RISK ASSESSMENT OF FAECAL CONTAMINATION IN RIVER OWENA AND PROBABILITY OF HEPATITIS A VIRAL INFECTION

Abstract

This study was carried out to determine the level of faecal pollution and the probability of hepatitis A viral infection associated with human consumption or contact with water from River Owena, Nigeria. Water samples were collected from River Owena on a weekly basis over a period of twelve (12) weeks from February to May, 2019. The concentration of faecal indicator bacteria were determined using standard microbiological method. The concentration of hepatitis A virus were determined using standard molecular method. The physicochemical properties of the water samples were determined using standard methods. The relationship, spatial variability and the level of variable loading of faecal indicator bacteria, hepatitis A virus and physiochemical characteristics of the water samples were analysed using a two-tailed Pearson’s rank correlation, cluster analysis and principal component analysis respectively. The probability of hepatitis A viral infection were assessed using quantitative microbial risk assessment. Results revealed that the mean count of Escherichia coli in the water samples ranged from 3.06 to 3.67 log10 CFU 100 ml- 1 whereas those of faecal coliforms ranged from 3.20 to 3.75 log10 CFU 100 ml-1 and the mean count of intestinal enterococci ranged from 2.40 to 3.00 log10 CFU 100 ml-1. The concentration of hepatitis A virus ranged from 0.00 to 6.42 log10 viral genome copies 100 ml-1. The values of Ph ranged from 6.02 to 7.32 and turbidity ranged from 5.18 to 8.86 NTU. The concentrations of the faecal coliforms showed a positive correlation with turbidity and nitrate. Cluster analysis showed that the water samples from River Owena may be grouped into two clusters based on the level of pollution. Results from the principal component analysis suggested strong positive loading for E. coli, Salmonella, nitrate and turbidity. The probability of hepatitis A virus infection ranged from 0.00 to 0.37 exceeding 10% thresholds level defined in the World Health Organization guideline on surface water. The findings from this study suggests that consumption of untreated water from River Owena or usage of the water for bathing or recreational activities such as swimming may pose a potential human health risk associated with hepatitis A viral infection.