New methods for the detection of viruses: call for review of drinking water quality guidelines.
Drinking water supplies which meet international recommendations for source, treatment and disinfection were analysed. Viruses recovered from 100 L-1,000 L volumes by in-line glass wool filters were inoculated in parallel into four cell culture systems. Cell culture inoculation was used to isolate cytopathogenic viruses, amplify the nucleic acid of non-cytopathogenic viruses and confirm viability of viruses. Over a period of two years, viruses were detected in 23% of 413 drinking water samples and 73% of 224 raw water samples. Cytopathogenic viruses were detected in 6% raw water samples but not in any treated drinking water supplies. Enteroviruses were detected in 17% drinking water samples, adenoviruses in 4% and hepatitis A virus in 3%. In addition to these viruses, astro- and rotaviruses were detected in raw water. All drinking water supplies had heterotrophic plate counts of < 100/mL, total and faecal coliform counts of 0/100 mL and negative results in qualitative presence-absence tests for somatic and F-RNA coliphages (500 mL samples). These results call for a revision of water quality guidelines based on indicator organisms and vague reference to the absence of viruses.
Grabow
W O
WO
Dept of Medical Virology, University of Pretoria, PO Box 2034, 0001 Pretoria, South Africa. grabow@med.up.ac.za
Taylor
M B
MB
de Villiers
J C
JC
D018929:Cell Culture Techniques; D004279:DNA, Viral / Q000032:analysis*; D004202:Disinfectants; D004784:Environmental Monitoring / Q000379:methods; D005374:Filtration; D017408:Guidelines as Topic; D006801:Humans; D016133:Polymerase Chain Reaction; D011634:Public Health; D011786:Quality Control; D012680:Sensitivity and Specificity; D014780:Viruses; D014881:Water Supply / Q000592:standards*
D004279:DNA, Viral; D004202:Disinfectants