multifaceted implementation strategy focuses on reorganizing service delivery for integrated HIV-NCD care and features task-shifting, practice facilitation, and leveraging HIV platforms for NCD care. We propose a hybrid type II effectiveness-implementation stepped-wedge cluster randomized trial to evaluate the effects of TASKPEN on clinical and implementation outcomes, including dual control of HIV and cardiometabolic NCDs, as well as quality of life, intervention reach, and cost-effectiveness. METHODS: The trial will be conducted in 12 urban health facilities in Lusaka, Zambia over a 30-month period. Clinical outcomes will be assessed via surveys with PLHIV accessing routine HIV services, and a prospective cohort of PLHIV with cardiometabolic comorbidities nested within the larger trial. We will also collect data using mixed methods, including in-depth interviews, questionnaires, focus group discussions, and structured observations, and estimate cost-effectiveness through time-and-motion studies and other costing methods, to understand implementation outcomes according to Proctor's Outcomes for Implementation Research, the Consolidated Framework for Implementation Research, and selected dimensions of RE-AIM. DISCUSSION: Findings from this study will be used to make discrete, actionable, and context-specific recommendations in Zambia and the region for integrating cardiometabolic NCD care into national HIV treatment programs. While the TASKPEN study focuses on cardiometabolic NCDs in PLHIV, the multifaceted implementation strategy studied will be relevant to other NCDs and to people without HIV. It is expected that the trial will generate new insights that enable delivery of high-quality integrated HIV-NCD care, which may improve cardiovascular morbidity and viral suppression for PLHIV in SSA. This study was registered at ClinicalTrials.gov (NCT05950919).Item Diagnostic accuracy of saliva-based testing as a Vibrio cholerae surveillance tool among naturally infected patients.(2025-Jan-21) Chisenga, Caroline C.; Phiri, Bernard; Ng'ombe, Harriet; Muchimba, Mutinta; Liswaniso, Fraser; Bernshtein, Biana; Cunningham, Adam F.; Sack, David; Bosomprah, SamuelSaliva, as a diagnostic medium, offers a promising alternative to blood by virtue of its non-invasive collection, which enhances patient compliance, especially in paediatric and geriatric populations. In this study, we assessed the utility of saliva as a non-invasive medium for measuring Vibrio cholerae-specific serum antibodies in naturally infected individuals. We tested paired serum and saliva samples obtained from a total of 63 patients with cholera enrolled in a cohort study. Vibriocidal antibodies assay (IgM/IgG) as markers for accurate determination was used to determine cholera-specific antibody levels. Using receiver operating characteristics (ROC) curve, we found that the best cut-off that maximizes (sensitivity + specificity) is 10 titres. At this saliva titre, the sensitivity is 76.9% (95%CI: 60.9%, 87.7%) and specificity is 80.0% (95%CI: 56.6%, 92.5%). Using Spearman's correlation coefficient, we also found evidence of a positive correlation between V. cholerae saliva and serum antibodies (rho = 0.66, P < 0.001). In conclusion, saliva-based diagnostic cholera tests have high diagnostic accuracy and would be advantageous, cheaper, and quicker for early diagnosis of severe cholera outcomes.Item Cohort profile: Noncommunicable diseases and ideal cardiovascular health among people living with and without HIV in Zambia and Zimbabwe (NCDzz cohort).(2025-Feb-07) Chihota, Belinda V.; Mandiriri, Ardele; Muula, Guy; Banda, Esau; Shamu, Tinei; Bolton-Moore, Carolyn; Chimbetete, Cleophas; Bosomprah, Samuel; Wandeler, GillesPURPOSE: The NCDzz study is a prospective cohort of people living with and without HIV attending primary care clinics in Zambia and Zimbabwe and was established in 2019 to understand the intersection between noncommunicable diseases (NCDs) and HIV in Southern Africa. Here, we describe the study design and population and evaluate their ideal cardiovascular health (ICVH) using the Life's Simple 7 (LS7) score according to the American Heart Association. PARTICIPANTS: Antiretroviral therapy-naïve people living with HIV (PLWH) and people living without HIV (PLWOH) 30 years or older were recruited from