Development of sample storage methods for detecting enteric viruses in environmental water

In a field survey of enteric viruses, water samples collected sometimes need to be stored for a long duration before analysis is performed. The aim of this study was to develop an appropriate sample storage method for detecting viruses in environmental water. Three types of sample storage methods were evaluated using MilliQ water, pond water, and treated sewage inoculated with poliovirus and norovirus: (i) storage followed by the full concentration procedure, (ii) filtration and storage followed by the remaining concentration procedure, and (iii) the full concentration procedure before storage. The recovery of norovirus on day 0 of inoculation was 110.2 ± 38.2% (n = 2), which was comparable to that of poliovirus. During sample storage for up to 13 days, virus recovery showed different patterns of decrease, depending on the storage method, sample type, and storage temperature. Among the three methods tested, the method of storing the eluted samples was judged to be most appropriate for detection of viruses from water samples. This method does not require any special equipment and can be easily adopted in field surveys, especially in developing countries.