Under-5 mortality surveillance in low-income and middle-income countries: insights from two Health and Demographic Surveillance Systems in rural Gambia.

Without complete data on under-5 mortality, tracking progress towards achieving Sustainable Development Goal 3.2 will be challenging. Such data are also needed to ensure proper planning and prioritisation of scarce resources in low-income and middle-income countries. However, most low-income and middle-income countries have weak Civil Registration and Vital Statistics (CRVS) systems, leaving a critical gap in understanding under-5 mortality dynamics. This paper outlines a community-based approach to enhance under-5 mortality surveillance in low-income countries, using The Gambia as a case study. The methodology involves Health and Demographic Surveillance Systems (HDSSs) in Basse and Fuladu West, employing unique identification numbers, periodical household visits and collaboration with communities, village reporters and project field workers to ensure comprehensive data collection. Verbal autopsies (VAs) are conducted by trained field workers, and causes of death are determined using the physician-certified VA method. Between 1 September 2019 and 1 September 2023, 1333 deaths were detected, for which causes of death were determined for 97.1% (1294 of 1333). The most common causes of death detected were acute respiratory infections including pneumonia, sepsis, diarrhoeal diseases and birth asphyxia. Challenges include the cost of maintaining the HDSSs, poor road infrastructure, Electronic Data Capture transition challenges, and the need for national integration of HDSS data into the CRVS system. The success of this model highlights its potential for scalable and adaptable under-5 mortality surveillance in resource-limited settings.

The effect of physical barriers under a raised house on mosquito entry: an experimental study in rural Gambia.

BACKGROUND: Anopheles gambiae, the major malaria mosquito in sub-Saharan Africa, feed largely indoors at night. Raising a house off the ground with no barriers underneath reduces mosquito-house entry. This experiment tested whether walling off the space under an elevated hut affects mosquito-hut entry. METHODS: Four inhabited experimental huts, each of which could be moved up and down, were used in rural Gambia. Nightly collections of mosquitoes were made using light traps and temperature and carbon dioxide levels monitored indoors and outdoors using loggers. Each night, a reference hut was kept at ground level and three huts raised 2 m above the ground; with the space under the hut left open, walled with air-permeable walls or solid walls. Treatments were rotated every four nights using a randomized block design. The experiment was conducted for 32 nights. Primary measurements were mosquito numbers and indoor temperature in each hut. RESULTS: A total of 1,259 female Anopheles gambiae sensu lato were collected in the hut at ground level, 655 in the hut with an open ground floor, 981 in the hut with air-permeable walls underneath and 873 in the hut with solid walls underneath. Multivariate analysis, adjusting for confounders, showed that a raised hut open underneath had 53% fewer mosquitoes (95% CI 47-58%), those with air-permeable walls underneath 24% fewer (95% CI 9-36%) and huts with solid walls underneath 31% fewer (95% CI 24-37%) compared with a hut on the ground. Similar results were found for Mansonia spp. and total number of female mosquitoes, but not for Culex mosquitoes where hut entry was unaffected by height or barriers. Indoor temperature and carbon dioxide levels were similar in all huts. CONCLUSION: Raising a house 2 m from the ground reduces the entry of An. gambiae and Mansonia mosquitoes, but not Culex species. The protective effect of height is reduced if the space underneath the hut is walled off.

Comprehensive HIV knowledge and associated factors among reproductive-age women: analysis of the Gambia Demographic and Health Survey 2019/2020.

