Publications by authors named "Ngayo Sy"

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.

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  • Genetic surveillance of Plasmodium falciparum can help National Malaria Control Programmes estimate parasite transmission using metrics like multi-strain infections and infection complexity, despite uncertainties about their ability to directly predict clinical incidence.
  • In a study involving 3,147 clinical infections across Senegal from 2012-2020, researchers used genetic analysis to correlate genetic metrics with malaria incidence at different clinic sites.
  • Results indicated that genetic metrics reliably predicted incidence when transmission was high (over 10 cases per 1,000 annually), but showed reversed correlations at lower transmission levels, suggesting a limit to the use of genetics in estimating incidence during low transmission periods.
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The worldwide decline in malaria incidence is revealing the extensive burden of non-malarial febrile illness (NMFI), which remains poorly understood and difficult to diagnose. To characterize NMFI in Senegal, we collected venous blood and clinical metadata in a cross-sectional study of febrile patients and healthy controls in a low malaria burden area. Using 16S and untargeted sequencing, we detected viral, bacterial, or eukaryotic pathogens in 23% (38/163) of NMFI cases.

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Genetic surveillance of the 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.

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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.

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  • Researchers studied non-malarial febrile illness (NMFI) in Senegal, finding it is hard to understand and diagnose.
  • In their study, they found that 29% of NMFI cases had different germs, mostly bacteria, while some cases had viruses.
  • They created a model to help doctors better identify NMFI based on symptoms and health signs, showing that better testing is really needed.
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  • Scientists are studying how to use parasite genetics to help control malaria in Senegal.
  • They discovered that having multiple different types of parasites in one person can predict local malaria outbreaks.
  • Most related parasites in the country form a big family, which could help identify where malaria is spreading and if certain drugs are becoming less effective against it.
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Multiple-strain (polygenomic) infections are a ubiquitous feature of parasite population genetics. Under simple assumptions of superinfection, polygenomic infections are hypothesized to be the result of multiple infectious bites. As a result, polygenomic infections have been used as evidence of repeat exposure and used to derive genetic metrics associated with high transmission intensity.

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  • Researchers found that the LARGE gene is crucial for how Lassa virus binds and enters human cells, linking it to natural selection in populations in Nigeria, particularly the Yoruba.
  • They suggest that the rise of diseases like Lassa fever is more about increased detection capabilities than the emergence of new viruses, indicating humans may have been exposed to these pathogens for longer than thought.
  • This groundwork inspired the Sentinel project, aimed at early detection and characterization of pathogens globally through its core strategies of detection, information sharing, and empowering public health systems to enhance pandemic preparedness.
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Dengue virus is a major and rapidly growing public health concern in tropic and subtropic regions across the globe. In late 2018, Senegal experienced its largest dengue virus outbreak to date, covering several regions. However, little is known about the genetic diversity of dengue virus (DENV) in Senegal.

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As effective onchocerciasis control efforts in Africa transition to elimination efforts, different diagnostic tools are required to support country programs. Senegal, with its long standing, successful control program, is transitioning to using the SD BIOLINE Onchocerciasis IgG4 (Ov16) rapid test over traditional skin snip microscopy. The aim of this study is to demonstrate the feasibility of integrating the Ov16 rapid test into onchocerciasis surveillance activities in Senegal, based on the following attributes of acceptability, usability, and cost.

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Background: The monitoring of Plasmodium falciparum sensitivity to anti-malarial drugs is a necessity for effective case management of malaria. This species is characterized by a strong resistance to anti-malarial drugs. In Senegal, the first cases of chloroquine resistance were reported in the Dakar region in 1988 with nearly 7% population prevalence, reaching 47% by 1990.

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  • * In surveys across three districts, most participants tested negative for LF and onchocerciasis, but one district showed ongoing LF transmission and recent indications of onchocerciasis.
  • * The findings highlight the need for improved methods to evaluate the transmission of LF and onchocerciasis in co-endemic areas, which could help inform decisions on when to stop mass drug administration safely.
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In 2006, artemether-lumefantrine (AL) became the first-line treatment of uncomplicated malaria in Senegal, Mali, and the Gambia. To monitor its efficacy, between August 2011 and November 2014, children with uncomplicated Plasmodium falciparum malaria were treated with AL and followed up for 42 days. A total of 463 subjects were enrolled in three sites (246 in Senegal, 97 in Mali, and 120 in Gambia).

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Background: The use of artemisinin as a monotherapy resulted in the emergence of artemisinin resistance in 2005 in Southeast Asia. Monitoring of artemisinin combination therapy (ACT) is critical in order to detect and prevent the spread of resistance in endemic areas. Ex vivo studies and genotyping of molecular markers of resistance can be used as part of this routine monitoring strategy.

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Understanding genetic causes and effects of speciation in sympatric populations of sexually reproducing eukaryotes is challenging, controversial, and of practical importance for controlling rapidly evolving pests and pathogens. The major African malaria vector mosquito Anopheles gambiae sensu stricto (s.s.

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With the paradigm shift from the reduction of morbidity and mortality to the interruption of transmission, the focus of malaria control broadens from symptomatic infections in children ≤5 years of age to include asymptomatic infections in older children and adults. In addition, as control efforts intensify and the number of interventions increases, there will be decreases in prevalence, incidence and transmission with additional decreases in morbidity and mortality. Expected secondary consequences of these changes include upward shifts in the peak ages for infection (parasitemia) and disease, increases in the ages for acquisition of antiparasite humoral and cellular immune responses and increases in false-negative blood smears and rapid diagnostic tests.

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The study sites for the West African ICEMR are in three countries (The Gambia, Senegal, Mali) and are located within 750 km of each other. In addition, the National Malaria Control Programmes of these countries have virtually identical policies: (1) Artemisinin Combination Therapies (ACTs) for the treatment of symptomatic Plasmodium falciparum infection, (2) Long-Lasting Insecticide-treated bed Nets (LLINs) to reduce the Entomololgic Inoculation Rate (EIR), and (3) sulfadoxine-pyrimethamine for the Intermittent Preventive Treatment of malaria during pregnancy (IPTp). However, the prevalence of P.

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