Browsing by Author "Ngosa, Dennis"

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Assessing courtesy reporting bias in facility-based surveys on person-centred maternity care: evidence from urban informal settlements in Nairobi and Lusaka.
(2025-Mar-28) Jiwani, Safia S.; Mutua, Martin K.; Jacobs, Choolwe; Musukuma Mwiche; Njeri, Anne; Adero, Godfrey; Ngosa, Dennis; Abajobir, Amanuel; Faye, Cheikh M.; Boerma, Ties; Amouzou, Agbessi
BACKGROUND: Experience of care is typically measured through client exit surveys administered in the facility. Evidence suggests that such measures suffer from courtesy reporting bias whereby respondents do not accurately report on their experiences while in the facility. We explored the presence of courtesy bias by comparing women's reported experience of person-centred maternity care (PCMC) from facility-based client exit surveys to mobile phone-based surveys out of the facility in Nairobi and Lusaka's urban informal settlements. METHODS: We randomly and independently sampled women in the facilities for either a facility-based survey (n = 233 in Lusaka and n = 112 in Nairobi) or a mobile phone-based survey (n = 203 in Lusaka and n = 300 in Nairobi) within one to two weeks of facility discharge. The questionnaire included a validated PCMC scale. After adjusting for differences in women's characteristics across groups, we compared PCMC scores between facility and phone-based samples. We ran multilevel linear regression models to assess PCMC by survey modality in each city. RESULTS: In both cities, over 70.0% of women were aged 20-34 years and were married, at least two thirds had secondary education, and over 95.0% were unaccompanied during labour/delivery. The overall PCMC score was 69.3% among women surveyed on the phone compared to 70.2% among those surveyed in the facility in Nairobi. In Lusaka, it was 57.5% on the phone compared to 56.8% in-facility. We found no statistically significant differences in PCMC scores between survey modalities in both cities, after adjusting for differences in women's characteristics. CONCLUSIONS: We did not detect significant courtesy reporting bias in PCMC in facility-based client exit surveys in the context of urban informal settlements in Nairobi and Lusaka. Experience of PCMC can be measured through in-facility client exit surveys or mobile phone surveys. However, it is critical to address challenges related to a mobile phone-based approach.
Childhood tuberculosis outcomes and factors associated with unsuccessful treatment outcomes in selected public hospitals of Lusaka Zambia from 2015 to 2019.
(2024) Ngosa, Dennis; Lupenga, Joseph
Treatment outcomes of tuberculosis in children are rarely evaluated. Childhood tuberculosis has been a low priority for tuberculosis programs due to difficulties in diagnosis and treatment. This study evaluated childhood tuberculosis outcomes and factors associated with unsuccessful treatment outcomes in selected public hospitals in Lusaka, Zambia from 2015 to 2019. This was a cross-sectional study conducted in eight public hospitals in Lusaka. All children aged 0-14 years, treated with tuberculosis and had treatment outcomes evaluated were included. The WHO tuberculosis treatment outcomes were grouped into successful treatment outcome (cured, treatment completed) and unsuccessful treatment outcome (death, loss to follow-up, failure). Taking unsuccessful treatment outcome as the outcome variable, logistic regression models were performed. All analyses were done at a 95% confidence interval. Out of 2,531 children managed for TB from 2015 to 2019, only 1,495 (59.1%) had treatment outcomes evaluated. Out of 1,495 participants, majority were 5 to 14 years old (50.9%), males (51.1%), HIV-negative (58.7%), and had pulmonary tuberculosis (74.2%). Bacteriological tests were performed on 59.8% of children, where 21.6% had positive bacteriological results. Bacteriologically confirmed TB was higher in children over 5 years (29.5%), pulmonary TB (25.6%), and retreatment (28.6%). The majority of children (84.2%) completed treatment, while 10.7% were cured, 1.5% were lost to follow-up, 3.1% died, and 0.5% failed treatment. Overall, unsuccessful treatment outcome was 5.1% while successful treatment outcome was 94.1%. Extrapulmonary tuberculosis was associated with unsuccessful treatment outcomes (AOR 1.64; 95% CI: 1.02-2.62). The tuberculosis successful treatment outcome met the World Health Organization's threshold goal of 90%. Children with extrapulmonary tuberculosis should be targeted as a high-risk group to improve treatment outcomes. Tracking children whose treatment outcomes were not evaluated would provide more precise estimates of TB treatment outcomes.
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.
Levels and determinants of person-centred maternity care among women living in urban informal settlements: evidence from client exit surveys in Nairobi, Lusaka and Ouagadougou.
(2025-Mar-15) Jiwani, Safia S.; Cissé, Kadari; Mutua, Martin K.; Jacobs, Choolwe; Njeri, Anne; Adero, Godfrey; Musukuma, Mwiche; Ngosa, Dennis; Sissoko, Fatou B.; Kouanda, Seni; Abajobir, Amanuel ; Faye, Cheikh M.; Boerma, Ties; Amouzou, Agbessi
BACKGROUND: Sub-Saharan Africa's rapid urbanisation has led to the sprawling of urban informal settlements. The urban poorest women are more likely to experience worse health outcomes and poor treatment during childbirth. This study measures levels of person-centred maternity care (PCMC) and identifies determinants of PCMC among women living in urban informal settlements in Nairobi, Lusaka and Ouagadougou. METHODS: We conducted phone, home-based or facility-based exit surveys of women discharged from childbirth care in facilities serving urban informal settlements. We estimated overall and domain-specific PCMC scores covering dignity and respect, communication and autonomy, and supportive care. We ran multilevel linear regression models to identify structural, intermediary and health systems factors associated with PCMC. RESULTS: We included 1249 women discharged from childbirth care: the majority were aged 20-34 years and were unemployed. In Lusaka and Nairobi, over 65% of women had secondary education, and over half gave birth in a hospital, whereas in Ouagadougou one-third had secondary education and 30.4% gave birth in a hospital. The mean PCMC score ranged from 57.1% in Lusaka to 73.8% in Ouagadougou. Across cities, women reported high dignity and respect mean scores (73.5%-84.3%), whereas communication and autonomy mean scores were consistently poor (47.6%-63.2%). In Ouagadougou, women with formal employment, those who delivered in a private for-profit facility, and whose newborn received postnatal care before discharge reported significantly higher PCMC. In Nairobi and Lusaka, women who were attended by a physician during childbirth, and those whose newborn was checked before discharge reported significantly higher PCMC. CONCLUSIONS: Women living in urban informal settlements experience inadequate PCMC and report poor communication with health providers. Select health systems and provision of care factors are associated with PCMC in this context. Quality improvement efforts are needed to enhance PCMC and ensure women's continuity in care seeking.
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.
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.