INTRODUCTION: Globally, there are 37.7 million people living with human immunodeficiency virus (HIV). So far, there is no study done in Gambia which assessed comprehensive HIV knowledge and its associated factors. Therefore, this study aims to assess comprehensive HIV knowledge and its associated factors among reproductive-age women in Gambia. OBJECTIVE: To assess the prevalence of comprehensive HIV knowledge and its associated factors among reproductive-age women in Gambia. METHODS: The study used the Gambian Demographic and Health Survey, which was conducted from 21 November 2019 to 30 March 2020 in Gambia. The survey employed a stratified two-stage cluster sampling technique to recruit study participants. Logistic regression analysis was used to identify factors associated with HIV comprehensive knowledge. Statistical significance was declared at a P value of less than 0.05 with a 95% confidence interval (CI). RESULTS: The overall prevalence of comprehensive HIV knowledge was 27.1% (25.1-36.2%). Older age [adjusted odds ratio (AOR) of 1.20 (95% CI 1.16-1.26)], using contraceptive [AOR of 1.15 (95% CI 1.01-1.31)], higher education [AOR of 4.73 (95% CI 3.86-5.81)], rich wealth quintile [AOR of 1.61 (95% CI 1.37-1.87)], media exposure [AOR of 1.76 (95% CI 1.39-2.23)], ever tested for HIV [AOR of 1.55 (95% CI 1.42-1.74)], visited health facility within the last 12 months [AOR of 1.26 (95% CI 1.12-1.41)] and decision-making autonomy [AOR of 1.42 (95% CI 1.27-1.60)] were positively associated with comprehensive HIV knowledge. However, being married [AOR of 0.72 (95% CI 0.62-0.82)] was negatively associated with comprehensive HIV knowledge. CONCLUSIONS: The prevalence of comprehensive HIV knowledge was low in Gambia. Educational interventions that focused mainly on awareness creation about HIV/AIDS should be designed especially for married women and lower socio-economic status. An effort has to be made to address those disparities at the national level.

Haem iron versus ferrous iron salts to treat iron deficiency anaemia in Gambian children: protocol for randomised controlled trial {1}.

BACKGROUND: The World Health Organization recommends universal iron supplementation for children aged 6-23 months in countries where anaemia is seen in over 40% of the population. Conventional ferrous salts have low efficacy due to low oral absorption in children with inflammation. Haem iron is more bioavailable, and its absorption may not be decreased by inflammation. This study aims to compare daily supplementation with haem iron versus ferrous sulphate on haemoglobin concentration and serum ferritin concentration after 12 weeks of supplementation. METHODS: This will be a two-arm, randomised controlled trial. Gambian children aged 6-12 months with anaemia will be recruited within a predefined geographical area and recruited by trained field workers. Eligible participants will be individually randomised using a 1:1 ratio within permuted blocks to daily supplementation for 12 weeks with either 10.0 mg of elemental iron as haem or ferrous sulphate. Safety outcomes such as diarrhoea and infection-related adverse events will be assessed daily by the clinical team (see Bah et al. Additional file 4_Adverse event eCRF). Linear regression will be used to analyse continuous outcomes, with log transformation to normalise residuals as needed. Binary outcomes will be analysed by binomial regression or logistic regression, Primary analysis will be by modified intention-to-treat (i.e., those randomised and who ingested at least one supplement dose of iron), with multiple imputations to replace missing data. Effect estimates will be adjusted for baseline covariates (C-reactive protein, alpha-1-acid glycoprotein, haemoglobin, ferritin, soluble transferrin receptor). DISCUSSION: This study will determine if therapeutic supplementation with haem iron is more efficacious than with conventional ferrous sulphate in enhancing haemoglobin and ferritin concentrations in anaemic children aged 6-12 months. TRIAL REGISTRATION: Pan African Clinical Trial Registry PACTR202210523178727.

Exposure to pro-tobacco and anti-tobacco media messages and events and smoking behaviour among adolescents in Gambia.

