Last data update: May 30, 2025. (Total: 49382 publications since 2009)
Records 1-6 (of 6 Records) |
Query Trace: Yamba A[original query] |
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Overcoming practical challenges to pilot Sierra Leone's first school-based distribution of piperonyl butoxide-synergist ITNs: findings from a 2023 assessment in Kono district
Esch K , Yamba F , Opondo K , Sillah-Kanu M , Schnabel D , Owusu P , Sudoi R , Skjefte M , Lahai W , Sheku MG , Jibatteh MK , Ngegbe A , Carlson J , Labor T , Jacob D , Youseff C , Tyler E , Nallo P , Marke D , Poyer S . Malar J 2025 24 (1) 149 BACKGROUND: Continuous distribution of insecticide treated nets (ITNs) through schools is increasingly utilized by National Malaria Programmes across sub-Saharan Africa to maintain coverage between three-year mass distribution campaigns. In March 2023, the Sierra Leone National Malaria Control Programme (NMCP) piloted its first school-based distribution (SBD) in Kono district, reaching 88,605 pupils in 531 schools with piperonyl butoxide-synergist (PBO) ITNs. The pilot was assessed to determine changes in household and population ITN access and use, and to identify areas where future widescale SBD campaigns in Sierra Leone can be improved. METHODS: This was a mixed methods assessment. A cluster, multi-stage sampled household survey was conducted across 950 households, stratified post-hoc by presence (or not) of children eligible for SBD and powered to determine significant differences in ITN access among 'intervention' households (those with at least one eligible child) and 'control' households (those with no eligible children). Key informant interviews (KIIs) were conducted with 26 SBD stakeholders representing government, donors, third party logistics agencies and implementing partners. RESULTS: One- to two-months post SBD, a significantly higher proportion of households in the intervention group owned at least one ITN (93% versus 69%, p < 0.001) and at least one ITN per two people (42% versus 24%, p < 0.001). Population ITN access was significantly higher in the intervention group than the control group (69% versus 46%, p < 0.001). A higher proportion of the population also reported using an ITN the previous night in the intervention group (71%) than the control group (49%) (p < 0.001). KIIs highlighted resolvable challenges, particularly those related to untimely or insufficient funding, which led to subsequent issues for coordination, storage, transportation, quantification, distribution, training, microplanning and supervision. CONCLUSION: Sierra Leone's SBD pilot significantly improved key ITN ownership, use and access indicators at the household and population levels in Kono district one- to two-months post-SBD. However, intervention population ITN use, and access were still below the NMCP's 80% target. Gaps should be addressed for SBD scale-up. Research on costing, sustained levels of ITN use and access, and the effect of SBD ITNs on malaria parasitaemia may be considered by the NMCP. |
Characterization of insecticide resistance mechanisms in the Anopheles gambiae population of Sierra Leone
Opondo KO , Alyko E , Smith S , Levine R , Donnelly J , Hughes T , Schnabel D , Jose R , Jalloh A , Lolleh U , Conteh S , Iyikirenga L , Jacob D , Mokuena M , Yamba F , Yihdego Y . Malar J 2025 24 (1) 80 ![]() ![]() BACKGROUND: Information on the status of insecticide resistance in malaria vectors is critical for implementing effective malaria vector control. The Sierra Leone National Malaria Control Programme, in collaboration with the PMI VectorLink project, assessed the resistance status to insecticides commonly used in public health, and associated resistance mechanisms in Anopheles gambiae, the main