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63 result(s) for "Seye, M."
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Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes
Schistosomes are dioecious parasitic flatworms, which live in the vasculature of their mammalian definitive hosts. They are the causative agent of schistosomiasis, a disease of considerable medical and veterinary importance in tropical and subtropical regions. Schistosomes undergo a sexual reproductive stage within their mammalian host enabling interactions between different species, which may result in hybridization if the species involved are phylogenetically close. In Senegal, three closely related species in the Schistosoma haematobium group are endemic: S. haematobium, which causes urogenital schistosomiasis in humans, and S. bovis and S. curassoni, which cause intestinal schistosomiasis in cows, sheep and goats. Large-scale multi-loci molecular analysis of parasite samples collected from children and domestic livestock across Senegal revealed that interactions and hybridization were taking place between all three species. Evidence of hybridization between S. haematobium/S. curassoni and S. haematobium/S. bovis was commonly found in children from across Senegal, with 88% of the children surveyed in areas of suspected species overlap excreting hybrid miracidia. No S. haematobium worms or hybrids thereof were found in ruminants, although S. bovis and S. curassoni hybrid worms were found in cows. Complementary experimental mixed species infections in laboratory rodents confirmed that males and females of each species readily pair and produce viable hybrid offspring. THESE DATA PROVIDE INDISPUTABLE EVIDENCE FOR: the high occurrence of bidirectional hybridization between these Schistosoma species; the first conclusive evidence for the natural hybridisation between S. haematobium and S. curassoni; and demonstrate that the transmission of the different species and their hybrids appears focal. Hybridization between schistosomes has been known to influence the disease epidemiology and enhance phenotypic characteristics affecting transmission, morbidity and drug sensitivity. Therefore, understanding and monitoring such inter-species interactions will be essential for optimizing and evaluating control strategies across such potential hybrid zones.
Implementing a pragmatic randomised controlled trial in a humanitarian setting: lessons learned from the TISA trial
Introduction High-quality evidence is crucial for guiding effective humanitarian responses, yet conducting rigorous research, particularly randomised controlled trials, in humanitarian crises remains challenging. The TISA (“traitement intégré de la sous-nutrition aiguë”) trial aimed to evaluate the impact of a Water, Sanitation and Hygiene (WASH) intervention on the standard national treatment of uncomplicated Severe Acute Malnutrition (SAM) in children aged 6–59 months. Implemented in two northern Senegalese regions from December 22, 2021, to February 20, 2023, the trial faced numerous challenges, which this paper explores along with the lessons learned. Methods The study utilised trial documentation, including field reports, meeting minutes, training plans, operational monitoring data and funding proposals, to retrace the trial timeline, identify challenges and outline implemented solutions. Contributions from all TISA key staff—current and former, field-based and headquarters—were essential for collecting and interpreting information. Challenges were categorised as internal (within the TISA consortium) or external (broader contextual issues). Results The TISA trial, executed by a consortium of academic, operational, and community stakeholders, enrolled over 2000 children with uncomplicated SAM across 86 treatment posts in a 28,000 km 2 area. The control group received standard outpatient SAM care, while the intervention group also received a WASH kit and hygiene promotion. Initially planned to start in April 2019 for 12 months, the trial faced a 30-month delay and was extended to 27 months due to challenges like the COVID-19 pandemic, national strikes, health system integration issues and weather-related disruptions. Internal challenges included logistics, staffing, data management, funding and aligning diverse stakeholder priorities. Discussion and conclusion Despite these obstacles, the trial concluded successfully, underscoring the importance of tailored monitoring, open communication, transparency and community involvement. Producing high-quality evidence in humanitarian contexts demands extensive preparation and strong coordination among local and international researchers, practitioners, communities, decision-makers and funders from the study’s inception. Trial registration Clinicaltrials.gov NCT04667767 .