BACKGROUND: Despite the widespread prevalence of adolescent smoking in Gambia, a West African country, there is limited research exploring the relationships between exposure to pro-tobacco and anti-tobacco media messages and events and smoking behaviour among young people. This study investigates the interplay of these exposures and smoking behaviour among 11-17-year-old adolescents in Gambia. METHODS: Secondary data analysis was conducted using the 2017 Gambia Global Youth and Tobacco Survey (GYTS), which included a total of 9,127 respondents. Descriptive and inferential analyses, including proportions, Pearson's chi-squared tests, and multivariable logistic regression models, were employed to estimate adjusted odds ratios (aOR) with 95% confidence intervals (CI). RESULTS: The final model revealed significant associations between exposure to anti-tobacco media messages and events and smoking behaviour. Adolescents exposed to anti-tobacco media messages had a 29% increased odds of smoking (aOR 1.29,CI = 1.08,1.53) compared to those unexposed, while exposure to anti-tobacco media events showed a 31% increased odds (aOR 1.31,CI = 1.09,1.59) compared to those unexposed. Exposure to pro-tobacco messages, such as witnessing tobacco use on TV (aOR 1.41, CI = 1.17,1.69) and owning objects with tobacco brand logos (aOR 1.49,CI = 1.19,1.86), was associated with higher odds of smoking. Covariates, including sex, age, and exposure to smoking behaviour by significant others, also demonstrated associations with smoking behaviour. Notably, male respondents showed significantly higher odds of smoking (aOR = 4.01,CI = 3.28,4.89) compared to females. Respondents aged 15 years and older had increased odds of smoking (aOR = 1.47,CI = 1.22,1.76) compared to those below 15 years old. Those whose fathers smoke displayed higher odds of smoking (aOR = 1.35, CI = 1.04,1.76) compared to individuals with non-smoking parents. Additionally, those whose closest friends smoke showed remarkably higher odds of smoking (aOR = 2.87,CI = 2.37, 3.48) compared to those without such influence. CONCLUSION: This study underscores the significant impact of exposure to both anti-tobacco and pro-tobacco media messages and events on smoking behaviour among adolescents in Gambia. However, pro-tobacco messages had a greater influence on smoking prevalence than anti-tobacco messages and events. Understanding these associations is crucial for devising effective public health interventions aimed at reducing tobacco use in this population.

Assessing the impact of a cleaning programme on environmental hygiene in labour and neonatal wards: an exploratory study in The Gambia.

BACKGROUND: Effective surface cleaning in hospitals is crucial to prevent the transmission of pathogens. However, hospitals in low- and middle-income countries face cleaning challenges due to limited resources and inadequate training. METHODS: We assessed the effectiveness of a modified TEACH CLEAN programme for trainers in reducing surface microbiological contamination in the newborn unit of a tertiary referral hospital in The Gambia. We utilised a quasi-experimental design and compared data against those from the labour ward. Direct observations of cleaning practices and key informant interviews were also conducted to clarify the programme's impact. RESULTS: Between July and September 2021 (pre-intervention) and October and December 2021 (post-intervention), weekly surface sampling was performed in the newborn unit and labour ward. The training package was delivered in October 2021, after which their surface microbiological contamination deteriorated in both clinical settings. While some cleaning standards improved, critical aspects such as using fresh cleaning cloths and the one-swipe method did not. Interviews with senior departmental and hospital management staff revealed ongoing challenges in the health system that hindered the ability to improve cleaning practices, including COVID-19, understaffing, disruptions to water supply and shortages of cleaning materials. CONCLUSIONS: Keeping a hospital clean is fundamental to good care, but training hospital cleaning staff in this low-income country neonatal unit failed to reduce surface contamination levels. Further qualitative investigation revealed multiple external factors that challenged any possible impact of the cleaning programme. Further work is needed to address barriers to hospital cleaning in low-income hospitals.

The use of Kudoh method for culture of Mycobacterium tuberculosis and Mycobacterium africanum in The Gambia.

BACKGROUND: Mycobacterium tuberculosis culturing remains the gold standard for laboratory diagnosis of tuberculosis. Tuberculosis remains a great public health problem in developing countries like The Gambia, as most of the methods currently used for bacterial isolation are either time-consuming or costly. OBJECTIVE: To evaluate the Kudoh swab method in a West African setting in Gambia, with a particular focus on the method's performance when culturing Mycobacterium africanum West Africa 2 (MAF2) isolates. METHOD: 75 sputum samples were collected in the Greater Banjul Area and decontaminated in parallel with both the standard N-acetyl-L-Cysteine-NaOH (NALC-NaOH) and the Kudoh swab method in the TB diagnostics laboratory in the Medical Research Council Unit The Gambia between 30th December 2017 and 25th February 2018. These samples were subsequently cultured on standard Löwenstein-Jensen and Modified Ogawa media respectively and incubated at 37°C for mycobacterial growth. Spoligotyping was done to determine if the decontamination and culture methods compared could equally detect Mycobacterium tuberculosis, Mycobacterium africanum West Africa 1 and Mycobacterium africanum West Africa 2. RESULT: Among the 50 smear positives, 35 (70%) were culture-positive with Kudoh and 32 (64%) were culture positive with NALC-NaOH, whilst 7(28%) of the 25 smear negative samples were culture positive with both methods (Table 2). There was no significant difference in recovery between both methods (McNemar's test, p-value = 0.7003), suggesting that the overall positivity rate between the two methods is comparable. There were no differences in time-to-positivity or contamination rate between the methods. However, Kudoh yielded positive cultures that were negative on LJ and vice versa. All findings were irrespective of mycobacterial lineages. CONCLUSION: The Kudoh method has comparable sensitivity to the NALC-NaOH method for detecting Mycobacterium tuberculosis complex isolates. It is easy to perform and could be an add on option for mycobacterial culture in the field in The Gambia, since it requires less biosafety equipment.

