This study focusses on the geological formations of the Alfallé massif located approximately 75km east of the town of N'Goura, in the Hadjer-Lamis Province of Chad (13°N, 17°E), and their ability to provide good quality aggregates in an area with poor hard rock ressources. We investigated the petrographic and mechanical characteristics of these formations in a resource perspective. The massif is made up of three lithologies: alkali feldspar megacrystalline granite, biotite-rich fine grained quartz monzonite and biotite-rich fine grained gneiss. Alkali feldspar megacrystalline granite is composed of quartz (30%), orthoclase (30%), plagioclase (20%), biotite (15%) and opaque minerals (≈5%). Micro-monzonite is composed of quartz (15-20%), orthoclase (20-25%), plagioclase (18-25%), biotite (20-25%) and opaque minerals (≈4%). The biotite gneiss is composed of quartz (25-30%), alkali feldspars (25-27%), plagioclase (17%), biotite (25-27%) and opaque minerals (≈5%). The mechanical characteristics of the aggregates show that the aggregates studied have specific density values of between 2.58 and 2.75g/cm3 with an average value of 2.66g/cm3, a Los-Angeles coefficient of 11.2% to 28.9% with an average value of 20.1% and a wet Micro-Deval coefficient of 5.2% to 10.8% with an average value of 7.6%. The values obtained indicate that the materials studied have excellent to satisfactory properties, and that Alfallé massif provide the best characteristics among six different quarrying area in Central Chad. We propose that such rare residual reliefs within the mega-Chad paleolake area reach optimal mechanical properties through a natural selection process, specific of the paleolake erosional conditions.

The assessment of water quality consists of counting bacteria indicating fecal contamination or detecting the presence of pathogenic bacteria using standardized or validated methods of classical microbiology. Our present study aims to determine the bacteriological quality of drilling water in the Tandjilé region of Chad. Our method used was based on qualitative and quantitative research on suspected total coliforms, Echerichia Coli and fecal enterococci were analyzed according to the standard routine methods of the French Association for Normalization (AFNOR). Microbiological analysis shows the presence of indicators of fecal contamination such as total coliforms, Escherichia coli and fecal enterococci. The number of strains detected in 100 ml were E. coli (7 /29 samples), fecal Streptococcus (6 /29 samples) and total coliforms (29/29 samples), respectively from borehole water. The contamination rate of E. coli is 24.13%, total coliforms 100% and 20.68% of fecal enterococci in boreholes. The high number of these microorganisms is more than the values recommended by the WHO for the quality of drinking water. Corrective and urgent measures are needed to improve the quality of these water resources, rich in pathogens, which are health risks, and the causes of infectious diseases such as gastroenteritis, diarrhea, typhoid and skin diseases.

Water resources are threatened nowadays by pollution that comes from domestic, industrial and agricultural discharges without prior treatment. This pollution causes the degradation of water quality. Surface pollutants can seep through the soil into water tables. The objective of our work is to assess and control the physicochemical quality of the Chari Baguirmi groundwater, to protect human health. The quality of 83 boreholes was assessed, while performing analysis for 12 physicochemical parameters at the National Water Laboratory and at the Center for Quality Control of Foodstuffs in Chad. These parameters are: pH, EC, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NH4+ and NO3- , Fe2+ and HCO3-. Also, the results obtained were compared with WHO standards. The geochemical statistical approach has made it possible to characterize the hydro geochemical properties and to understand the major processes of the mineralization of groundwater resources in Chari Baguirmi region in Chad. Some of its waters are acidic and weakly mineralized, rich in Fe2+ and NH4+. The origin of the mineralization is due to the alteration of the host rocks and to the hydrolysis of silicate and ferromagnesian minerals as well as anthropogenic pollution. The ammonium concentrations in N’Djamena boreholes are higher than WHO standards, indicating the presence of pollution which may come from organic waste. These results constitute a preliminary step in understanding hydro geochemical functioning and a basis for monitoring the physicochemical quality of the water in the study area.

Introduction: Nephrotic syndrome (NS) remains the most frequent mode of presentation of glo-merular diseases in children; in addition, the NS is primitive, i.e., idiopathic in 90% of cases with an average age of onset between 2 and 10 years. The objective of our study was to describe the char-acteristics and outcome of NS in children from 3 major hospitals from one of the poorest countries worldwide (Chad). Patients and Methods: Observational, cross-sectional, descriptive and multicenter study which took place over a period of 36 months (January 1,2019-December 31,2021) carried out in 3 hospitals in N’Djamena (Chad). All children aged 1-15 years presenting with NS were included. Results: Out of 16,776 children hospitalized or followed-up in outpatient clinics, 24 cases of NS were identified, giving a prevalence of 0.14%. The median age at presentation was 6.16(1-10) years. Nineteen children were male (sex ratio 3.8). There were 8 impure NS (33.3%). Edema was present in all patients, oliguria in 29.16%(n=7), and arterial hypertension in 20.83%(n=5) of cases. Mean proteinuria, albuminemia and total proteins were 2.86g/L, 19.13g/L and 30.41g/L respectively. Median serum creatinine was 87.3 µmol/L(75-1375µmol/L); three patients had acute renal failure on admission. Four patients had secondary NS. All patients (n=20) with idiopathic NS had received corticosteroid therapy; steroid-sensitivity was found in 90% of patients. Those who were not ster-oid-sensitive or relapsed underwent kidney biopsy (n=7); the most represented histological lesion was focal segmental glomerulosclerosis (FSGS; n=4), followed by minimal change disease (n=2), and membranoproliferative glomerulonephritis (n=1). The median length of hospitalization stay was 10.67 (5-27) days. None of the patients with idiopathic NS died. At last follow-up sixteen patients (80%) achieved long-term complete remission with normal renal function; however, 4 had subse-quent relapses. 16 patients. One patient with secondary NS died. Conclusion: In Chad childhood idiopathic nephrotic syndrome involves mostly young male; steroid sensitivity is as high as 95% and in the long-term 80% of the patients are in remission with normal renal function.