vector of malaria in Sierra Leone. METHODS: The susceptibility of An. gambiae against pyrethroids with and without piperonyl butoxide (PBO), chlorfenapyr, clothianidin, bendiocarb and pirimiphos-methyl was evaluated in four districts of Sierra Leone in 2018 and 2019 using WHO and CDC bottle bioassay protocols. A subset of samples that were exposed to the insecticides were screened for molecular markers of insecticide resistance, knock-down resistance (kdr) L1014F, 1014S and N1575Y, and (ace-1-G119S). RESULTS: Anopheles gambiae from all sites were resistant to the diagnostic doses of three pyrethroids: deltamethrin, permethrin and alpha-cypermethrin. Intensity of resistance to all three pyrethroids was high, with less than 95% mortality at 10X concentration. However, pre-exposure of An. gambiae to PBO increased overall mortality by 41.6%, 50.0% and 44.0% for deltamethrin, permethrin and alpha-cypermethrin, respectively. The vector was susceptible to chlorfenapyr, clothianidin and pirimiphos-methyl, while bendiocarb showed possible resistance. The frequency of kdr alleles was 98.2% for L1014F, 2.1% for 1014S and 8.9% for N1575Y, while the frequency of the Ace-1 G119S allele was 13.6%. Significant deviation from the Hardy-Weinberg equilibrium and deficiency of heterozygotes was detected only at the G119S locus of An. gambiae (p < 0.0001). Of the 191 An. gambiae sensu lato that were molecularly identified to the species level, 81.7% were An. gambiae sensu stricto (95% CI 75.3-86.7), followed by Anopheles coluzzii (17.8%, 95% CI (12.8-24.1) with one hybrid of An. gambiae/An. coluzzii 0.5%, 95% CI (0.03-3.3). CONCLUSION: Malaria vectors were highly resistant to pyrethroids but exposure to PBO partially restored susceptibility in An. gambiae s.l. in Sierra Leone. Malaria vectors were susceptible to chlorfenapyr, clothianidin and pirimiphos-methyl with possible resistance to bendiocarb. These data informed the selection and distribution of ITN PBO in Sierra Leone's mass campaigns in 2020 and selection of clothianidin for indoor residual spraying in 2021. |
High prevalence of pre-treatment HIV drug resistance in Papua New Guinea: findings from the first nationally representative pre-treatment HIV drug resistance study.
Gare J , Toto B , Pokeya P , Le LV , Dala N , Lote N , John B , Yamba A , Soli K , DeVos J , Paulin H , Wagar N , Zheng DP , Nishijima T , Boas P , Kelly-Hanku A , Gurung A . BMC Infect Dis 2022 22 (1) 266 ![]() ![]() BACKGROUND: Determining the prevalence of pre-treatment HIV drug resistance (PDR) is important to assess the effectiveness of first-line therapies. To determine PDR prevalence in Papua New Guinea (PNG), we conducted a nationally representative survey. METHODS: We used a two-stage cluster sampling method to recruit HIV treatment initiators with and without prior exposure to antiretroviral therapies (ART) in selected clinics. Dried blood spots were collected and tested for PDR. RESULTS: A total of 315 sequences were available for analysis. The overall PDR prevalence rate was 18.4% (95% CI 13.8-24.3%). The prevalence of PDR to non-nucleoside analog reverse-transcriptase inhibitors (NNRTIs) was 17.8% (95% CI 13.6-23.0%) and of PDR to nucleoside reverse transcriptase inhibitors (NRTIs) was 6.3% (95% CI 1.6-17.1%). The PDR prevalence rate among people reinitiating ART was 42.4% (95% CI 29.1-56.4%). CONCLUSIONS: PNG has a high PDR prevalence rate, especially to NNRTI-based first-line therapies. Our findings suggest that removing NNRTIs as part of first-line treatment is warranted and will lead to improving viral suppression rates in PNG. |
Persistence of Ebola virus in semen among Ebola virus disease survivors in Sierra Leone: A cohort study of frequency, duration, and risk factors.