Genomic insights into local-scale evolution of ocular Chlamydia trachomatis strains within and between individuals in Gambian trachoma-endemic villages.

Trachoma, a neglected tropical disease caused by Chlamydia trachomatis (Ct) serovars A-C, is the leading infectious cause of blindness worldwide. Africa bears the highest burden, accounting for over 86 % of global trachoma cases. We investigated Ct serovar A (SvA) and B (SvB) whole genome sequences prior to the induction of mass antibiotic drug administration in The Gambia. Here, we explore the factors contributing to Ct strain diversification and the implications for Ct evolution within the context of ocular infection. A cohort study in 2002-2003 collected ocular swabs across nine Gambian villages during a 6 month follow-up study. To explore the genetic diversity of Ct within and between individuals, we conducted whole-genome sequencing (WGS) on a limited number (n=43) of Ct-positive samples with an omcB load ≥10 from four villages. WGS was performed using target enrichment with SureSelect and Illumina paired-end sequencing. Out of 43 WGS samples, 41 provided sufficient quality for further analysis. ompA analysis revealed that 11 samples had highest identity to ompA from strain A/HAR13 (NC_007429) and 30 had highest identity to ompA from strain B/Jali20 (NC_012686). While SvB genome sequences formed two distinct village-driven subclades, the heterogeneity of SvA sequences led to the formation of many individual branches within the Gambian SvA subclade. Comparing the Gambian SvA and SvB sequences with their reference strains, Ct A/HAR13 and Ct B/Jali20, indicated an single nucleotide polymorphism accumulation rate of 2.4×10-5 per site per year for the Gambian SvA and 1.3×10-5 per site per year for SvB variants (P<0.0001). Variant calling resulted in a total of 1371 single nucleotide variants (SNVs) with a frequency >25 % in SvA sequences, and 438 SNVs in SvB sequences. Of note, in SvA variants, highest evolutionary pressure was recorded on genes responsible for host cell modulation and intracellular survival mechanisms, whereas in SvB variants this pressure was mainly on genes essential for DNA replication/repair mechanisms and protein synthesis. A comparison of the sequences between observed separate infection events (4-20 weeks between infections) suggested that the majority of the variations accumulated in genes responsible for host-pathogen interaction such as CTA_0166 (phospholipase D-like protein), CTA_0498 (TarP) and CTA_0948 (deubiquitinase). This comparison of Ct SvA and SvB variants within a trachoma endemic population focused on their local evolutionary adaptation. We found a different variation accumulation pattern in the Gambian SvA chromosomal genes compared with SvB, hinting at the potential of Ct serovar-specific variation in diversification and evolutionary fitness. These findings may have implications for optimizing trachoma control and prevention strategies.

Impact of pneumococcal conjugate vaccination on pneumococcal nasopharyngeal carriage in the Gambia: Population-based cross-sectional surveys.

