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BackgroundOcular toxoplasmosis is common across all regions of the world. Understanding of the epidemiology and approach to diagnosis and treatment have evolved recently. In November 2020, an international group of uveitis-specialised ophthalmologists formed the International Ocular Toxoplasmosis Study Group to define current practice.Methods192 Study Group members from 48 countries completed a 36-item survey on clinical features, use of investigations, indications for treatment, systemic and intravitreal treatment with antiparasitic drugs and corticosteroids, and approach to follow-up and preventive therapy.ResultsFor 77.1% of members, unilateral retinochoroiditis adjacent to a pigmented scar accounted for over 60% of presentations, but diverse atypical presentations were also reported. Common complications included persistent vitreous opacities, epiretinal membrane, cataract, and ocular hypertension or glaucoma. Most members used clinical examination with (56.8%) or without (35.9%) serology to diagnose typical disease but relied on intraocular fluid testing—usually PCR—in atypical cases (68.8%). 66.1% of members treated all non-pregnant patients, while 33.9% treated selected patients. Oral trimethoprim–sulfamethoxazole was first-line therapy for 66.7% of members, and 60.9% had experience using intravitreal clindamycin. Corticosteroid drugs were administered systemically by 97.4%; 24.7% also injected corticosteroid intravitreally, almost always in combination with an antimicrobial drug (72.3%). The majority of members followed up all (60.4%) or selected (35.9%) patients after resolution of acute disease, and prophylaxis against recurrence with trimethoprim–sulfamethoxazole was prescribed to selected patients by 69.8%.ConclusionOur report presents a current management approach for ocular toxoplasmosis, as practised by a large international group of uveitis-specialised ophthalmologists.

Understanding the geochemical behavior of uranium (U) in the environment is crucial for the limitation of U dissemination in contaminated systems. The primary objective of this thesis was to determine the potential evolution of noncrystalline U phases over thousand years in naturally U-rich lacustrine sediments (up to more than 1000 µg/g) from Lake Nègre, in the Mercantour-Argentera Massif (South-East France). Using U isotopic ratios (δ238U and (234U/238U)) and U L3-edge X-ray absorption spectroscopy (XAS), we show that U is first deposited as organic-bound mononuclear species and is readily reduced to U(IV). In less than 700 years, these species transform into U(IV)-silica polymers with a local structure close to that of coffinite (USiO4·nH2O). This transformation highlights the role of ligand abundance in limiting the precipitation of crystalline U phases, but only slightly reduces the lability of uranium which potential mobility remains significant even after several thousand years. At the watershed scale, U originates from fractures in the granitic bedrock and is subsequently scavenged in the soils, especially in the wetland upstream of the lake (up to > 5000 µg/g), before being transported through erosion. Uranium scavenging in the soils occurs through complexation by organic matter including particular biological structures, followed by partial reduction to U(IV). U is thus mainly present in mononuclear species but also in polymeric U(VI) phases which may potentially result from U aging after thousand years of accumulation.; La connaissance du comportement géochimique de l’uranium (U) dans l’environnement est essentielle pour en limiter la propagation dans les milieux contaminés. Ce travail de thèse visait avant tout à déterminer l’évolution sur plusieurs milliers d’années des phases non-cristallines de U dans les sédiments naturellement riches en U (jusqu’à plus de 1000 µg/g) du lac Nègre, dans le massif du Mercantour (Alpes-Maritimes, France). Grâce aux rapports isotopiques de U (δ238U et (234U/238U)) et à la spectroscopie d’absorption X (XAS) au seuil L3 de U, il est montré que U est déposé initialement sous forme d’espèces mononucléaires liées à la matière organique, et est rapidement réduit en U(IV). En moins de 700 ans, ces phases sont transformées en polymères de U(IV)-silice avec une structure locale proche de la coffinite (USiO4·nH2O). Cette transformation souligne l’impact de l’abondance de ligands qui limitent la précipitation de phases cristallines de U, mais ne réduit que faiblement la labilité de U, dont la mobilité potentielle reste importante après plus de 3000 ans. A l’échelle du bassin versant, U provient initialement de fractures dans la roche-mère granitique, puis est piégé en grandes quantités dans les sols, en particulier dans la zone humide en amont du lac (jusqu’à > 5000 µg/g U), avant d’être transporté vers le lac par érosion. Cette fixation dans les sols a lieu par complexation sur la matière organique dont certaines structures biologiques, avant réduction partielle en U(IV). On trouve ainsi surtout des formes mononucléaires de U, mais aussi des phases polymériques de U(VI) potentiellement issues d’un vieillissement de U après des milliers d’années d’accumulation.