Detection of Pathogenic Human Adenoviruses and Enteroviruses in Water Samples Collected from Lake Victoria along Homa Bay Town, Homa Bay County, Kenya

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. 1 CHAPTER ONE INTRODUCTION 1.1 Background information Lake Victoria (LV), the second largest fresh water lake in the world is a source of livelihood for many people around the Eastern part of Africa. Over 20 million people depend on it for very many uses including drinking, recreational and industrial activities (Odada et al., 2004). The lake‟s catchment area is one of the most densely populated regions in Africa and the lake is economically significant to this population (Kessides, 2006). The most important economic activities at the lake includes but not limited to water transport and fishing activities. Over the last five decades, LV ecosystem and the water quality in general has been deteriorating (Odada et al., 2004). The deterioration of the ecosystem and the water quality are as results of eutrophication, invasive species and acidification all of which can be associated to human impacts as a result of increase in population (Odada et al., 2004). Populace development and the exercises required to support the expanding populace has led to expanded inflows of pollutants and supplements to the lake and waterways from the catchment leading to contamination of the lake and water-related general medical issues especially in low socio-economic activity areas such as Homa-Bay region (Obudho, 1995). Every day thousands of litres of crude sewage and refuse stream into the lake from households and enterprises found in many towns around the lake. Untreated sewage from Homa Bay town sewage treatment system for example was discharged into the lake directly since the treatment plant was out of order. 2 The increased fecal pollution of the nearshore lake waters might be related to the increased instances of water-borne illnesses and other water related medical conditions and maladies. These may include looseness of the bowels, intestinal worms, cholera, typhoid, diarrhoea and the enteric viruses‟ related cases (Otula, 2005). The volume of neighbourhood sewage discharge and urban overflow to the lake has transformed into an important general public health stress in the area. Increased contamination of the lake is debilitating its sustainable utilization, an imperative resource asset for Kenya, Uganda and Tanzania (Otula, 2005). Developing interest in global markets for fresh water fish species such as Nile Perch (Lates niloticus) and Tilapia (Oreochromis niloticus) from this lake has prompted the increase in the number of fishermen into the lake. Many fishing water crafts are out on the lake every night to supply Capital fish processing industry in the town with the raw materials. The large number of fishermen equally increases the chances of contamination by different species of microorganisms including enteric viruses as a result of improper disposal of human waste products (WHO/UNICEF, 2014). Poor management of microbial contamination of aquatic environments presents a potential general public health hazard (Otula, 2005). Surveillance of most waterborne diseases worldwide shows that of the many cases recorded for untreated surrounding water, 28.7 % are of an obscure etiology and are responsible for intense gastroenteritis (Sinclair et al., 2009). In recreational epidemiological studies, diarrhoea and respiratory ailments are the most common reported health outcomes (Colford et al., 2007), with a belief that there is a relationship between these ailments and different enteric viruses