BACKGROUND: The introduction of pneumococcal conjugate vaccines (PCV) has reduced carriage of vaccine-type (VT) pneumococci in many settings. We determined the impact of The Gambia's national PCV programme on carriage of VT pneumococci in the population. METHODS: Seven-valent PCV (PCV7) was introduced in August 2009 without catch-up and with doses scheduled at 2, 3, 4 months of age; it was replaced by PCV13 in May 2011. We did cross-sectional carriage surveys in 2009, 2015, and 2017 in age-stratified, population-based samples. Nasopharyngeal specimens were collected and processed according to WHO guidelines. We calculated observed and adjusted prevalence ratios (PR) of VT carriage before and after PCV introduction. FINDINGS: We enrolled 2988, 3162, and 2709 participants in 2009, 2015, and 2017 respectively. The baseline (2009) prevalence of VT pneumococcal carriage among children aged 0-4 years was 42.6 %, which declined to 14.9 % and 17.5 % in 2015 and 2017 respectively (adjPR 0.32 [95 % CI 0.27, 0.38] and 0.38 [0.31, 0.46] respectively). VT prevalence among children aged 5-14 years was 16.6 %, 15.1 %, and 15.8 % in the three surveys (2017 vs 2009, adjPR 0.70 [0.58, 0.83]). VT prevalence among 15-44 year-olds was 6.4 %, 5.7 %, and 7.1 % in the three surveys (2017 vs 2009, adjPR 0.59 [0.46, 0.75]), while in those aged ≥ 45 years it was 4.5 %, 6.5 %, and 4.5 % respectively. Non-VT carriage increased in all age-groups. Prevalent residual serotypes were 34 and 15B (age 0-4 years), 3 and 34 (age 5-14 years), and 3 and 16F (age ≥ 15 years). CONCLUSIONS: Introduction of PCV was associated with reduced VT pneumococcal carriage in young, and older children, although with substantial residual prevalence. Persisting VT, and non-VT, carriage indicate significant, persistent transmission of pneumococci in the population.

'It's about time': policymakers' and health practitioners' perspectives on implementing fertility care in the Gambian health system.

BACKGROUND: Infertility is a major health issue worldwide, yet very few examples of interventions addressing infertility in the Global South have been documented to date. In The Gambia, West Africa, infertility is recognised as a burden and the health authorities have included it in several health policies and the new National Reproductive Health Strategy however, a detailed operationalisation plan for fertility care has not yet been established. Here, we aim to understand and document the factors that influence the implementation of fertility care in The Gambia. METHODS: We conducted 46 semi-structured interviews with policymakers, implementers, and health practitioners in both the public and private sectors from July to November 2021. The interviews were transcribed, anonymised and analysed with NVivo Pro version 1.6.1. The analysis was initially inductive, with themes arising from the coding categorised according to the WHO health systems building blocks framework. RESULTS: This study identified several barriers to a successful implementation of fertility care in The Gambia, including (i) a lack of routinely collected infertility data; (ii) an absence of financial protection mechanisms for patients, and/or a specific budget for infertility; (iii) limited cooperation between the public and private sectors in the provision of fertility care; and (iv) gaps in fertility care training among health practitioners. Conversely, enablers included: (i) strong national infertility leadership; and (ii) the integration of infertility care within public reproductive health services. CONCLUSION: The Gambian health system is not yet in the position to support a comprehensive fertility care package in its public health facilities. Several aspects of the implementation of fertility care must be considered in operationalising the health strategy including the systematic collection of infertility data, fertility awareness, and the provision of specialised fertility care training. Furthermore, a stronger partnership between the public and private sectors must be developed. Given the increasing availability of assisted reproductive technologies in the sub-Saharan Africa region, and the tendency to locate these technologies in the private sector, further research is needed to understand and identify the processes underlying the implementation of fertility care and to foster better integration with the existing health system.

Safety of the novel oral poliovirus vaccine type 2 (nOPV2) in infants and young children aged 1 to <5 years and lot-to-lot consistency of the immune response to nOPV2 in infants in The Gambia: a phase 3, double-blind, randomised controlled trial.

