Relationship of viruses and indicator bacteria in water and wastewater of Israel

Different aquatic resources of Israel were monitored to obtain information on the occurrence of enteroviruses and their relationship to the bacteriological indicators of water quality. A total of 155 samples of groundwater, surface water, potable water and swimming pool water were examined, of which 45 (29.0%) yielded virus. Echovirus type 7 was the most predominant, followed by poliovirus 1, echovirus 6 and coxsackieviruses B2, B5 and B6. Virus was isolated on several occasions when the water in question met current bacteriological standards. Viruses were isolated from water samples with no detectable fecal or total coliform bacteria. No significant statistical correlation could be determined between the occurrence of bacterial indicators and the presence of viruses. This study raises serious doubts about the validity of the indicator bacteria concept to predict the virological quality of water, particularly in countries with a high incidence of enteric viral disease.