No abstract

Microbiological water quality of the Mfoundi River watershed at Yaoundé, Cameroon, as inferred from indicator bacteria of fecal contamination Djuikom, E.; Njine, T.; Nola, M.; Sikati, V.; Jugnia, L.-B. Abstract. Using the membrane filtration technique to count total coliform (TC), fecal coliform (FC) and fecal streptococci (FS), the microbiological water quality of the Mfoundi River and four of its representative tributaries at Yaoundé, Cameroon, was assessed for human use and contact. Sampling was conducted so as to examine the potential origin of fecal contamination and how rainfall affects the measured concentrations of indicators organisms. Our results revealed that waters were not safe for human use or primary contact according to the standards for water quality established by the Word Health Organization (WHO). Indeed, these waters exhibited high concentrations of TC (Mean ± SD = 5.6 × 10 8 ± 2.5 × 10 6 CFU/100 ml), FC (Mean ± SD = 6.8 × 10 5 ± 2.4 × 10 3 CFU/100 ml) and FS (Mean ± SD = 7.3 × 10 5 ± 2.1 × 10 3 CFU/100 ml) that varied with the sampling sites and points. FC/FS ratio suggested that this contamination was more from warm-blooded animals than humans and correlation analysis points to the role of rainfall as a contributing factor, which enhanced the bacterial numbers detected. We conclude that there is a great potential risk of infection for users of waters from the Mfoundi River and its tributaries at Yaoundé.

Une étude bactériologique a été menée sur 588 échantillons d'eau prélevés dans 49 puits de 7 quartiers de la ville de Douala. Les quartiers ont été choisis suivant la typologie de l'habitat. Les analyses des coliformes ont été faites suivant la technique par inclusion en une couche, et celle des streptocoques par ensemencement dans les tubes à vis avec bouillon de Rothe. Les résultats montrent que ces eaux abritent de nombreuses bactéries pathogènes, coliformes fécaux et streptocoques fécaux. Leurs densités subissent d'importantes fluctuations spatiales et temporelles, et varient entre 200 et 29*10 5 UFC/100 ml pour les coliformes totaux et entre 30 et 44*10 3 UFC/100 ml pour les coliformes fécaux ; les streptocoques fécaux sont le plus souvent présents. Les facteurs de variation sont l'environnement du puits, l'entretien, le niveau de la nappe dans le puits, la situation géographique. Les puits les plus contaminés sont ceux qui sont situés à moins de 5 m des sources de pollution telles que les latrines à fond perdu, les dépôts sauvages des ordures ménagères, l'absence ou le traitement régulier de l'eau, le niveau superficiel de l'eau dans le puits. Les puits aménagés, c' est-à-dire munis d'un couvercle bien utilisé et d'une margelle en béton, avec une profondeur d'au moins 4 m, situés au moins à 15 m en amont d'une quelconque source de pollution et dont le traitement est régulier, présentent tous une eau de qualité beaucoup améliorée ; les contaminations fécales y baissent d'au moins 1000 unités. Les points d'eau non aménagés sont très nombreux et les fortes densités de germes dans ces eaux montrent de grands risques sanitaires à court terme pour les consommateurs.

Significance and suitability of Aeromonas hydrophila vs. fecal califorms in assessing microbiological water quality Djuikom, E.; Njiné, T.; Nola, M.; Kemka, N.; Zébazé Togouet, S. H.; Jugnia, Louis-B. ORIGINAL PAPERSignificance and suitability of Aeromonas hydrophila vs. fecal coliforms in assessing microbiological water quality E. Djuikom AE T. Njiné AE M. Nola AE N. Kemka AE S. H. Zébazé Togouet AE Louis-B. Jugnia Abstract We examined the significance and suitability of Aeromonas hydrophila versus fecal coliforms in assessing microbiological water quality. For this, we used the membrane filtration method to simultaneously estimate the abundance level of A. hydrophila and fecal coliforms in waters from the Mfoundi river watershed at Yaoundé, and compared how fluctuations in A. hydrophila abundance matched those observed with fecal coliforms index as an indicator of water quality in the system under study. Our results revealed that waters were not safe according to the standards for water quality established by the Word Health Organization (WHO). They also indicated the prevalence of A. hydrophila as compared to fecal coliforms, and suggested that water from the Mfoundi River and its tributaries could be classified as hypereutrophic based on the density of Aeromonas. Moreover, the spatial distribution of fecal coliforms and A. hydrophila exhibited similar trends within the different water bodies investigated, suggesting that A. hydrophila can be used as indicator of water quality in highly polluted waters. We concluded that waters from the Mfoundi River watershed at Yaoundé represent a great potential risk of infection for users, and foresee that the next challenge will be to determine, among other factors, the physico-chemical factors influencing the observed spatial distribution.

Water quality of the Mfoundi River and four of its tributaries was studied by assessing some physicochemical variables (temperature, pH, conductivity, chlorides, phosphates and nitrogen ammonia, dissolved oxygen and carbon dioxide, organic matter content and Biological Oxygen Demand) and their influence on the distribution of bacterial indicators of faecal contamination (total coliform, faecal coliform and faecal streptococci). For this, standard methods for the examination of physicochemical parameters in water were followed, and statistical analysis (Pearson correlations) used to establish any relationships between physicochemical and biological variables. Our results revealed that almost all of the examined physicochemical variables exceeded World Health Organization (WHO) guidelines for recreational water. This was in agreement with a previous microbiological study indicating that these waters were not safe for human use or primary contact according to water quality standards established by the WHO. Results of our correlation analysis suggested that physicochemical and biological variables interact in complicated ways reflecting the complex processes occurring in the natural environment. It was also concluded that pollution in the Mfoundi River watershed poses an increased risk of infection for users and there exists an urgent need to control dumping of wastewater into this watershed.