BACKGROUND: Novel oral poliovirus vaccine type 2 (nOPV2) has been engineered to improve the genetic stability of Sabin oral poliovirus vaccine (OPV) and reduce the emergence of circulating vaccine-derived polioviruses. This trial aimed to provide key safety and immunogenicity data required for nOPV2 licensure and WHO prequalification. METHODS: This phase 3 trial recruited infants aged 18 to <52 weeks and young children aged 1 to <5 years in The Gambia. Infants randomly assigned to receive one or two doses of one of three lots of nOPV2 or one lot of bivalent OPV (bOPV). Young children were randomised to receive two doses of nOPV2 lot 1 or bOPV. The primary immunogenicity objective was to assess lot-to-lot equivalence of the three nOPV2 lots based on one-dose type 2 poliovirus neutralising antibody seroconversion rates in infants. Equivalence was declared if the 95% CI for the three pairwise rate differences was within the -10% to 10% equivalence margin. Tolerability and safety were assessed based on the rates of solicited adverse events to 7 days, unsolicited adverse events to 28 days, and serious adverse events to 3 months post-dose. Stool poliovirus excretion was examined. The trial was registered as PACTR202010705577776 and is completed. FINDINGS: Between February and October, 2021, 2345 infants and 600 young children were vaccinated. 2272 (96·9%) were eligible for inclusion in the post-dose one per-protocol population. Seroconversion rates ranged from 48·9% to 49·2% across the three lots. The minimum lower bound of the 95% CIs for the pairwise differences in seroconversion rates between lots was -5·8%. The maximum upper bound was 5·4%. Equivalence was therefore shown. Of those seronegative at baseline, 143 (85·6%) of 167 (95% CI 79·4-90·6) infants and 54 (83·1%) of 65 (71·7-91·2) young children seroconverted over the two-dose nOPV2 schedule. The post-two-dose seroprotection rates, including participants who were both seronegative and seropositive at baseline, were 604 (92·9%) of 650 (95% CI 90·7-94·8) in infants and 276 (95·5%) of 289 (92·4-97·6) in young children. No safety concerns were identified. 7 days post-dose one, 78 (41·7%) of 187 (95% CI 34·6-49·1) infants were excreting the type 2 poliovirus. INTERPRETATION: nOPV2 was immunogenic and safe in infants and young children in The Gambia. The data support the licensure and WHO prequalification of nOPV2. FUNDING: Bill & Melinda Gates Foundation.

Diversity of Glossinidae (Diptera) species in The Gambia in relation to vegetation.

Glossina species are known to transmit African Trypanosomiasis, one of the most important infectious diseases for both livestock and humans in sub-Saharan Africa. Therefore, the aim of this study was to characterize trapped Glossina spp. from The Gambia using morphological and molecular techniques in relation to the vegetation cover types. A line transect survey was carried out in all the administrative regions of The Gambia. Tsetse fly trapping was carried out for 14 days during each season using line transect. A total of 220 Glossina spp. specimens (117 F and 103 M) were captured, and DNA was extracted from the legs of 100 randomly selected Glossina spp. Further, DNA samples were tested by a conventional PCR assay. A total of 135/220 (61%; 95% CI: 54.6-67.8%) and 85/220 (39%; 95% CI: 32.2-45.4%) flies were identified as Glossina morsitans submorsitans and Glossina palpalis gambiensis, respectively, with most caught during wet season (53.6%) and more females (53.2%) than males. Results of the morphological identification agreed with those of molecular identification. The type of vegetation cover significantly influenced the caught of tsetse flies. Animals and humans at the various trapping sites are at risk of being bitten by tsetse flies.

Early iron supplementation in exclusively breastfed Gambian infants: a randomized controlled trial.

Objective: To investigate the effect of daily iron supplementation for 14 weeks on the serum iron concentration and other markers of iron status in exclusively breastfed infants in Gambia. Methods: A placebo-controlled, randomized, double-blind trial was performed in rural Gambia between 3 August 2021 and 9 March 2022. Overall, 101 healthy, exclusively breastfed infants aged 6 to 10 weeks were recruited at vaccination clinics and through community health workers. Infants were randomized to receive iron supplementation (7.5 mg/day as ferrous sulfate in sorbitol solution) or placebo for 98 days. Venous blood samples were collected at baseline and on day 99 to assess the serum iron concentration and other markers of iron and haematological status. Findings: At day 99, the serum iron concentration was significantly higher in the iron supplementation group than the placebo group (crude difference in means: 2.5 µmol/L; 95% confidence interval: 0.6 to 4.3) and there were significant improvements in other iron and haematological markers. There were 10 serious adverse events (five in each group), 106 non-serious adverse events (54 with iron supplementation; 52 with placebo) and no deaths. There was no marked difference between the groups in maternally reported episodes of diarrhoea, fever, cough, skin infection, eye infection or nasal discharge. Conclusion: In exclusively breastfed Gambian infants, iron supplementation from 6 weeks of age was associated with a significant improvement in markers of iron status at around 6 months of age. There was no indication of adverse effects on growth or infections.

