Virological and Bacteriological Quality of Selected Drinking Water Samples Referred to Ethiopian Public Health Institiute
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Date
2016-10
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Addis Ababa University
Abstract
Background: Water Quality monitoring is assessed widely using different indicators.
Since there is no universal indicator that has been identified yet, assessing water quality
using bacterial and viral indicators that would provide a more complete picture of water
quality.
Objective: To assess the quality of drinking water using bacterial and cophages indicators.
Methodology: A cross sectional prospective study was conducted on 218 drinking water
samples of various sources collected from some regions of Ethiopia from February to June
2016 to determine coliphages by the help of CB390 E. coli host using plaque assay
technique; most probable number for coliforms and pouring for hetrotrophic plate count at
Ethiopian Public Health Institute. The data was analyzed using SPSS 20 statistical package.
Results: Hetrophilic bacteria, total and thermotolerant coliforms, E. coli and coliphages
were detected in 72.9 %, 51.8%, 38.5%, 23.9% and 2.3 % of total water samples
respectively. HPC > 1.0x102 Cfu/ml were noted in 41 (18.8%) water samples and
detections of total coliforms, thermotolerant coliforms and E. coli in 38 (17.4%), 24
(11.0%) and 10 (4.6%) samples respectively and no detection of phages in chlorinated
waters. While, HPC > 1.0x102 Cfu/ml were observed in 100 (45.9%) water samples and
detections of total and thermotolerant coliforms, E.coli and coliphages in 75 (34.4%), 60
(27.5%), 42 (19.3% ) and 5 (2.3%) samples respectively for the untreated waters. Rho
values between total coliphages and other indicators, HPC, total coliforms, thermotolerant
coliforms were 0.202, 0.232 and 0.269 respectively. Total heterophilic plate count, total
coliforms, thermotolerant coliforms, E.coli and total coliphages were statistically differed
by region; sources and treatment type (P value < 0.05). Coliphages were not detected in all
waters except rivers.
Conclusion: Majority of the waters, mainly untreated sources contained bacterial and viral
indicators above the standard limits. This indicates that the sources are contaminated with
environmental and fecal contaminants signifying poor quality of water and it is a potential
threat for human health. Hence regular monitoring of water source using coliphages and
other bacterial indicators should be a priority agenda by all stake holders.
Keywords: Indicators, drinking water, water sources, coliforms, coliphage
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Keywords
Indicators, Drinking water, Water sources, Coliforms