Last data update: Sep 16, 2024. (Total: 47680 publications since 2009)
Records 1-30 (of 54 Records) |
Query Trace: Ndiaye S [original query] |
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Two decades of molecular surveillance in Senegal reveal rapid changes in known drug resistance mutations over time
Ndiaye YD , Wong W , Thwing J , Schaffner SF , Brenneman KV , Tine A , Diallo MA , Deme AB , Sy M , Bei AK , Thiaw AB , Daniels R , Ndiaye T , Gaye A , Ndiaye IM , Toure M , Gadiaga N , Sene A , Sow D , Garba MN , Yade MS , Dieye B , Diongue K , Zoumarou D , Ndiaye A , Gomis JF , Fall FB , Ndiop M , Diallo I , Sene D , Macinnis B , Seck MC , Ndiaye M , Ngom B , Diedhiou Y , Mbaye AM , Ndiaye L , Sy N , Badiane AS , Hartl DL , Wirth DF , Volkman SK , Ndiaye D . Malar J 2024 23 (1) 205 BACKGROUND: Drug resistance in Plasmodium falciparum is a major threat to malaria control efforts. Pathogen genomic surveillance could be invaluable for monitoring current and emerging parasite drug resistance. METHODS: Data from two decades (2000-2020) of continuous molecular surveillance of P. falciparum parasites from Senegal were retrospectively examined to assess historical changes in malaria drug resistance mutations. Several known drug resistance markers and their surrounding haplotypes were profiled using a combination of single nucleotide polymorphism (SNP) molecular surveillance and whole genome sequence based population genomics. RESULTS: This dataset was used to track temporal changes in drug resistance markers whose timing correspond to historically significant events such as the withdrawal of chloroquine (CQ) and the introduction of sulfadoxine-pyrimethamine (SP) in 2003. Changes in the mutation frequency at Pfcrt K76T and Pfdhps A437G coinciding with the 2014 introduction of seasonal malaria chemoprevention (SMC) in Senegal were observed. In 2014, the frequency of Pfcrt K76T increased while the frequency of Pfdhps A437G declined. Haplotype-based analyses of Pfcrt K76T showed that this rapid increase was due to a recent selective sweep that started after 2014. DISCUSSION (CONCLUSION): The rapid increase in Pfcrt K76T is troubling and could be a sign of emerging amodiaquine (AQ) resistance in Senegal. Emerging AQ resistance may threaten the future clinical efficacy of artesunate-amodiaquine (ASAQ) and AQ-dependent SMC chemoprevention. These results highlight the potential of molecular surveillance for detecting rapid changes in parasite populations and stress the need to monitor the effectiveness of AQ as a partner drug for artemisinin-based combination therapy (ACT) and for chemoprevention. |
Development of a maturity assessment tool to evaluate and strengthen National Immunization Technical Advisory Groups (NITAGs)
Dryer E , Shefer A , Desai S , Rodewald L , Bastías M , El Omeiri N , Ndiaye S , Cook K , Henaff L , Kennedy E . Vaccine 2024 As dozens of new National Immunization Technical Advisory Groups (NITAGs) were established worldwide in the past decade, and as existing NITAGs continued to play an important role in vaccine policy, global NITAG partners recognized a need for a standardized assessment tool to evaluate and strengthen their functions. This article describes the development of the NITAG Maturity Assessment Tool (NMAT), a stepwise evaluation tool that assesses NITAGs on seven key indicators of structure and process. A draft tool was developed through an iterative, consensus-based process with an expert working group before it was piloted with an economically and geographically diverse convenience sample of NITAGs. The final NMAT is a flexible tool that can be used by in-country or external evaluators to understand NITAG maturity, identify priorities for optimization, and measure the impact of strengthening efforts. |
Distribution and dynamics of Anopheles gambiae s.l. larval habitats in three Senegalese cities with high urban malaria incidence
Ndiaye F , Diop A , Chabi J , Sturm-Ramirez K , Senghor M , Diouf EH , Samb B , Diedhiou SM , Thiaw O , Zohdy S , Dotson E , Sene D , Diouf MB , Koscelnik V , Gerberg L , Bangoura A , Clark T , Faye O , Dia I , Konate L , Niang EHA . PLoS One 2024 19 (5) e0303473 Urban malaria has become a challenge for most African countries due to urbanization, with increasing population sizes, overcrowding, and movement into cities from rural localities. The rapid expansion of cities with inappropriate water drainage systems, abundance of water storage habitats, coupled with recurrent flooding represents a concern for water-associated vector borne diseases, including malaria. This situation could threaten progress made towards malaria elimination in sub-Saharan countries, including Senegal, where urban malaria has presented as a threat to national elimination gains. To assess drivers of urban malaria in Senegal, a 5-month study was carried out from August to December 2019 in three major urban areas and hotspots for malaria incidence (Diourbel, Touba, and Kaolack) including the rainy season (August-October) and partly dry season (November-December). The aim was to characterize malaria vector larval habitats, vector dynamics across both seasons, and to identify the primary eco- environmental entomological factors contributing to observed urban malaria transmission. A total of 145 Anopheles larval habitats were found, mapped, and monitored monthly. This included 32 in Diourbel, 83 in Touba, and 30 in Kaolack. The number of larval habitats fluctuated seasonally, with a decrease during the dry season. In Diourbel, 22 of the 32 monitored larval habitats (68.75%) were dried out by December and considered temporary, while the remaining 10 (31.25%) were classified as permanent. In the city of Touba 28 (33.73%) were temporary habitats, and of those 57%, 71% and 100% dried up respectively by October, November, and December. However, 55 (66.27%) habitats were permanent water storage basins which persisted throughout the study. In Kaolack, 12 (40%) permanent and 18 (60%) temporary Anopheles larval habitats were found and monitored during the study. Three malaria vectors (An. arabiensis, An. pharoensis and An. funestus s.l.) were found across the surveyed larval habitats, and An. arabiensis was found in all three cities and was the only species found in the city of Diourbel, while An. arabiensis, An. pharoensis, and An. funestus s.l. were detected in the cities of Touba and Kaolack. The spatiotemporal observations of immature malaria vectors in Senegal provide evidence of permanent productive malaria vector larval habitats year-round in three major urban centers in Senegal, which may be driving high urban malaria incidence. This study aimed to assess the presence and type of anopheline larvae habitats in urban areas. The preliminary data will better inform subsequent detailed additional studies and seasonally appropriate, cost-effective, and sustainable larval source management (LSM) strategies by the National Malaria Control Programme (NMCP). |
Evaluating the performance of Plasmodium falciparum genetic metrics for inferring National Malaria Control Programme reported incidence in Senegal
Wong W , Schaffner SF , Thwing J , Seck MC , Gomis J , Diedhiou Y , Sy N , Ndiop M , Ba F , Diallo I , Sene D , Diallo MA , Ndiaye YD , Sy M , Sene A , Sow D , Dieye B , Tine A , Ribado J , Suresh J , Lee A , Battle KE , Proctor JL , Bever CA , MacInnis B , Ndiaye D , Hartl DL , Wirth DF , Volkman SK . Malar J 2024 23 (1) 68 BACKGROUND: Genetic surveillance of the Plasmodium falciparum parasite shows great promise for helping National Malaria Control Programmes (NMCPs) assess parasite transmission. Genetic metrics such as the frequency of polygenomic (multiple strain) infections, genetic clones, and the complexity of infection (COI, number of strains per infection) are correlated with transmission intensity. However, despite these correlations, it is unclear whether genetic metrics alone are sufficient to estimate clinical incidence. METHODS: This study examined parasites from 3147 clinical infections sampled between the years 2012-2020 through passive case detection (PCD) across 16 clinic sites spread throughout Senegal. Samples were genotyped with a 24 single nucleotide polymorphism (SNP) molecular barcode that detects parasite strains, distinguishes polygenomic (multiple strain) from monogenomic (single strain) infections, and identifies clonal infections. To determine whether genetic signals can predict incidence, a series of Poisson generalized linear mixed-effects models were constructed to predict the incidence level at each clinical site from a set of genetic metrics designed to measure parasite clonality, superinfection, and co-transmission rates. RESULTS: Model-predicted incidence was compared with the reported standard incidence data determined by the NMCP for each clinic and found that parasite genetic metrics generally correlated with reported incidence, with departures from expected values at very low annual incidence (< 10/1000/annual [‰]). CONCLUSIONS: When transmission is greater than 10 cases per 1000 annual parasite incidence (annual incidence > 10‰), parasite genetics can be used to accurately infer incidence and is consistent with superinfection-based hypotheses of malaria transmission. When transmission was < 10‰, many of the correlations between parasite genetics and incidence were reversed, which may reflect the disproportionate impact of importation and focal transmission on parasite genetics when local transmission levels are low. |