Tolerability, safety, and immunogenicity of the novel oral polio vaccine type 2 in children aged 6 weeks to 59 months in an outbreak response campaign in The Gambia: an observational cohort study.

BACKGROUND: Novel oral polio vaccine type 2 (nOPV2) has been used to interrupt circulating vaccine-derived poliovirus type 2 outbreaks following its WHO emergency use listing. This study reports data on the safety and immunogenicity of nOPV2 over two rounds of a campaign in The Gambia. METHODS: This observational cohort study collected baseline symptoms (vomiting, diarrhoea, irritability, reduced feeding, and reduced activity) and axillary temperature from children aged 6 weeks to 59 months in The Gambia before a series of two rounds of a nOPV2 campaign that took place on Nov 20-26, 2021, and March 19-22, 2022. Serum and stool samples were collected from a subset of the participants. The same symptoms were re-assessed during the week following each dose of nOPV2. Stool samples were collected on days 7 and 28, and serum was collected on day 28 following each dose. Adverse events, including adverse events of special interest, were documented for 28 days after each campaign round. Serum neutralising antibodies were measured by microneutralisation assay, and stool poliovirus excretion was measured by real-time RT-PCR. FINDINGS: Of the 5635 children eligible for the study, 5504 (97·7%) received at least one dose of nOPV2. There was no increase in axillary temperature or in any of the baseline symptoms following either rounds of the campaigns. There were no adverse events of special interest and no other safety signals of concern. Poliovirus type 2 seroconversion rates were 70% (95% CI 62 to 78; 87 of 124 children) following one dose of nOPV2 and 91% (85 to 95; 113 of 124 children) following two doses. Poliovirus excretion on day 7 was lower after the second round (162 of 459 samples; 35·3%, 95% CI 31·1 to 39·8) than after the first round (292 of 658 samples; 44·4%, 40·6 to 48·2) of the campaign (difference -9·1%; 95% CI -14·8 to -3·3), showing the induction of mucosal immunity. INTERPRETATION: In a campaign in west Africa, nOPV2 was well tolerated and safe. High rates of seroconversion and evidence of mucosal immunity support the licensure and WHO prequalification of this vaccine. FUNDING: Bill & Melinda Gates Foundation.

Asymptomatic Plasmodium falciparum carriage at the end of the dry season is associated with subsequent infection and clinical malaria in Eastern Gambia.

BACKGROUND: Chronic carriage of asymptomatic low-density Plasmodium falciparum parasitaemia in the dry season may support maintenance of acquired immunity that protects against clinical malaria. However, the relationship between chronic low-density infections and subsequent risk of clinical malaria episodes remains unclear. METHODS: In a 2-years study (December 2014 to December 2016) in eastern Gambia, nine cross-sectional surveys using molecular parasite detection were performed in the dry and wet season. During the 2016 malaria transmission season, passive case detection identified episodes of clinical malaria. RESULTS: Among the 5256 samples collected, 444 (8.4%) were positive for P. falciparum. A multivariate model identified village of residence, male sex, age ≥ 5 years old, anaemia, and fever as independent factors associated with P. falciparum parasite carriage. Infections did not cluster over time within the same households or recurred among neighbouring households. Asymptomatic parasite carriage at the end of dry season was associated with a higher risk of infection (Hazard Ratio, HR = 3.0, p < 0.0001) and clinical malaria (HR = 1.561, p = 0.057) during the following transmission season. Age and village of residence were additional predictors of infection and clinical malaria during the transmission season. CONCLUSION: Chronic parasite carriage during the dry season is associated with an increased risk of malaria infection and clinical malaria. It is unclear whether this is due to environmental exposure or to other factors.

Evaluating the sensitivity and specificity of Determine™ HIV-1/2 rapid test using a 0.01M phosphate-buffered saline produced at the Medical Research Council Unit The Gambia for the diagnosis of HIV.