Toxicological study of pesticides in air and precipitations of Paris by means of a bioluminescence method
A detailed toxicological study on several pesticides, including chlorothalonil, cyprodynil, dichlobénil, pendimethaline, trifluraline, and α-endosulfan, present at trace levels in air and total atmospheric precipitations of Paris is presented. The pesticides contained in the atmospheric samples, collected during sampling campaigns in February-March 2007, are identified and quantified by a high-performance liquid chromatographic (HPLC)-UV detection method. The toxicity measurements are performed by means of the Microtox® bioluminescence method, based on the evaluation of the bioluminescence inhibition of the Vibrio fischeri marine bacteria at two exposure times to the pesticide solutions. The specific toxicity, corresponding to the particular toxicity of the compound under study and represented by the EC₅₀ parameter, is determined for these pesticides. Also, the global toxicity, which is the toxicity of all micro-pollutants present in the sample under study, is estimated for the extracts of air and atmospheric precipitation (rainwater) samples. The specific toxicities strongly vary with the nature of the pesticide, the EC₅₀ parameter values being comprised between 0.17 and 0.83 mg/mL and 0.15 and 0.66 mg/mL, respectively, for exposure times of 5 and 15 min. The importance of the atmospheric samples' global toxicity and the respective contribution of the toxic potency of the various pesticides contained in these samples are discussed. [graphic removed]
Genetic Diversity within Schistosoma haematobium: DNA Barcoding Reveals Two Distinct Groups
Schistosomiasis in one of the most prevalent parasitic diseases, affecting millions of people and animals in developing countries. Amongst the human-infective species S. haematobium is one of the most widespread causing urogenital schistosomiasis, a major human health problem across Africa, however in terms of research this human pathogen has been severely neglected. To elucidate the genetic diversity of Schistosoma haematobium, a DNA 'barcoding' study was performed on parasite material collected from 41 localities representing 18 countries across Africa and the Indian Ocean Islands. Surprisingly low sequence variation was found within the mitochondrial cytochrome oxidase subunit I (cox1) and the NADH-dehydrogenase subunit 1 snad1). The 61 haplotypes found within 1978 individual samples split into two distinct groups; one (Group 1) that is predominately made up of parasites from the African mainland and the other (Group 2) that is made up of samples exclusively from the Indian Ocean Islands and the neighbouring African coastal regions. Within Group 1 there was a dominance of one particular haplotype (H1) representing 1574 (80%) of the samples analyzed. Population genetic diversity increased in samples collected from the East African coastal regions and the data suggest that there has been movement of parasites between these areas and the Indian Ocean Islands. The high occurrence of the haplotype (H1) suggests that at some point in the recent evolutionary history of S. haematobium in Africa the population may have passed through a genetic 'bottleneck' followed by a population expansion. This study provides novel and extremely interesting insights into the population genetics of S. haematobium on a large geographic scale, which may have consequence for control and monitoring of urogenital schistosomiasis.
Mapping QTLs for early leaf spot resistance and yield component traits using an interspecific AB-QTL population in peanut
Early leaf spot (ELS), caused by Passalora personata (syn. Cercospora arachidicola ), is a highly damaging peanut disease worldwide. While there are limited sources of resistance in cultivated peanut cultivars, wild relatives carry alleles for strong resistance, making them a valuable strategic resource for peanut improvement. So far, only a few wild diploid species have been utilized to transfer resistant alleles to cultivars. To mitigate the risk of resistance breakdown by pathogens, it is important to diversify the sources of resistance when breeding for disease resistance. In this study, we created an AB-QTL population by crossing an induced allotetraploid (IpaCor1), which combines the genomes of the diploid species Arachis ipaënsis and A. correntina , with the susceptible cultivar Fleur11. A. correntina has been reported to possess strong resistance to leaf spot diseases. The AB-QTL population was genotyped with the Axiom-Arachis 48K SNPs and evaluated for ELS resistance under natural infestation over three years in Senegal. Marker/trait associations enabled the mapping of five QTLs for ELS resistance on chromosomes A02, A03, A08, B04, and B09. Except for the QTL on chromosome B09, the wild species contributed favorable alleles at all other QTLs. One genomic region on chromosome A02 contained several relevant QTLs, contributing to ELS resistance, earliness, and increased biomass yield, potentially allowing marker-assisted selection to introduce this region into elite cultivars. This study’s findings have aided in diversifying the sources of resistance to ELS disease and other important agronomic traits, providing another compelling example of the value of peanut wild species in improving cultivated peanut.