Supporting National Immunization Technical Advisory Groups (NITAGs) in development of evidence-based vaccine recommendations and NITAG assessments - New tools and approaches
Hadler SC , Shefer AM , Cavallaro KF , Ebama M , Tencza C , Kennedy ED , Ndiaye S , Shah A , Torre L , Bresee JS . Vaccine 2024 Increasing opportunities for prevention of infectious diseases by new, effective vaccines and the expansion of global immunization programs across the life course highlight the importance and value of evidence-informed decision-making (EIDM) by National Immunization Technical Advisory Groups (NITAGs). The U.S. Centers for Disease Control and Prevention (CDC) and Task Force for Global Health (TFGH) have developed and made available new tools to support NITAGs in EIDM. These include a toolkit for conducting facilitated training of NITAGs, Secretariats, or work groups on the use of the Evidence to Recommendations (EtR) approach to advise Ministries of Health (MoH) on specific vaccine policies, and an eLearning module on the EtR approach for NITAG members, Secretariat and others. The CDC and TFGH have also supported final development and implementation of the NITAG Maturity Assessment Tool (NMAT) for assessing maturity of NITAG capabilities in seven functional domains. The EtR toolkit and eLearning have been widely promoted in collaboration with the World Health Organization (WHO) Headquarters and Regional Offices through workshops engaging over 30 countries to date, and the NMAT assessment tool used in most countries in 3 WHO regions (Americas, Eastern Mediterranean, African). Important lessons have been learned regarding planning and conducting trainings for multiple countries and additional ways to support countries in applying the EtR approach to complete vaccine recommendations. Priorities for future work include the need to evaluate the impact of EtR training and NMAT assessments, working with partners to expand and adapt these tools for wider use, synergizing with other approaches for NITAG strengthening, and developing the best approaches to empower NITAGs to use the EtR approach. |
Seroprevalence to schistosoma soluble egg antigen among nomadic pastoralists residing in Northern Senegal
Seck MC , Badiane AS , Thwing J , Ndiaye M , Diongue K , Ndiaye IM , Diallo MA , Sy M , Gomis JF , Ndiaye T , Gaye A , Lee YM , Secor WE , Ndiaye D , Rogier E . J Parasitol 2023 109 (6) 580-587 Urinary and intestinal schistosomiasis are endemic in Senegal, with prevalence heterogeneous throughout the country. Because of their way of life, nomadic pastoralists are not typically included in epidemiological surveys, and data on the prevalence of schistosomiasis in Senegalese nomadic populations are largely non-existent. The purpose of this study was to determine the seroprevalence of schistosomiasis in Senegalese nomadic pastoralists. A modified snowball sampling survey was conducted among 1,467 nomadic pastoralists aged 6 mo and older in 5 districts in northern Senegal. Dried blood spots from participants of all ages and data regarding demographics were collected to assess IgG antibody responses against Schistosoma mansoni soluble egg antigen (SEA) using a bead-based multiplex assay. Out of 1,467 study subjects, 1,464 (99.8%) provided IgG serological data that cleared quality assurance. Of the participants with appropriate data, 56.6% were male, the median age was 22 yr, and 31.6% were under 15 yr of age. The overall anti-SEA IgG seroprevalence was 19.1% (95% confidence interval [CI]: 17.1-21.1%) with the highest estimates observed in Dagana (35.9%) and the lowest observed in Podor nomadic groups (3.4%). Antibody responses increased significantly with age except for the oldest age groups (>40 yr of age), which saw lower levels of antibody response compared to younger adults. When controlling for age and location by multivariate regression, the male sex was associated with a 2-fold greater odds of anti-SEA IgG seropositivity (aPOR: 2.0; 95% CI: 1.5-2.7). Serosurveys for anti-SEA IgG among nomadic peoples in northern Senegal found a substantial percentage of individuals with evidence for current or previous Schistosoma spp. infection with the highest levels of exposure in the district adjacent to the Diama dam along the Senegal River. With IgG prevalence increased by age except in the older adults, and the male sex significantly associated with seropositivity, these data point toward sex-associated behavioral practices and human environmental modification as risk factors for Schistosoma exposure. |
Evaluating the performance of Plasmodium falciparum genetics for inferring National Malaria Control Program reported incidence in Senegal
Wong W , Schaffner SF , Thwing J , Seck MC , Gomis J , Diedhiou Y , Sy N , Ndiop M , Ba F , Diallo I , Sene D , Diallo MA , Ndiaye YD , Sy M , Sene A , Sow D , Dieye B , Tine A , Ribado J , Suresh J , Lee A , Battle KE , Proctor JL , Bever CA , MacInnis B , Ndiaye D , Hartl DL , Wirth DF , Volkman SK . Res Sq 2023 Genetic surveillance of the Plasmodium falciparum parasite shows great promise for helping National Malaria Control Programs (NMCPs) assess parasite transmission. Genetic metrics such as the frequency of polygenomic (multiple strain) infections, genetic clones, and the complexity of infection (COI, number of strains per infection) are correlated with transmission intensity. However, despite these correlations, it is unclear whether genetic metrics alone are sufficient to estimate clinical incidence. Here, we examined parasites from 3,147 clinical infections sampled between the years 2012-2020 through passive case detection (PCD) across 16 clinic sites spread throughout Senegal. Samples were genotyped with a 24 single nucleotide polymorphism (SNP) molecular barcode that detects parasite strains, distinguishes polygenomic (multiple strain) from monogenomic (single strain) infections, and identifies clonal infections. To determine whether genetic signals can predict incidence, we constructed a series of Poisson generalized linear mixed-effects models to predict the incidence level at each clinical site from a set of genetic metrics designed to measure parasite clonality, superinfection, and co-transmission rates. We compared the model-predicted incidence with the reported standard incidence data determined by the NMCP for each clinic and found that parasite genetic metrics generally correlated with reported incidence, with departures from expected values at very low annual incidence (<10/1000/annual [‰]). When transmission is greater than 10 cases per 1000 annual parasite incidence (annual incidence >10 ‰), parasite genetics can be used to accurately infer incidence and is consistent with superinfection-based hypotheses of malaria transmission. When transmission was <10 ‰, we found that many of the correlations between parasite genetics and incidence were reversed, which we hypothesize reflects the disproportionate impact of importation and focal transmission on parasite genetics when local transmission levels are low. |
Malaria surveillance reveals parasite relatedness, signatures of selection, and correlates of transmission across Senegal
