Highly efficient and sensitive membrane-based concentration process allows quantification, surveillance, and sequencing of viruses in large volumes of wastewater.

Wastewater-based epidemiology is experiencing exponential development. Despite undeniable advantages compared to patient-centered approaches (cost, anonymity, survey of large populations without bias, detection of asymptomatic infected peoples…), major technical limitations persist. Among them is the low sensitivity of the current methods used for quantifying and sequencing viral genomes from wastewater. In situations of low viral circulation, during initial stages of viral emergences, or in areas experiencing heavy rains, the extremely low concentrations of viruses in wastewater may fall below the limit of detection of the current methods. The availability during crisis and the cost of the commercial kits, as well as the requirement of expensive materials such as high-speed centrifuge, can also present major blocks to the development of wastewater-based epidemiological survey, specifically in low-income countries. Thereby, highly sensitive, low cost and standardized methods are still needed, to increase the predictability of the viral emergences, to survey low-circulating viruses and to make the results from different labs comparable. Here, we outline and characterize new protocols for concentrating and quantifying SARS-CoV-2 from large volumes (500 mL-1 L) of untreated wastewater. In addition, we report that the methods are applicable for monitoring and sequencing. Our nucleic acid extraction technique (the routine C: 5 mL method) does not require sophisticated equipment such as automatons and is not reliant on commercial kits, making it readily available to a broader range of laboratories for routine epidemiological survey. Furthermore, we demonstrate the efficiency, the repeatability, and the high sensitivity of a new membrane-based concentration method (MBC: 500 mL method) for enveloped (SARS-CoV-2) and non-enveloped (F-specific RNA phages of genogroup II / FRNAPH GGII) viruses. We show that the MBC method allows the quantification and the monitoring of viruses in wastewater with a significantly improved sensitivity compared to the routine C method. In contexts of low viral circulation, we report quantifications of SARS-CoV-2 in wastewater at concentrations as low as 40 genome copies per liter. In highly diluted samples collected in wastewater treatment plants of French Guiana, we confirmed the accuracy of the MBC method compared to the estimations done with the routine C method. Finally, we demonstrate that both the routine C method processing 5 mL and the MBC method processing 500 mL of untreated wastewater are both compatible with SARS-CoV-2 sequencing. We show that the quality of the sequence is correlated with the concentration of the extracted viral genome. Of note, the quality of the sequences obtained with some MBC processed wastewater was improved by dilutions or enzyme substitutions suggesting the presence of specific enzyme inhibitors in some wastewater. To the best of our knowledge, our MBC method is one of the first efficient, sensitive, and repeatable method characterized for SARS-CoV-2 quantification and sequencing from large volumes of wastewater.

Evaluation of retinal nerve fiber layer thickness measured by optical coherence tomography in Moroccan patients with multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by focal inflammatory infiltrates, demyelinating lesions and axonal injury. The purpose of the study was to evaluate the retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) in Moroccan patients with MS and to assess the relationship between RNFL thickness and disease duration, Expanded Disability Status Scale (EDSS) score, visual acuity and automated visual field indices. MATERIALS AND METHODS: Thirty-one patients with definite MS and thirty-one disease-free controls were enrolled in the study. After neurologic consultation, ophthalmologic examination including visual acuity, automated visual field testing and OCT were performed. RESULTS: Significant differences between both groups were observed in OCT parameters (total, temporal and macular ganglion cell layer) with lower thickness in the MS group. In patients without a history of optic neuritis, there were statistically significant inverse correlations between total RNFL thickness and disease duration, neurologic disability evaluated by the EDSS, logMAR visual acuity and automated visual field indices. CONCLUSIONS: OCT seems to be a reproducible test to detect axonal loss of ganglion cells in MS. Further and larger longitudinal prospective studies would be valuable to assess the evolution over time of the RNFL measurements in Moroccan MS patients.

[Bilateral stellate neuroretinitis as presenting sign of pheochromocytoma]. / Neurorétinite stellaire bilatérale révélant un phéochromocytome.

We report the case of a 21-year-old male patient admitted emergently with progressive bilateral severe visual loss for 1 month. Posterior segment examination revealed bilateral stellate neuroretinitis. Infectious serologies were negative, and brain CT was normal. Physical examination was remarkable for malignant hypertension of 220/150 mmHg. Diagnostic work-up revealed a pheochromocytoma documented by histopathological exam upon adrenalectomy. The disc edema and macular exudates resolved once the hypertension was controlled.

[Risk factors for failure of scleral buckling in rhegmatogenous retinal detachment. A Moroccan series]. / Facteurs d'échec de la chirurgie épisclérale dans le décollement de rétine rhegmatogène. À propos d'une série marocaine.

PURPOSE: To evaluate risk factors for failure of scleral buckling in rhegmatogenous retinal detachment (RRD) in an adult Moroccan population. METHODS: A retrospective study of 432 eyes of 422 patients undergoing scleral buckling (SB) for primary RRD between 2001 and 2009 was carried out. Statistical analysis of risk factors for failure was performed using binary logistic regression. RESULTS: Mean patient age was 43 ± 15 years, and 45.4% were myopic. The median recurrence was at 10 months. The final failure rate was 22.5%. Univariate analysis shows that significant risk factors for failure were extent of RRD ≥ 3 quadrants (P<0.001), advanced PVR (P<0.001) and worsening PVR postoperatively (P<0.001). In the multivariate model, the only significant risk factor for failure was the worsening postoperative PVR (P<0.001). CONCLUSIONS: Our findings suggest that worsening of PVR after surgery is the major risk factor for failure of SB in RRD. Thus, it is necessary to recognize the risk factors contributing to PVR and to plan the most appropriate, earliest and least traumatic surgical treatment of RRD.

[Retrobulbar optic neuropathy secondary to an undifferentiated carcinoma of the sphenoid sinus]. / Neuropathie optique rétrobulbaire révélant un carcinome indifférencié du sinus sphénoïdal.

Undifferentiated carcinoma of the paranasal sinuses is a rare malignant tumor, characterized by rapid growth, local/regional invasion, metastatic potential and poor prognosis despite aggressive treatment. Clinically, this tumor may manifest as episodes of epistaxis, headache or ophthalmic signs, particularly oculomotor nerve palsies, optic atrophy or even proptosis in the case of orbital extension. We report the case of a patient admitted with a left retrobulbar optic neuropathy, which led to a diagnosis of undifferentiated carcinoma of the sphenoid sinus.