Procedure voor virusdetectie in water ten behoeve van het Nederlandse Waterleidingbesluit 2001

This report describes the various methods available for detection of viruses in water in the Netherlands. Research data on viruses in water sources used for the production of drinking water and the removal of viruses through applied treatment processes are important to be able to assess the 10-4 infection risk allowed in Dutch drinking water guidelines. According to these guidelines Cryptosporidium, Giardia and (entero)viruses need to be assessed for infection risk, indicating that, besides enteroviruses, other pathogenic viruses of possible importance for the drinking water supply will have to be included. Noro- and rotaviruses are examples of such important pathogenic viruses, considering that these are the most common viruses causing viral gastroenteritis in the Netherlands. By combining new molecular biological techniques and common methods for virus concentration and cell culture, we arrived at the procedure for detecting viruses in water samples proposed below. The individual techniques are explained in detail in the report: viruses are filtered from water by negative membrane filtration; the eluate is further concentrated through two-phase separation for the reverse transcriptase-polymerase chain reaction (RT-PCR) and ultrafiltration for cell culture; RT-PCR is performed to determine the presence of viruses in the water samples; cell culture is performed for cases of positive enterovirus RT-PCR to determine the infectivity. Bacteriophages are analysed in source waters and in different stages of the treatment process to be able to calculate the amount of virus in drinking water. Advantages and disadvantages of the present methods are explained and discussed in this report. New developments in viral diagnostics, such as optimising RNA extraction or combining cell culture and molecular techniques, have been suggested as a possible means of optimising the procedure presented