Schaffner SF , Badiane A , Khorgade A , Ndiop M , Gomis J , Wong W , Ndiaye YD , Diedhiou Y , Thwing J , Seck MC , Early A , Sy M , Deme A , Diallo MA , Sy N , Sene A , Ndiaye T , Sow D , Dieye B , Ndiaye IM , Gaye A , Ndiaye A , Battle KE , Proctor JL , Bever C , Fall FB , Diallo I , Gaye S , Sene D , Hartl DL , Wirth DF , MacInnis B , Ndiaye D , Volkman SK . Nat Commun 2023 14 (1) 7268 We here analyze data from the first year of an ongoing nationwide program of genetic surveillance of Plasmodium falciparum parasites in Senegal. The analysis is based on 1097 samples collected at health facilities during passive malaria case detection in 2019; it provides a baseline for analyzing parasite genetic metrics as they vary over time and geographic space. The study's goal was to identify genetic metrics that were informative about transmission intensity and other aspects of transmission dynamics, focusing on measures of genetic relatedness between parasites. We found the best genetic proxy for local malaria incidence to be the proportion of polygenomic infections (those with multiple genetically distinct parasites), although this relationship broke down at low incidence. The proportion of related parasites was less correlated with incidence while local genetic diversity was uninformative. The type of relatedness could discriminate local transmission patterns: two nearby areas had similarly high fractions of relatives, but one was dominated by clones and the other by outcrossed relatives. Throughout Senegal, 58% of related parasites belonged to a single network of relatives, within which parasites were enriched for shared haplotypes at known and suspected drug resistance loci and at one novel locus, reflective of ongoing selection pressure. |
Urban malaria vector bionomics and human sleeping behavior in three cities in Senegal
Diop A , Ndiaye F , Sturm-Ramirez K , Konate L , Senghor M , Diouf EH , Dia AK , Diedhiou S , Samb B , Sene D , Zohdy S , Dotson E , Diouf MB , Koscelnik V , Gerberg L , Bangoura A , Faye O , Clark T , Niang EHA , Chabi J . Parasit Vectors 2023 16 (1) 331 BACKGROUND: Malaria is endemic in Senegal, with seasonal transmission, and the entire population is at risk. In recent years, high malaria incidence has been reported in urban and peri-urban areas of Senegal. An urban landscape analysis was conducted in three cities to identify the malaria transmission indicators and human behavior that may be driving the increasing malaria incidence occurring in urban environments. Specifically, mosquito vector bionomics and human sleeping behaviors including outdoor sleeping habits were assessed to guide the optimal deployment of targeted vector control interventions. METHODS: Longitudinal entomological monitoring using human landing catches and pyrethrum spray catches was conducted from May to December 2019 in Diourbel, Kaolack, and Touba, the most populous cities in Senegal after the capital Dakar. Additionally, a household survey was conducted in randomly selected houses and residential Koranic schools in the same cities to assess house structures, sleeping spaces, sleeping behavior, and population knowledge about malaria and vector control measures. RESULTS: Of the 8240 Anopheles mosquitoes collected from all the surveyed sites, 99.4% (8,191) were An. gambiae s.l., and predominantly An. arabiensis (99%). A higher number of An. gambiae s.l. were collected in Kaolack (77.7%, n = 6496) than in Diourbel and Touba. The overall mean human biting rate was 14.2 bites per person per night (b/p/n) and was higher outdoors (15.9 b/p/n) than indoors (12.5 b/p/n). The overall mean entomological inoculation rates ranged from 3.7 infectious bites per person per year (ib/p/y) in Diourbel to 40.2 ib/p/y in Kaolack. Low anthropophilic rates were recorded at all sites (average 35.7%). Of the 1202 households surveyed, about 24.3% of household members slept outdoors, except during the short rainy season between July and October, despite understanding how malaria is transmitted and the vector control measures used to prevent it. CONCLUSION: Anopheles arabiensis was the primary malaria vector in the three surveyed cities. The species showed an outdoor biting tendency, which represents a risk for the large proportion of the population sleeping outdoors. As all current vector control measures implemented in the country target endophilic vectors, these data highlight potential gaps in population protection and call for complementary tools and approaches targeting outdoor biting malaria vectors. |
Defining operational research priorities to improve malaria control and elimination in sub-Saharan Africa: Results from a country-driven research prioritization setting process
Tine R , Herrera S , Badji MA , Daniels K , Ndiaye P , Smith Gueye C , Tairou F , Slutsker L , Hwang J , Ansah E , Littrell M . Malar J 2023 22 (1) 219 BACKGROUND: In order to reignite gains and accelerate progress toward improved malaria control and elimination, policy, strategy, and operational decisions should be derived from high-quality evidence. The U.S. President's Malaria Initiative (PMI) Insights project together with the Université Cheikh Anta Diop of Dakar, Senegal, conducted a broad stakeholder consultation process to identify pressing evidence gaps in malaria control and elimination across sub-Saharan Africa (SSA), and developed a priority list of country-driven malaria operational research (OR) and programme evaluation (PE) topics to address these gaps. METHODS: Five key stakeholder groups were engaged in the process: national malaria programmes (NMPs), research institutions in SSA, World Health Organization (WHO) representatives in SSA, international funding agencies, and global technical partners who support malaria programme implementation and research. Stakeholders were engaged through individual or small group interviews and an online survey, and asked about key operational challenges faced by NMPs, pressing evidence gaps in current strategy and implementation guidance, and priority OR and PE questions to address the challenges and gaps. RESULTS: Altogether, 47 interviews were conducted with 82 individuals, and through the online survey, input was provided by 46 global technical partners. A total of 33 emergent OR and PE topics were identified through the consultation process and were subsequently evaluated and prioritized by an external evaluation committee of experts from NMPs, research institutions, and the WHO. The resulting prioritized OR and PE topics predominantly focused on generating evidence needed to close gaps in intervention coverage, address persistent challenges faced by NMPs in the implementation of core strategic interventions, and inform the effective deployment of new tools. CONCLUSION: The prioritized research list is intended to serve as a key resource for informing OR and PE investments, thereby ensuring future investments focus on generating the evidence needed to strengthen national strategies and programme implementation and facilitating a more coordinated and impactful approach to malaria operational research. |
Two decades of molecular surveillance in Senegal reveal changes in known drug resistance mutations associated with historical drug use and seasonal malaria chemoprevention (preprint)
Ndiaye YD , Wong W , Thwing J , Schaffner SS , Tine A , Diallo MA , Deme A , Sy M , Bei AK , Thiaw AB , Daniels R , Ndiaye T , Gaye A , Ndiaye IM , Toure M , Gadiaga N , Sene A , Sow D , Garba MN , Yade MS , Dieye B , Diongue K , Zoumarou D , Ndiaye A , Gomis J , Fall FB , Ndiop M , Diallo I , Sene D , Macinnis B , Seck MC , Ndiaye M , Badiane AS , Hartl DL , Volkman SK , Wirth DF , Ndiaye D . medRxiv 2023 26 Drug resistance in Plasmodium falciparum is a major threat to malaria control efforts. We analyzed data from two decades (2000-2020) of continuous molecular surveillance of P. falciparum parasite strains in Senegal to determine how historical changes in drug administration policy may have affected parasite evolution. We profiled several known drug resistance markers and their surrounding haplotypes using a combination of single nucleotide polymorphism (SNP) molecular surveillance and whole-genome sequence (WGS) based population genomics. We observed rapid changes in drug resistance markers associated with the withdrawal of chloroquine and introduction of sulfadoxine-pyrimethamine in 2003. We also observed a rapid increase in Pfcrt K76T and decline in Pfdhps A437G starting in 2014, which we hypothesize may reflect changes in resistance or fitness caused by seasonal malaria chemoprevention (SMC). Parasite populations evolve rapidly in response to drug use, and SMC preventive efficacy should be closely monitored. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. |