Usefulness of cyclodextrin media for the determination of α-cypermethrin by photochemically induced fluorescence: analytical applications to natural waters
The photochemically induced fluorescence (PIF) spectral properties of α-cypermethrin in organic solvents (hexane, dichloromethane, acetonitrile, ethanol) and in cyclodextrin aqueous solutions (β-CD and 2-hydroxypropyl-β-CD, 2-HP-β-CD) were investigated. The photolysis kinetics of α-cypermethrin were evaluated in the various media. The PIF signal was found to be significantly enhanced in the CD media relative to the organic solvents. The stoichiometry and the formation constants of the α-cypermethrin inclusion complexes formed with the CDs were determined. The analytical performances of the PIF method were improved in the presence of HP-β-CD relative to the other media, and a CD-enhanced PIF analytical method was developed. The limits of detection and limits of quantification ranged, respectively, between 6 and 98 ng/mL and between 24 and 343 ng/mL, depending on the medium. Application to the analysis of tap water and Senegal natural water samples collected close to agricultural areas and spiked with α-cypermethrin yielded satisfactory recoveries going from about 77% to 98%. An interference study of foreign species, including pesticides and inorganic ions likely to be present in natural waters, was also carried out. Figure Photolysis reaction of α-cypermethrin in presence of HP-β-CD
Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes
Background Schistosomes are dioecious parasitic flatworms, which live in the vasculature of their mammalian definitive hosts. They are the causative agent of schistosomiasis, a disease of considerable medical and veterinary importance in tropical and subtropical regions. Schistosomes undergo a sexual reproductive stage within their mammalian host enabling interactions between different species, which may result in hybridization if the species involved are phylogenetically close. In Senegal, three closely related species in the Schistosoma haematobium group are endemic: S. haematobium, which causes urogenital schistosomiasis in humans, and S. bovis and S. curassoni, which cause intestinal schistosomiasis in cows, sheep and goats. Methodology/Principal Findings Large-scale multi-loci molecular analysis of parasite samples collected from children and domestic livestock across Senegal revealed that interactions and hybridization were taking place between all three species. Evidence of hybridization between S. haematobium/S. curassoni and S. haematobium/S. bovis was commonly found in children from across Senegal, with 88% of the children surveyed in areas of suspected species overlap excreting hybrid miracidia. No S. haematobium worms or hybrids thereof were found in ruminants, although S. bovis and S. curassoni hybrid worms were found in cows. Complementary experimental mixed species infections in laboratory rodents confirmed that males and females of each species readily pair and produce viable hybrid offspring. Conclusions/Significance These data provide indisputable evidence for: the high occurrence of bidirectional hybridization between these Schistosoma species; the first conclusive evidence for the natural hybridisation between S. haematobium and S. curassoni; and demonstrate that the transmission of the different species and their hybrids appears focal. Hybridization between schistosomes has been known to influence the disease epidemiology and enhance phenotypic characteristics affecting transmission, morbidity and drug sensitivity. Therefore, understanding and monitoring such inter-species interactions will be essential for optimizing and evaluating control strategies across such potential hybrid zones.
The Lancet Nigeria Commission: investing in health and the future of the nation
Effective, quality reproductive, maternal, and child health services including family planning, and female education and empowerment are likely to accelerate demographic transition and yield a demographic dividend. Nigeria's lower life expectancy is partially due to having more deaths in children of 5 years and younger than any other country in the world, including more populous India and China and countries experiencing widespread long-term conflict, such as Somalia. Interventions are needed to improve child nutrition, reduce indoor and outdoor air pollution, address unmet family planning needs, and improve access to safe drinking water and sanitation. Nigeria needs better manufacturing capacity for essential health products, medicines and vaccines, the provision of diagnostics, surveillance and preventive public health measures in health facilities and community settings, as well as other preventive and curative measures.