Thorson AE , Deen GF , Bernstein KT , Liu WJ , Yamba F , Habib N , Sesay FR , Gaillard P , Massaquoi TA , McDonald SLR , Zhang Y , Durski KN , Singaravelu S , Ervin E , Liu H , Coursier A , Marrinan JE , Ariyarajah A , Carino M , Formenty P , Ströher U , Lamunu M , Wu G , Sahr F , Xu W , Knust B , Broutet N . PLoS Med 2021 18 (2) e1003273 ![]() ![]() BACKGROUND: Sexual transmission chains of Ebola virus (EBOV) have been verified and linked to EBOV RNA persistence in semen, post-recovery. The rate of semen persistence over time, including the average duration of persistence among Ebola virus disease (EVD) survivors, is not well known. This cohort study aimed to analyze population estimates of EBOV RNA persistence rates in semen over time, and associated risk factors in a population of survivors from Sierra Leone. METHODS AND FINDINGS: In this cohort study from May 2015 to April 2017 in Sierra Leone, recruitment was conducted in 2 phases; the first enrolled 100 male participants from the Western Area District in the capital of Freetown, and the second enrolled 120 men from the Western Area District and from Lungi, Port Loko District. Mean age of participants was 31 years. The men provided semen for testing, analyzed by quantitative reverse transcription PCR (qRT-PCR) for the presence of EBOV RNA. Follow-up occurred every 2 weeks until the endpoint, defined as 2 consecutive negative qRT-PCR results of semen specimen testing for EBOV RNA. Participants were matched with the Sierra Leone EVD case database to retrieve cycle threshold (Ct) values from the qRT-PCR analysis done in blood during acute disease. A purposive sampling strategy was used, and the included sample composition was compared to the national EVD survivor database to understand deviations from the general male survivor population. At 180 days (6 months) after Ebola treatment unit (ETU) discharge, the EBOV RNA semen positive rate was 75.4% (95% CI 66.9%-82.0%). The median persistence duration was 204 days, with 50% of men having cleared their semen of EBOV RNA after this time. At 270 days, persistence was 26.8% (95% CI 20.0%-34.2%), and at 360 days, 6.0% (95% CI 3.1%-10.2%). Longer persistence was significantly associated with severe acute disease, with probability of persistence in this population at 1 year at 10.1% (95% CI 4.6%-19.8%) compared to the probability approaching 0% for those with mild acute disease. Age showed a dose-response pattern, where the youngest men (≤25 years) were 3.17 (95% CI 1.60, 6.29) times more likely to be EBOV RNA negative in semen, and men aged 26-35 years were 1.85 (95% CI 1.04, 3.28) times more likely to be negative, than men aged >35 years. Among participants with both severe acute EVD and a higher age (>35 years), persistence remained above 20% (95% CI 6.0%-50.6%) at 1 year. Uptake of safe sex recommendations 3 months after ETU discharge was low among a third of survivors. The sample was largely representative of male survivors in Sierra Leone. A limitation of this study is the lack of knowledge about infectiousness. CONCLUSIONS: In this study we observed that EBOV RNA persistence in semen was a frequent phenomenon, with high population rates over time. This finding will inform forthcoming updated recommendations on risk reduction strategies relating to sexual transmission of EBOV. Our findings support implementation of a semen testing program as part of epidemic preparedness and response. Further, the results will enable planning of the magnitude of testing and targeted counseling needs over time. |
Lessons from the first 6 years of an intervention-based field epidemiology training programme in Papua New Guinea, 2013-2018
Ropa B , Flint J , O'Reilly M , Pavlin BI , Dagina R , Peni B , Bauri M , Pukienei A , Merritt T , Terrell-Perica S , Yamba A , Prybylski D , Collins J , Durrheim DN , Henderson A , Bieb S . BMJ Glob Health 2019 4 (6) e001969 Papua New Guinea (PNG) faces a critical shortage of human resources to address pressing public health challenges arising from an increasing burden of communicable and non-communicable diseases. PNG is an independent State in the Pacific and home to 8.2 million people. Resource and infrastructure constraints due to the country's challenging geography have made it difficult and expensive to deliver health services and implement health programmes. The National Department of Health and its partners developed a field epidemiology training programme of Papua New Guinea (FETPNG) to strengthen the country's public health workforce. The training programme covers field epidemiology competencies and includes the design, implementation and evaluation of evidence-based interventions by Fellows. From 2013 to 2018, FETPNG graduated 81 field epidemiologists. Most FETPNG graduates (84%) were from provincial or district health departments or organisations. Many of their intervention projects resulted in successful public health outcomes with tangible local impacts. Health challenges addressed included reducing the burden of multi-drug resistant-tuberculosis (TB), increasing immunisation coverage, screening and treating HIV/TB patients, and improving reproductive health outcomes. FETPNG Fellows and graduates have also evaluated disease surveillance systems and investigated disease outbreaks. Early and unwavering national ownership of FETPNG created a sustainable programme fitting the needs of this low-resource country. A focus on designing and implementing effective public health interventions not only provides useful skills to Fellows but also contributes to real-time, tangible and meaningful improvements in the health of the population. The graduates of FETPNG now provide a critical mass of public health practitioners across the country. Their skills in responding to outbreaks and public health emergencies, in collecting, analysing and interpreting data, and in designing, implementing and evaluating public health interventions continues to advance public health in PNG. |
National health information systems for achieving the Sustainable Development Goals
Suthar AB , Khalifa A , Joos O , Manders EJ , Abdul-Quader A , Amoyaw F , Aoua C , Aynalem G , Barradas D , Bello G , Bonilla L , Cheyip M , Dalhatu IT , De Klerk M , Dee J , Hedje J , Jahun I , Jantaramanee S , Kamocha S , Lerebours L , Lobognon LR , Lote N , Lubala L , Magazani A , Mdodo R , Mgomella GS , Monique LA , Mudenda M , Mushi J , Mutenda N , Nicoue A , Ngalamulume RG , Ndjakani Y , Nguyen TA , Nzelu CE , Ofosu AA , Pinini Z , Ramirez E , Sebastian V , Simanovong B , Son HT , Son VH , Swaminathan M , Sivile S , Teeraratkul A , Temu P , West C , Xaymounvong D , Yamba A , Yoka D , Zhu H , Ransom RL , Nichols E , Murrill CS , Rosen D , Hladik W . BMJ Open 2019 9 (5) e027689 OBJECTIVES: Achieving the Sustainable Development Goals will require data-driven public health action. There are limited publications on national health information systems that continuously generate health data. Given the need to develop these systems, we summarised their current status in low-income and middle-income countries. SETTING: The survey team jointly developed a questionnaire covering policy, planning, legislation and organisation of case reporting, patient monitoring and civil registration and vital statistics (CRVS) systems. From January until May 2017, we administered the questionnaire to key informants in 51 Centers for Disease Control country offices. Countries were aggregated for descriptive analyses in Microsoft Excel. RESULTS: Key informants in 15 countries responded to the questionnaire. Several key informants did not answer all questions, leading to different denominators across questions. The Ministry of Health coordinated case reporting, patient monitoring and CRVS systems in 93% (14/15), 93% (13/14) and 53% (8/15) of responding countries, respectively. Domestic financing supported case reporting, patient monitoring and CRVS systems in 86% (12/14), 75% (9/12) and 92% (11/12) of responding countries, respectively. The most common uses for system-generated data were to guide programme response in 100% (15/15) of countries for case reporting, to calculate service coverage in 92% (12/13) of countries for patient monitoring and to estimate the national burden of disease in 83% (10/12) of countries for CRVS. Systems with an electronic component were being used for case reporting, patient monitoring, birth registration and death registration in 87% (13/15), 92% (11/12), 77% (10/13) and 64% (7/11) of responding countries, respectively. CONCLUSIONS: Most responding countries have a solid foundation for policy, planning, legislation and organisation of health information systems. Further evaluation is needed to assess the quality of data generated from systems. Periodic evaluations may be useful in monitoring progress in strengthening and harmonising these systems over time. |
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