Malaria surveillance reveals parasite relatedness, signatures of selection, and correlates of transmission across Senegal (preprint)
Schaffner SF , Badiane A , Khorgade A , Ndiop M , Gomis J , Wong W , Ndiaye YD , Diedhiou Y , Thwing J , Seck MC , Early A , Sy M , Deme A , Diallo MA , Sy N , Sene A , Ndiaye T , Sow D , Dieye B , Ndiaye IM , Gaye A , Ndiaye A , Battle KE , Proctor JL , Bever C , Fall FB , Diallo I , Gaye S , Sene D , Hartl DL , Wirth DF , MacInnis B , Ndiaye D , Volkman SK . medRxiv 2023 17 Parasite genetic surveillance has the potential to play an important role in malaria control. We describe here an analysis of data from the first year of an ongoing, nationwide program of genetic surveillance of Plasmodium falciparum parasites in Senegal, intended to provide actionable information for malaria control efforts. Looking for a good proxy for local malaria incidence, we found that the best predictor was the proportion of polygenomic infections (those with multiple genetically distinct parasites), although that relationship broke down at very low incidence. The proportion of closely related parasites in a site was more weakly correlated with incidence while the local genetic diversity was uninformative. Study of related parasites indicated their potential for discriminating local transmission patterns: two nearby study areas had similarly high fractions of relatives, but one area was dominated by clones and the other by outcrossed relatives. Throughout the country, most related parasites proved to belong to a single network of relatives, within which parasites were enriched for shared haplotypes at known and suspected drug resistance loci as well as at one novel locus, reflective of ongoing selection pressure. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. |
Evaluation of the Performance of the Routine Epidemiological Surveillance System in the Health District of Tambacounda (Senegal) in 2020 (preprint)
Gadiaga T , Ba MF , Sagna S , Cisse B , Diallo A , Ndiaye S , Diop B , Ndiaye M , Ndoye B , Ba MS , Sall Y , Sougou NM , Diegane Tine JA , Mbacke Leye MM . medRxiv 2022 02 Introduction: Epidemiological surveillance (ES) which is a continuous systematic process of data collection, analysis and interpretation for decision-making is of paramount importance for a good health system. Thus, to contribute to the improvement of the health system in Senegal, a study of the functioning of the routine epidemiological surveillance system was conducted in Tambacounda from S1 to S53 of the year 2020. Methodology: A descriptive and analytical cross-sectional study was conducted from 1 to 17 July 2021. Comprehensive recruitment of the district's 44 health care points was carried out. Data collection was carried out through a questionnaire prepared, pre-tested and administered to the 44 heads of public and non-public health facilities. The analyses were carried out with R software version 4.0.5. Result(s): Of the 44 health facilities surveyed, 64% were public and 36% were non-public. The completeness and timeliness of the data were 100% and 97.5%, respectively. Suspected cases of tuberculosis were the most reported. For the providers surveyed (n=44), only 65.9% had knowledge of disease under epidemiological surveillance (DUES) and 93.2% managed suspected cases. On-site data analysis is only performed by 20.5% of providers. Only 38.6% of the service delivery point (SDP) had a health area card and the ES was under the responsibility of 77.3% of the paramedics. The training of ES officials was effective for only 45.5% of them. Despite the availability of dry tubes (69.8%), only 29.5% of PSD had COVID sampling equipment. The contribution of local authorities and technical and financial partners (TFP) to the SE was 22.7% and 29.5% respectively. There was a statistically significant link between public SDP with knowledge of DUES (p <0.001), display of case definitions (p <0.001), feedback of reported cases, knowledge of indicators (p <0.001), existence of a health area map (p <0.001), advocacy with authorities (p=0.003), staff training (p=0.002), availability of DUES vaccines (p <0.001), availability of notification form (p <0.001) and partner contribution to ES activities. Conclusion(s): Staff training, regular monitoring of ES activities with greater involvement of nonpublic structures, and the availability of inputs applied to the six pillars of the health system, are essential elements on which action must be taken. for an efficient ES system in the Tambacounda health district for the benefit of the country's health system. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license. |
Assessment of suspected COVID-19 deaths in nonhealthcare settings in Cote d'Ivoire, March 11 to July 31, 2020
Ndiaye SM , Tiembre I , Amani YMR , Zamina BYG , Vroh JBB , Diarrassouba M . Health Secur 2023 21 (4) 280-285 According to hospital records, 5 months after reporting its first case of COVID-19, Cote d'Ivoire reported only 102 deaths. We conducted a community mortality survey in the 13 districts where 95% of COVID-19 cases were reported to assess COVID-19 mortality in nonhealthcare settings. To identify suspected COVID-19 deaths in communities, we used data from social and administrative institutions, such as police and fire departments, funeral homes, and places of worship, whose functions include providing services related to deaths. Our survey identified 54 (17.6%) suspected COVID-19 deaths, which is more than half of the official reported number. Our study showed that in areas with low access to healthcare and poorly functioning death notification and registration systems, community-based data sources could be used to identify suspected COVID-19 deaths outside of the health sector. They can provide early warning data on events, such as an unusual number of community deaths or diseases. |
SARS-CoV-2 case detection using community event-based surveillance system-February-September 2020: lessons learned from Senegal
Seck O , Loko Roka J , Ndiaye M , Namageyo-Funa A , Abdoulaye S , Mangane A , Dieye NL , Ndoye B , Diop B , Ting J , Pasi O . BMJ Glob Health 2023 8 (6) The COVID-19 pandemic necessitated the rapid development and implementation of effective surveillance systems to detect and respond to the outbreak in Senegal. In this documentation, we describe the design and implementation of the Community Event-Based Surveillance (CEBS) system in Senegal to strengthen the existing Integrated Disease Surveillance and Response system. The CEBS system used a hotline and toll-free number to collect and triage COVID-19-related calls from the community. Data from the CEBS system were integrated with the national system for further investigation and laboratory testing. From February to September 2020, a total of 10 760 calls were received by the CEBS system, with 10 751 calls related to COVID-19. The majority of calls came from the Dakar region, which was the epicentre of the outbreak in Senegal. Of the COVID-19 calls, 50.2% were validated and referred to health districts for further investigation, and 25% of validated calls were laboratory-confirmed cases of SARS-CoV-2. The implementation of the CEBS system allowed for timely detection and response to potential COVID-19 cases, contributing to the overall surveillance efforts in the country. Lessons learned from this experience include the importance of decentralised CEBS, population sensitisation on hotlines and toll-free usage, and the potential role of Community Health Workers in triaging alerts that needs further analysis. This experience highlights the contribution of a CEBS system in Senegal and provides insights into the design and operation of such a system. The findings can inform other countries in strengthening their surveillance systems and response strategies. |
Seroprevalence of anti-SARS-CoV-2 antibodies in Senegal: a national population-based cross-sectional survey, between October and November 2020.
