Rapidly rising cases with Omicron in Senegal.

•Omicron variant continues to progress in Senegal with the appearance of new contaminations.•IRESSEF detected the first positive case of the Omicron variant on Friday, December 3, 2021.•Since this date, the number of Omicron variant infections has increased over the weeks.•Molecular surveillance of the Omicron variant is carried out in real time to inform the medical authorities.

Demographics and outcomes of laboratory-confirmed COVID-19 cases during the first epidemic wave in Senegal.

BACKGROUND: Few studies have focused on the effects of COVID-19 on African populations. During the first epidemic wave in Senegal (May 1 to July 31, 2020), COVID-19 cases were isolated in treatment centers of epidemics (TCEs). We described the demographics and outcomes of COVID-19 cases in TCEs. PATIENTS AND METHODS: All cases with laboratory-confirmed COVID-19 in Thiès medical region of Senegal were included. RESULTS: COVID-19 was confirmed in 600 cases. Median age of cases (men: 357, 59.5%; women: 243, 40.5%) was 34.0years. The incidence was 12 per 100,000 inhabitants per month. Overall, 46 (7.7%) cases had a severe or critical form of the disease, and nine of them died. Of 455 cases quarantined in non-hospital TCEs, 340 (74.7%) had no symptom and 115 (25.3%) had mild or moderate symptoms. CONCLUSION: In this African retrospective cohort, COVID-19 cases were young and mostly asymptomatic with a low case fatality rate.

Development of a new automatic on-site detector of pesticides in natural waters by photo induced fluorescence, application to three phenylurea and benzoylurea herbicide.

Prototypes of on-site automatic photo induced fluorescence detectors of pesticide in natural waters are set up and applied for the determination of the benzoyl- and phenylurea pesticides, namely fluometuron, monolinuron and diflubenzuron. As these pesticides present no native fluorescence the set up system use the photo conversion under UV irradiation of these pesticides into highly fluorescent photoproducts. A first system, called AUTOPIF, (evolution the commercial AQUAPOD system) is develop using a detection via a diode array spectrometer. To improve the sensitivity of the method, a second system, called AUTOPIF+, is developed with a more resolute spectrometer and an intensified CCD camera detection. Analytical applications were carried out in aqueous solution and detected on line with the AUTOPIF and AUTOPIF+ system. The calibration curves are linear over one order of magnitude, and the limits of detection are in the µg mL-1 range. The analytical performances of these methods for the determination of the three pesticides are satisfactory in comparison to other classical PIF methods published for the determination of phenylurea pesticides in aqueous solutions. Our results show that the AUTOPIF and AUTOPIF+ methods are versatile, sensible and can be easily applied as an alert system to detect pollutant residues in naturals waters over a threshold value.

Photochemically-induced fluorescence properties of two benzoyl- and phenylurea pesticides and determination in natural waters.

A photo-induced fluorescence (PIF) method was developed for the determination of two benzoyl- and phenylurea pesticides, namely diflubenzuron (DFB) and fenuron (FEN). The photoconversion under UV irradiation of both pesticides into strongly fluorescent photoproducts was performed in several media (methanol, ethanol, acetonitrile, pH4 aqueous solution and pH4 water-methanol (30:70, v/v) mixture). PIF parameters were optimized. Analytical figures of merit for the PIF determination of DFB and FEN were satisfactory, with rather wide linear dynamic range (LDR) values of one to two orders of magnitude, relatively low limit of detection (LOD) values of, respectively, 9-24 ng/mL for DFB and 1-28 ng/mL for FEN, and limit of quantification (LOQ) values of, respectively, 30-80 ng/mL for DFB and 4-95 ng/mL for FEN, according to the medium. Relative standard deviation (RSD) values were in the range 1.7-5.6%. PIF was validated by comparing its analytical performances to those of a standard UV absorption spectrophotometric method. The optimized PIF method was applied to the quantitative analysis of both pesticides in various spiked natural water samples collected in a Senegal agricultural area by the standard addition procedure prior to extraction steps in dichloromethane, with satisfactory mean recovery percentage values (97.0-105.3 for DFB and 98.3-102.8% for FEN). An interference study of foreign species, including pesticides and inorganic ions, likely to be present in natural waters, was also carried out.

Determination of phenylurea pesticides by direct laser photo-induced fluorescence.

A direct Laser Photo-Induced Fluorescence (DL-PIF) method is developed for the determination of two phenylurea pesticides, namely fenuron and diflubenzuron. The DL-PIF method uses a tunable Nd:YAG-OPO Laser to obtain the photoproduct(s) and to simultaneously analyse their fluorescence in a short acquisition time on an intensified CCD camera. Compared to classical PIF methods, the use of a tunable laser improves the selectivity (by choosing the suitable excitation wavelength), increases the sensitivity (due to the high energy of the beam) and also reduces the time of analysis. The analytical performances of this method for the determination of both pesticides are satisfactory in comparison to other classical PIF methods published for the determination of phenylurea pesticides. The calibration curves were linear over one order of magnitude and the limits of detection were in the ng mL(-1) range. Satisfactory recoveries were obtained in the analysis of both pesticides in river and sea water spiked samples.

[Decentralization of the immunological monitoring of people living with HIV/AIDS in a limiting setting with a low HIV seroprevalence: the experience of Senegal]. / Décentralisation du suivi immunologique des personnes vivant avec le VIH dans un pays à ressources limitées et à prévalence faible: expérience du Sénégal.

Our work aimed to propose a manual method of counting CD4 T lymphocytes which is an alternative magnetic immunoseparation followed by a reading with a fluorescence microscope as an alternative to the automated flow cytometry. This alternative technique is easier for use, less expensive and could answer the difficulties encountered for the monitoring CD4 T cells count in developing countries. The specific objectives were: 1) to train the technicians of the peripheral sites in order to make the numeration of the CD4 T lymphocytes more accessible at the peripheral level; 2) to equip the sites with necessary facilities for the T lymphocytes CD4 count; 3) to put in place a system of quality control permitting the reliability of the results. A hundred and fifty patients have been enrolled in three care services for people living with HIV/AIDS in Dakar. This population was constituted of 119 seropositive and 31 seronegative patients acting as control group to have some patients with high rates of T lymphocytes CD4. For the follow-up at peripheral level, the patients were constituted of the active line of the patients living with HIV/AIDS supported in the targeted sites. The measurements allowed studying concordances for different rates of lymphocytes: 0 to 199, 200 to 499 and over 500 cells by mm3. The results showed also a very good correlation (r = 0.97 or r = 0.98 according to the operator) between the two methods for CD4 rates inferior to 500 cells by mm3 among both the negative group and the HIV positive patients. We also discussed the profit of decentralization for the program and the patient, as well as the setting up of an external quality control to validate the alternative technique. According to the results, the Dynabeads is well correlated with the Facscount. It is a technique that can be used as an alternative in the zones with limited resources, low prevalence and for a small number of samples.