three primary care clinics in Lusaka and Harare, and underwent comprehensive clinical, laboratory and behavioural assessments. All study measurements are repeated during yearly follow-up visits. PLWOH were recruited from the same neighbourhoods and had similar socioeconomic conditions as PLWH. FINDINGS TO DATE: Between August 2019 and March 2023, we included 1100 adults, of whom 618 (56%) were females and 539 (49%) were PLWH. The median age at enrolment was 39 years (IQR 34-46 years). Among 1013 participants (92%) with complete data, the median LS7 score was 11/14 (IQR 10-12). Overall, 60% of participants met the criteria of ICVH metrics (5-7 ideal components) and among individual components of the LS7, more females had poor body mass index (BMI) than males, regardless of HIV status (27% vs 3%, p<0.001). Our data show no apparent difference in cardiovascular health determinants between men and women, but high BMI in women and overall high hypertension prevalence need detailed investigation. Untreated HIV (OR: 1.36 (IQR 1.05-1.78)) and being a Zambian participant (OR: 1.81 (IQR 1.31-2.51)) were associated with having ICVH metrics, whereas age older than 50 years (OR: 0.46 (IQR 0.32-0.65)) was associated with not having ICVH metrics. FUTURE PLANS: Our study will be regularly updated with upcoming analyses using prospective data including a focus on arterial hypertension and vascular function. We plan to enrich the work through conducting in-depth assessments on the determinants of cardiovascular, liver and kidney end-organ disease outcomes yearly. Additionally, we seek to pilot NCD interventions using novel methodologies like the trials within cohorts. Beyond the initial funding support, we aim to collect at minimum yearly data for an additional 5-year period.Item Prevalence of hypertension and its treatment among adults presenting to primary health clinics in rural Zambia: analysis of an observational database.(2015-Sep-21) Yan, Lily D.; Chi, Benjamin H.; Sindano, Ntazana; Bosomprah, Samuel; Stringer, Jeffrey S.; Chilengi, RomaBACKGROUND: Hypertension constitutes a growing burden of illness in developing countries like Zambia. Adequately screening and treating hypertension could greatly reduce the complications of stroke and coronary disease. Our objective was to determine the prevalence of hypertension and identify current treatment practices among adult patients presenting for routine care to rural health facilities in the Better Health Outcomes through Mentoring and Assessments (BHOMA) project. METHODS: We conducted a retrospective analysis of routinely collected clinical data from 46 rural government clinics in Zambia. Our analysis cohort comprised patients ≥ 25 years with recorded blood pressure measurements, who sought care at primary health centers. Consistent with prior research, in our primary analysis, we only included data from first visits. Hypertension was defined as a systolic blood pressure ≥140 mmHg, or diastolic blood pressure ≥90 mmHg, or reported use of antihypertensive medication. A sensitivity analysis was performed using median blood pressure for individuals with multiple visits. RESULTS AND DISCUSSION: From January 2011 to December 2014, 116,130 first visits by adult patients met eligibility criteria. The crude prevalence of hypertension by onsite measurement or reported use of antihypertensive medication was 23.1% [95% CI: 22.8-23.3] (23.6% in females, 22.3% in males). The age standardized prevalence of hypertension across participating sites was 28.0 [95% CI: 27.7-28.3] (29.7% in females, 25.8% in males). Sensitivity analysis revealed a similar prevalence using data from all visits. Only 5.6% of patients had a diagnosis of hypertension documented in their medical record. Among patients with hypertension, only 18.0% had any antihypertensive drug prescribed, with nifedipine (8.9%), furosemide (8.3%), and propranolol (2.4%) as the most common. CONCLUSIONS: Age standardized prevalence of hypertension in rural primary health clinics in Zambia was high compared to other studies in rural Africa; however, we diagnosed hypertension with only one measurement and this may have biased our findings. Future efforts to improve hypertension control should focus on population preventive care and primary healthcare provider education on individual management.