Talla C , Loucoubar C , Roka JL , Barry MA , Ndiaye S , Diarra M , Thiam MS , Faye O , Dia M , Diop M , Ndiaye O , Tall A , Faye R , Mbow AA , Diouf B , Diallo JP , Keita IM , Ndiaye M , Woudenberg T , White M , Ting J , Diagne CT , Pasi O , Diop B , Sall AA , Vigan-Womas I , Faye O . IJID Reg 2022 3 117-125 OBJECTIVES: A nationwide cross-sectional epidemiological survey was conducted to capture the true extent of coronavirus disease 2019 (COVID-19) exposure in Senegal. METHODS: Multi-stage random cluster sampling of households was performed between October and November 2020, at the end of the first wave of COVID-19 transmission. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies were screened using three distinct ELISA assays. Adjusted prevalence rates for the survey design were calculated for each test separately, and thereafter combined. Crude and adjusted prevalence rates based on test performance were estimated to assess the seroprevalence. As some samples were collected in high malaria endemic areas, the relationship between SARS-CoV-2 seroreactivity and antimalarial humoral immunity was also investigated. RESULTS: Of the 1463 participants included in this study, 58.8% were female and 41.2% were male; their mean age was 29.2 years (range 0.20-84.8.0 years). The national seroprevalence was estimated at 28.4% (95% confidence interval 26.1-30.8%). There was substantial regional variability. All age groups were impacted, and the prevalence of SARS-CoV-2 was comparable in the symptomatic and asymptomatic groups. An estimated 4 744 392 (95% confidence interval 4 360 164-5 145 327) were potentially infected with SARS-CoV-2 in Senegal, while 16 089 COVID-19 RT-PCR laboratory-confirmed cases were reported by the national surveillance. No correlation was found between SARS-CoV-2 and Plasmodium seroreactivity. CONCLUSIONS: These results provide a better estimate of SARS-CoV-2 dissemination in the Senegalese population. Preventive and control measures need to be reinforced in the country and especially in the south border regions. |
Feasibility and acceptability of nationwide HPV vaccine introduction in Senegal: findings from community-level cross-sectional surveys, 2020
Doshi RH , Casey RM , Adrien N , Ndiaye A , Brennan T , Roka JL , Bathily A , Ndiaye C , Li AnYie , Garon J , Badiane O , Diallo A , Loharikar A . PLoS Glob Public Health 2022 2 (4) e0000130 In Senegal, cervical cancer is the most common cancer among women and the leading cause of morbidity and mortality from all cancers. In 2018, Senegal launched a national human papillomavirus (HPV) vaccination program with Gavi, the Vaccine Alliance (Gavi), support. HPV vaccination was incorporated into the national immunization program as a two-dose schedule, with a 6-12-month interval, to nine-year-old girls via routine immunization (RI) services at health facilities, schools and community outreach services throughout the year. During February to March 2020, we conducted interviews to assess the awareness, feasibility, and acceptability of the HPV vaccination program with a cross-sectional convenience sample of healthcare workers (HCWs), school personnel, community healthcare workers (cHCWs), parents, and community leaders from 77 rural and urban health facility catchment areas. Participants were asked questions on HPV vaccine knowledge, delivery, training, and community acceptability of the program. We conducted a descriptive analysis stratified by respondent type. Data were collected from 465 individuals: 77 HCW, 78 school personnel, 78 cHCWs, 152 parents, and community leaders. The majority of HCWs (83.1%) and cHCWs (74.4%) and school personnel (57.7%) attended a training on HPV vaccine before program launch. Of all respondents, most (52.5-87.2%) were able to correctly identify the target population. The majority of respondents (60.2-77.5%) felt that the vaccine was very accepted or accepted in the community. Senegal's HPV vaccine introduction program, among the first national programs in the African region, was accepted by community stakeholders. Training rates were high, and most respondents identified the target population correctly. However, continued technical support is needed for the integration of HPV vaccination as a RI activity for this non-traditional age group. The Senegal experience can be a useful resource for countries planning to introduce the HPV vaccine. |
Sensitivity and specificity for malaria classification of febrile persons by rapid diagnostic test, microscopy, parasite DNA, histidine-rich protein 2, and IgG: Dakar, Senegal 2015
Badiane A , Thwing J , Williamson J , Rogier E , Diallo MA , Ndiaye D . Int J Infect Dis 2022 121 92-97 OBJECTIVES: Different methods detecting Plasmodium parasite infection or exposure are available, but systematic comparison of all these methodologies to predict malaria infection is lacking. Understanding the characteristics of respective tests is helpful to choose the most appropriate tests for epidemiological or research purposes. METHODS: Microscopy, RDT, and PCR was performed for 496 patients presenting with febrile illness in Dakar, Senegal in 2015. Blood samples had laboratory multiplex assays performed for IgG serology and detection of HRP2 antigen. Sensitivity (Se) and specificity (Sp) for different tests were calculated using PCR as the gold standard for detecting active infection. Modeling through latent class analysis (LCA) compared each test to a modeled gold standard for Se/Sp estimates. RESULTS: Against PCR, Se/Sp were 95.2%/93.7% for RDT, 90.4%/100.0% for microscopy, and 97.9%/48.1% for lab HRP2 detection. Compared to the modeled gold standard, Se of microscopy was 93.5%, and Se of RDT, PCR, and lab HRP2 detection were all greater than 99%. Se/Sp of IgG serology were substantially for detecting active infection. CONCLUSIONS: Compared to single tests, a combinatorial LCA approach of multiple biomarkers for detecting malaria infection from patient samples provides greater sensitivity and specificity for epidemiological estimates and research objectives. |
Cost of human papillomavirus vaccine delivery in a single-age cohort, routine-based vaccination program in Senegal
Brennan T , Hidle A , Doshi RH , An Q , Loharikar A , Casey R , Badiane O , Ndiaye A , Diallo A , Loko Roka J , Mejia N , Abimbola T . Vaccine 2021 40 Suppl 1 A77-A84 INTRODUCTION: In 2018, Senegal introduced human papillomavirus (HPV) vaccine into its routine immunization program for all nine-year-old girls nationwide. We evaluated the costs of Senegal's introduction of HPV vaccine via this delivery approach. METHODS: We conducted a retrospective, incremental, ingredients-based cost evaluation from the provider perspective. The study timeframe included Senegal's first planning meeting in 2018 through data collection in early 2020. We collected costs from all involved units at the national and regional levels. A multi-stage cluster sampling approach was used to obtain a nationally representative sample of districts and health facilities. Weights were applied to costs from sampled units to estimate costs across all units. The cost evaluation was based on four dimensions: program activity, resource input, payer, and administrative level. Total costs were divided by the number of HPV doses administered to determine cost per dose and per dimension. RESULTS: Excluding vaccine program activity costs, the total financial and economic delivery costs of Senegal's HPV vaccination program were US$ 1,152,351 and US$ 2,838,466, respectively (US$ 3.07 and US$ 7.56 per dose, respectively). A total of 375,608 HPV vaccine doses were administered during the cost evaluation. Training and per diem represented the largest shares of financial costs. Service delivery and personnel time accounted for the largest shares of economic costs. By administrative level, district and health facility levels had the largest shares of financial and economic costs, respectively. Senegal's Ministry of Health accounted for the largest share of financial and economic costs. Including vaccine program activity costs (US$ 4.68/per dose), the total financial cost was US$ 2,911,343 (US$ 7.75 per dose). CONCLUSION: This cost evaluation can support Senegal's future vaccine introductions and inform other countries planning to introduce HPV vaccine nationwide. These findings support previous costing studies which anticipated potential economies of scale during the transition from HPV vaccine pilot demonstration projects to national introduction. |
Prevalence and genetic characterization of noroviruses in children with acute gastroenteritis in Senegal, 2007-2010.