BACKGROUND: Human immunodeficiency virus (HIV) rapid diagnostic tests (RDTs) are widely used. However, buffer stockouts commonly lead to utilising non-approved liquids, resulting in errors. Our aim was to evaluate the diagnostic accuracy of an alternative buffer. METHODS: Paired Determine HIV-1/2 rapid tests with commercial buffer and locally produced 0.01M phosphate-buffered saline (PBS) were performed on consecutive consenting individuals requiring HIV testing. Serum samples were sent for confirmation through the local gold-standard algorithm (Murex HIV Ag/Ab, Hexagon HIV with/without Geenius HIV 1/2). Test accuracy, κ and exact McNemar's test were also carried out. RESULTS: Of 167 participants, 137 had confirmatory testing. The sensitivity of the Determine HIV-1/2 test using PBS compared with the gold standard was 100% (95% confidence interval [CI] 90.5 to 100) with a specificity of 98% (95% CI 92.9 to 99.8). The κ value was 0.94 compared with the gold standard and 0.92 compared with the Determine HIV-1/2 test using the commercial buffer. McNemar's test showed no evidence of differing sensitivities. Due to operational constraints, the study included 37 of the 49 positive cases as determined by the sample size calculation, resulting in an attained power of 80% instead of the intended 90%. CONCLUSIONS: These results suggest that 0.01M PBS is an alternative solution for Determine HIV-1/2 when buffer stockouts occur.

Treat All versus targeted strategies to select HBV-infected people for antiviral therapy in The Gambia, west Africa: a cost-effectiveness analysis.

BACKGROUND: Global elimination of hepatitis B virus (HBV) requires expanded uptake of antiviral therapy, potentially by simplifying testing algorithms, especially in resource-limited countries. We evaluated the effectiveness, cost-effectiveness, and budget impact of three strategies that determine eligibility for anti-HBV treatment, as compared with the WHO 2015 treatment eligibility criteria, in The Gambia. METHODS: We developed a microsimulation model of natural history using data from the Prevention of Liver Fibrosis and Cancer in Africa programme (known as PROLIFICA) in The Gambia, for an HBV-infected cohort of individuals aged 20 years. The algorithms included in the model were a conventional strategy using the European Association for the Study of the Liver (EASL) 2017 criteria, a simplified algorithm using hepatitis B e antigen and alanine aminotransferase (the Treatment Eligibility in Africa for the Hepatitis B Virus [TREAT-B] score), a Treat All approach for all HBV-infected individuals, and the WHO 2015 criteria. Outcomes to measure effectiveness were disability-adjusted life years (DALYs) and years of life saved (YLS), which were used to calculate incremental cost-effectiveness ratios (ICERs) with the WHO 2015 criteria as the base-case scenario. Costs were assessed from a modified social perspective. A budget impact analysis was also done. We tested the robustness of results with a range of sensitiviy analyses including probabilistic sensitivity analysis. FINDINGS: Compared with the WHO criteria, TREAT-B resulted in 4877 DALYs averted and Treat All resulted in 9352 DALYs averted, whereas the EASL criteria led to an excess of 795 DALYs. TREAT-B was cost-saving, whereas the ICER for Treat All (US$2149 per DALY averted) was higher than the cost-effectiveness threshold for The Gambia (0·5 times the country's gross domestic product per capita: $352). These patterns did not change when YLS was the outcome. In a modelled cohort of 5000 adults (aged 20 years) with chronic HBV infection from The Gambia, the 5-year budget impact was $1·14 million for Treat All, $0·66 million for TREAT-B, $1·03 million for the WHO criteria, and $1·16 million for the EASL criteria. Probabilistic sensitivity analysis indicated that among the Treat All, EASL, and TREAT-B algorithms, Treat All would become the most preferred strategy only with a willingness-to-pay threshold exceeding approximately $72 000 per DALY averted or $110 000 per YLS. INTERPRETATION: Although the Treat All strategy might be the most effective, it is unlikely to be cost-effective in The Gambia. A simplified strategy such as TREAT-B might be a cost-saving alternative. FUNDING: UK Research and Innovation (Medical Research Council). TRANSLATION: For the French translation of the abstract see Supplementary Materials section.