Detection of Pathogenic Human Adenoviruses and Enteroviruses in Water Samples Collected from Lake Victoria along Homa Bay Town, Homa Bay County, Kenya
Wasonga, Michael Opere
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Lake Victoria is the main source of water in Homa Bay town as well as the surrounding community. Increase in population in the resent past has led to intensified human activities with a possible compromise on the sanitation standards around the town consequently resulting into increased fecal load to the lake through fecal pollution. Increased fecal contamination of the lake has consequently led to an increase in pathogenic microorganisms including waterborne enteric viruses. These viruses can affect both human and animals health by causing diseases such as gastrointestinal infections. Research on viral water quality in Lake Victoria is limited. The objectives of this study were to determine the occurrence of these pathogenic enteric viruses with respect to human adenoviruses and enteroviruses in Lake Victoria Waters. Factors that may have influenced the levels of contamination of the lake water by the viruses such as physical water parameters, seasonal variations, proximity to sewage effluent and pit latrines were assessed. Water samples were collected from six sites commonly used for domestic and commercial purposes spanning approximately 3 km along the shoreline for analysis for the presence or absence of the two groups of enteric viruses over a seven month period. A total of 216 water samples were analysed for possible contamination with the viruses using nested PCR method. Paired t test, ANOVA, Odds Ratios, Correlation and Regression analysis (STATA ver.13.0) were performed to determine factors associated with the virus contamination of the waters. P-values<0.05 were considered significant at 95 % confidence interval. Analysis showed that the lake is contaminated with adenoviruses and enteroviruses which were discovered in 11(5.09 %) and 7(3.24 %) of the samples, respectively. The presence of the enteric viruses was strongly associated with the distance from possible sources of contamination (odds ratio 20.28 and 4.86, confidence interval 2.42, and 0.95) for pit latrines and the sewage treatment plant respectively. Neither wet season nor dry season was associated with the prevalence of the viruses. Of the 72 samples collected from the sites (L5 and L6) closer to the sewage effluent points 13(18 %) tested positive for the two types of viruses. This research clearly signifies that waste water discharge and wastewater-impacted surface waters along the shores of Lake Victoria contain some enteric viruses. This contamination may be due to the fact that the enteric viruses can highly persist in the environmental waters due to their ability to be resistant to environmental conditions. This viral analysis will provide the much needed information in controlling the source of pollution of the lake, such as untreated sewage effluents. It will be useful in ascertaining health risks from the analysis of viral exposure. Further research and analysis is recommended to ascertain the true position concerning the public heath implication and whether the contamination may be as a result of ineffective waste water treatment.