Kebe O , Fernandez-Garcia MD , Zinsou BE , Diop A , Fall A , Ndiaye N , Vinjé J , Ndiaye K . J Med Virol 2021 94 (6) 2640-2644 Norovirus is the leading cause of sporadic and epidemic acute gastroenteritis (AGE) in children and adults around the world. We investigated the molecular diversity of noroviruses in a paediatric population in Senegal between 2007-2010 prior to rotavirus vaccine implementation. Stool samples were collected from 599 children under 5 years of age consulting for AGE in a hospital in Dakar. Specimens were screened for noroviruses using the Allplex™ GI-Virus Assay. Positive samples were genotyped after sequencing of conventional RT-PCR products. Noroviruses were detected in 79 (13.2%) of the children, with GII.4 (64%) and GII.6 (10%) as the most frequently identified genotypes. Our study describes the distribution of genotypes between 2007 and 2010 and should be a baseline for comparison with more contemporary studies. This could help decision makers on possible choices of norovirus vaccines in the event of future introduction. This article is protected by copyright. All rights reserved. |
Efficacy of Artemether-Lumefantrine for the Treatment of Plasmodium falciparum Malaria in Bohicon and Kandi, Republic of Benin, 2018-2019.
Kpemasse A , Dagnon F , Saliou R , Yarou Maye AS , Affoukou CD , Zoulkaneri A , Guézo-Mévo B , Moriarty LF , Ndiaye YD , Garba MN , Deme AB , Ndiaye D , Hounto AO . Am J Trop Med Hyg 2021 105 (3) 670-676 In 2005, artemether-lumefantrine (AL), an artemisinin-based combination therapy, was introduced as the first-line treatment of uncomplicated Plasmodium falciparum malaria in Benin. Per World Health Organization recommendations to monitor the efficacy of antimalarial treatment, we conducted a therapeutic efficacy study with AL for uncomplicated P. falciparum malaria in Bohicon and Kandi, Benin, from 2018 to 2019. Febrile patients aged 6 to 59 months with confirmed P. falciparum monoinfection received supervised doses of AL for 3 days. We monitored patients clinically and parasitologically on days 1, 2, 3, 7, 14, 21, and 28. A molecular analysis to detect mutations in the P. falciparum Kelch propeller gene (Pfk13) gene was carried out on day 0 samples. A total of 205 patients were included in the study. In Bohicon, the uncorrected adequate clinical and parasitological response (ACPR) proportion was 91.3% (95% confidence interval [CI]: 84.6-95.8%), whereas in Kandi this proportion was 96.7% (95% CI: 90.6-99.3%). Genotype-corrected ACPR proportions were 96.3% (95% CI: 90.9-99.0%) and 96.7% (95% CI: 90.6-99.3%) in Bohicon and Kandi, respectively. On day 3, 100% of patients in Bohicon and 98.9% of patients in Kandi had undetectable parasitemia. The C580Y mutation in the Pfk13 gene was not observed. AL remains effective for P. falciparum malaria in these two sites in Benin. Monitoring antimalarial efficacy and prevalence of molecular-resistance markers in Benin should be continued to allow for early detection of antimalarial resistance and to guide treatment policies. |
Increasing rates of methamphetamine/amphetamine-involved overdose hospitalizations in Washington State, 2010-2017
Njuguna H , Gong J , Hutchinson K , Ndiaye M , Sabel J , Wasserman C . Addict Behav Rep 2021 14 100353 BACKGROUND AND AIMS: In the United States, overdose deaths resulting from methamphetamine and other amphetamine-type stimulants (METH/AMPH) have been increasing. We describe rates and characterize patients hospitalized after a METH/AMPH-involved overdose in Washington State, to guide prevention and control measures. DESIGN SETTING PARTICIPANTS: We conducted a trend analysis of hospitalized Washington State residents aged ≥15 years who received a METH/AMPH-involved overdose diagnosis in Washington's civilian hospitals and reported in the Comprehensive Hospital Abstract Reporting System. MEASUREMENTS: We used Joinpoint regression analysis to study trends in rates of hospitalized patients who received a METH/AMPH-involved overdose diagnosis during 2010-2017. We used 2016-2017 data to describe characteristics of patients with nonfatal and fatal outcomes and used chi-square test (for categorical variables) and Wilcoxon rank-sum test (for continuous variables) to compare characteristics of patients by outcome. FINDINGS: During 2010-2017, 3587 patients were hospitalized and received a METH/AMPH-involved overdose diagnosis. The age-adjusted rate for METH/AMPH-involved overdose hospitalization increased from 6.3/100,000 persons in 2010 to 8.5/100,000 persons in 2017. Patients aged ≥55 years had the greatest increase in rate of overdose hospitalizations. Among these patients, 86% also had a substance use disorder diagnosis involving substances other than METH/AMPH, and 35% experienced a polysubstance overdose. CONCLUSIONS: We observed increasing rates of METH/AMPH-involved overdose hospitalizations in Washington State, particularly among persons aged ≥55 years. Approximately a third of patients also experienced a polysubstance overdose, which can be considered when designing interventions to address increasing rates of overdose hospitalizations in Washington State. |
Delivering health interventions to women, children, and adolescents in conflict settings: what have we learned from ten country case studies
Singh NS , Ataullahjan A , Ndiaye K , Das JK , Wise PH , Altare C , Ahmed Z , Sami S , Akik C , Tappis H , Mirzazada S , Garcés-Palacio IC , Ghattas H , Langer A , Waldman RJ , Spiegel P , Bhutta ZA , Blanchet K . Lancet 2021 397 (10273) 533-542 Armed conflict disproportionately affects the morbidity, mortality, and wellbeing of women, newborns, children, and adolescents. Our study presents insights from a collection of ten country case studies aiming to assess the provision of sexual, reproductive, maternal, newborn, child, and adolescent health and nutrition interventions in ten conflict-affected settings in Afghanistan, Colombia, Democratic Republic of the Congo, Mali, Nigeria, Pakistan, Somalia, South Sudan, Syria, and Yemen. We found that despite large variations in contexts and decision making processes, antenatal care, basic emergency obstetric and newborn care, comprehensive emergency obstetric and newborn care, immunisation, treatment of common childhood illnesses, infant and young child feeding, and malnutrition treatment and screening were prioritised in these ten conflict settings. Many lifesaving women's and children's health (WCH) services, including the majority of reproductive, newborn, and adolescent health services, are not reported as being delivered in the ten conflict settings, and interventions to address stillbirths are absent. International donors remain the primary drivers of influencing the what, where, and how of implementing WCH interventions. Interpretation of WCH outcomes in conflict settings are particularly context-dependent given the myriad of complex factors that constitute conflict and their interactions. Moreover, the comprehensiveness and quality of data remain limited in conflict settings. The dynamic nature of modern conflict and the expanding role of non-state armed groups in large geographic areas pose new challenges to delivering WCH services. However, the humanitarian system is creative and pluralistic and has developed some novel solutions to bring lifesaving WCH services closer to populations using new modes of delivery. These solutions, when rigorously evaluated, can represent concrete response to current implementation challenges to modern armed conflicts. |
Genetic evidence for imported malaria and local transmission in Richard Toll, Senegal.
Daniels RF , Schaffner SF , Dieye Y , Dieng G , Hainsworth M , Fall FB , Diouf CN , Ndiop M , Cisse M , Gueye AB , Sarr O , Guinot P , Deme AB , Bei AK , Sy M , Thwing J , MacInnis B , Earle D , Guinovart C , Sene D , Hartl DL , Ndiaye D , Steketee RW , Wirth DF , Volkman SK . Malar J 2020 19 (1) 276 BACKGROUND: Malaria elimination efforts can be undermined by imported malaria infections. Imported infections are classified based on travel history. METHODS: A genetic strategy was applied to better understand the contribution of imported infections and to test for local transmission in the very low prevalence region of Richard Toll, Senegal. RESULTS: Genetic relatedness analysis, based upon molecular barcode genotyping data derived from diagnostic material, provided evidence for both imported infections and ongoing local transmission in Richard Toll. Evidence for imported malaria included finding that a large proportion of Richard Toll parasites were genetically related to parasites from Thiès, Senegal, a region of moderate transmission with extensive available genotyping data. Evidence for ongoing local transmission included finding parasites of identical genotype that persisted across multiple transmission seasons as well as enrichment of highly related infections within the households of non-travellers compared to travellers. CONCLUSIONS: These data indicate that, while a large number of infections may have been imported, there remains ongoing local malaria transmission in Richard Toll. These proof-of-concept findings underscore the value of genetic data to identify parasite relatedness and patterns of transmission to inform optimal intervention selection and placement. |
Proactive community case management in Senegal 2014-2016: a case study in maximizing the impact of community case management of malaria
Gaye S , Kibler J , Ndiaye JL , Diouf MB , Linn A , Gueye AB , Fall FB , Ndiop M , Diallo I , Cisse M , Ba M , Thwing J . Malar J 2020 19 (1) 166 The Senegal National Malaria Control Programme (NMCP) introduced home-based malaria management for all ages, with diagnosis by rapid diagnostic test (RDT) and treatment with artemisinin-based combination therapy (ACT) in 2008, expanding to over 2000 villages nationwide by 2014. With prise en charge a domicile (PECADOM), community health workers (CHWs) were available for community members to seek care, but did not actively visit households to find cases. A trial of a proactive model (PECADOM Plus), in which CHWs visited all households in their village weekly during transmission season to identify fever cases and offer case management, in addition to availability during the week for home-based management, found that CHWs detected and treated more cases in intervention villages, while the number of cases detected weekly decreased over the transmission season. The NMCP scaled PECADOM Plus to three districts in 2014 (132 villages), to a total of six districts in 2015 (246 villages), and to a total of 16 districts in 2016 (708 villages). A narrative case study with programmatic results is presented. During active sweeps over approximately 20 weeks, CHWs tested a mean of 77 patients per CHW in 2014, 89 patients per CHW in 2015, and 90 patients per CHW in 2016, and diagnosed a mean of 61, 61 and 43 patients with malaria per CHW in 2014, 2015 and 2016, respectively. The number of patients who sought care between sweeps increased, with a 104% increase in the number of RDTs performed and a 77% increase in the number of positive tests and patients treated with ACT during passive case detection. While the number of CHWs increased 7%, the number of patients receiving an RDT increased by 307% and the number of malaria cases detected and treated by CHWs increased 274%, from the year prior to PECADOM Plus introduction to its first year of implementation. Based on these results, approximately 700 additional CHWs in 24 new districts were added in 2017. This case study describes the process, results and lessons learned from Senegal's implementation of PECADOM Plus, as well as guidance for other programmes considering introduction of this innovative strategy. |
Community-based surveillance in Cote d'Ivoire
Clara A , Ndiaye SM , Joseph B , Nzogu MA , Coulibaly D , Alroy KA , Gourmanon DC , Diarrassouba M , Toure-Adechoubou R , Houngbedji KA , Attiey HB , Balajee SA . Health Secur 2020 18 S23-s33 Community-based surveillance can be an important component of early warning systems. In 2016, the Cote d'Ivoire Ministry of Health launched a community-based surveillance project in 3 districts along the Guinea border. Community health workers were trained in detection and immediate reporting of diseases and events using a text-messaging platform. In December 2017, surveillance data from before and after implementation of community-based surveillance were analyzed in intervention and control districts. A total of 3,734 signals of priority diseases and 4,918 unusual health events were reported, of which 420 were investigated as suspect diseases and none were investigated as unusual health events. Of the 420 suspected cases reported, 23 (6%) were laboratory confirmed for a specific pathogen. Following implementation of community-based surveillance, 5-fold and 8-fold increases in reporting of suspected measles and yellow fever clusters, respectively, were documented. Reporting incidence rates in intervention districts for suspected measles, yellow fever, and acute flaccid paralysis were significantly higher after implementation, with a difference of 29.2, 19.0, and 2.5 cases per 100,000 person-years, respectively. All rate differences were significantly higher in intervention districts (p < 0.05); no significant increase in reporting was noted in control districts. These findings suggest that community-based surveillance strengthened detection and reporting capacity for several suspect priority diseases and events. However, the surveillance program was very sensitive, resulting in numerous false-positives. Learning from the community-based surveillance implementation experience, the ministry of health is revising signal definitions to reduce sensitivity and increase specificity, reviewing training materials, considering scaling up sustainable reporting platforms, and standardizing community health worker roles. |
Analysis of anti-Plasmodium IgG profiles among Fulani nomadic pastoralists in northern Senegal to assess malaria exposure
Seck MC , Thwing J , Badiane AS , Rogier E , Fall FB , Ndiaye PI , Diongue K , Mbow M , Ndiaye M , Diallo MA , Gomis JF , Mbaye A , Ndiaye T , Gaye A , Sy M , Deme AB , Ndiaye YD , Ndiaye D . Malar J 2020 19 (1) 15 BACKGROUND: Northern Senegal is a zone of very low malaria transmission, with an annual incidence of < 5/1000 inhabitants. This area, where the Senegal National Malaria Control Programme has initiated elimination activities, hosts Fulani, nomadic, pastoralists that spend the dry season in the south where malaria incidence is higher (150-450/1000 inhabitants) and return to the north with the first rains. Previous research demonstrated parasite prevalence of < 1% in this Fulani population upon return from the south, similar to that documented in the north in cross-sectional surveys. METHODS: A modified snowball sampling survey of nomadic pastoralists was conducted in five districts in northern Senegal during September and October 2014. Demographic information and dried blood spots were collected. Multiplex bead-based assays were used to assess antibody responses to merozoite surface protein (MSP-119) antigen of the four primary Plasmodium species, as well as circumsporozoite protein (CSP) and liver stage antigen (LSA-1) of Plasmodium falciparum. RESULTS: In the five study districts, 1472 individuals were enrolled, with a median age of 22 years (range 1 to 80 years). Thirty-two percent of subjects were under 14 years and 57% were male. The overall seroprevalence of P. falciparum MSP-119, CSP and LSA-1 antibodies were 45, 12 and 5%, respectively. Plasmodium falciparum MSP-119 antibody responses increased significantly with age in all study areas, and were significantly higher among males. The highest seroprevalence to P. falciparum antigens was observed in the Kanel district (63%) and the lowest observed in Podor (28%). Low seroprevalence was observed for non-falciparum species in all the study sites: 0.4, 0.7 and 1.8%, respectively, for Plasmodium ovale, Plasmodium vivax and Plasmodium malariae MSP-1. Antibody responses to P. vivax were observed in all study sites except Kanel. CONCLUSION: Prevalence of P. falciparum MSP-119 antibodies and increases by study participant age provided data for low levels of exposure among this transient nomadic population. In addition, antibody responses to P. falciparum short half-life markers (CSP and LSA-1) and non-falciparum species were low. Further investigations are needed to understand the exposure of the Fulani population to P. vivax. |
Impact of 13-valent pneumococcal conjugate vaccine on meningitis and pneumonia hospitalizations in children aged <5 years in Senegal, 2010-2016
Faye PM , Sonko MA , Diop A , Thiongane A , Ba ID , Spiller M , Ndiaye O , Dieye B , Mwenda JM , Sow AI , Diop B , Diallo A , Farrar JL . Clin Infect Dis 2019 69 S66-s71 BACKGROUND: Senegal introduced a 13-valent pneumococcal conjugate vaccine (PCV13) in October 2013, given at 6, 10, and 14 weeks of age. We document trends of meningitis and pneumonia after the PCV13 introduction. METHODS: From October 2010-October 2016, hospitalization data for clinical meningitis and pneumonia in children aged <5 years were collected from logbooks at a large, tertiary, pediatric hospital in Dakar. We used a set of predetermined keywords to define hospitalizations for extraction from hospital registers. We conducted a time-series analysis and compared hospitalizations before and after the PCV13 introduction, accounting for seasonality. The initial PCV13 uptake period (October 2013-September 2014) was considered to be transitional and was excluded. RESULTS: Over the 7-year period, 1836 and 889 hospitalizations with a discharge diagnosis of pneumonia and meningitis, respectively, occurred in children aged <5 years. In children aged <12 months, a small, significant reduction in pneumonia was observed post-PCV13 (-3.8%, 95% confidence interval [CI] -1.5 to -5.9%). No decline was observed among children aged 12-59 months (-0.7%, 95% CI -0.8 to 2.2%). Meningitis hospitalizations remained stable for children aged <12 months (1.8%, 95% CI -0.9 to 4.4%) and 12-59 months (-0.5%, 95% CI -3.6 to 2.6%). CONCLUSIONS: We used data from 1 hospital to detect a small, significant reduction in all-cause pneumonia hospitalizations 2 years post-PCV13 introduction in infants; the same trend was not measurable in children aged 12-59 months or in meningitis cases. There is a need for continued surveillance to assess the long-term impact of sustained PCV13 use and to monitor how pneumococcus is causing disease in the meningitis belt. |
Serological data shows low levels of chikungunya exposure in Senegalese nomadic pastoralists
Seck MC , Badiane AS , Thwing J , Moss D , Fall FB , Gomis JF , Deme AB , Diongue K , Sy M , Mbaye A , Ndiaye T , Gaye A , Ndiaye YD , Diallo MA , Ndiaye D , Rogier E . Pathogens 2019 8 (3) The chikungunya virus (CHIKV) is spread by Aedes aegypti and Ae. albopictus mosquitos worldwide; infection can lead to disease including joint pain, fever, and rash, with some convalescent persons experiencing chronic symptoms. Historically, CHIKV transmission has occurred in Africa and Asia, but recent outbreaks have taken place in Europe, Indonesia, and the Americas. From September to October 2014, a survey was undertaken with nomadic pastoralists residing in the northeast departments of Senegal. Blood dried on filter paper (dried blood spots; DBS) were collected from 1465 participants of all ages, and assayed for Immunoglobulin G (IgG) antibodies against CHIKV E1 antigen by a bead-based multiplex assay. The overall seroprevalence of all participants to CHIKV E1 was 2.7%, with no persons under 10 years of age found to be antibody positive. Above 10 years of age, clear increases of seroprevalence and IgG levels were observed with increasing age; 7.6% of participants older than 50 years were found to be positive for anti-CHIKV IgG. Reported net ownership, net usage, and gender were all non-significant explanatory variables of seropositivity. These data show a low-level historical exposure of this pastoralist population to CHIKV, with no evidence of recent CHIKV transmission in the past decade. |
Immunogenicity and safety of MF59-adjuvanted and full-dose unadjuvanted trivalent inactivated influenza vaccines among vaccine-naive children in a randomized clinical trial in rural Senegal
Diallo A , Victor JC , Feser J , Ortiz JR , Kanesa-Thasan N , Ndiaye M , Diarra B , Cheikh S , Diene D , Ndiaye T , Ndiaye A , Lafond KE , Widdowson MA , Neuzil KM . Vaccine 2018 36 (43) 6424-6432 INTRODUCTION: Effective, programmatically suitable influenza vaccines are needed for low-resource countries. MATERIALS AND METHODS: This phase II, placebo-controlled, randomized safety and immunogenicity trial (NCT01819155) was conducted in Senegal using the 2012-2013 Northern Hemisphere trivalent influenza vaccine (TIV) formulation. Participants were allocated in a 2:2:1 ratio to receive TIV (full-dose for all age groups), adjuvanted TIV (aTIV), or placebo. Participants were stratified into age groups: 6-11, 12-35, and 36-71months. All participants were vaccine-naive and received two doses of study vaccine 4weeks apart. The two independent primary objectives were to estimate the immunogenicity of TIV and of aTIV as the proportion of children with a hemagglutination inhibition (HI) antibody titer of >/=1:40 to each vaccine strain at 28days post-dose two. Safety was evaluated by solicited local and systemic reactions, unsolicited adverse events, and serious adverse events. RESULTS: 296 children received TIV, aTIV, or placebo, and 235 were included in the final analysis. After two doses, children aged 6-11, 12-35, and 36-71months receiving TIV had HI titers >/=1:40 against A/H1N1 (73.1%, 94.1%, and 97.0%), A/H3N2 (96.2%, 100.0%, and 100.0%), and B (80.8%, 97.1%, and 97.0%), respectively. After two doses, 100% children aged 6-11, 12-35, and 36-71months receiving aTIV had >/=1:40 titers against A/H1N1, A/H3N2, and B. After a single dose, the aTIV response was comparable to or greater than the TIV response for all vaccine strains. TIV and aTIV reactogenicity were similar, except for mild elevation in temperature (37.5-38.4 degrees C) which occurred more frequently in aTIV than TIV after each vaccine dose. TIV and aTIV had similarly increased pain/tenderness at the injection site compared to placebo. CONCLUSIONS: Both aTIV and full-dose TIV were well-tolerated and immunogenic in children aged 6-71months. These vaccines may play a role in programmatically suitable strategies to prevent influenza in low-resource settings. |
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