Groundwater Contamination of Noroviruses in Busan, Ulsan, and Gyeongsangnam-do, Korea

To inspect norovirus contamination of groundwater in south eastern areas of Korea, a systematic sur-vey of groundwater in Busan, Ulsan, and Gyeongsangnam-do was performed for two years from 2009 to 2010. For this purpose, we first optimized the nested reverse transcription-PCR condition by design-ing two sets of primers for the detection of norovirus genogroups, GI and GII. Of 145 samples, 21 (25.9%) and 15 (23.4%) were norovirus positive in the dry season (April to June) and wet season (July to August), respectively. The detection frequencies of norovirus in Busan, Ulsan, and Gyeongsangnam-do were 15%, 7%, and 32%, respectively, reflecting a geographical difference in their distribution. The GI and GII isolates were 5 and 31, respectively, indicating the prevalence of GII in the tested areas. According to phylogenetic analysis of their nucleotide sequences, all of the GI isolates were identified to genotype GI.5 whilst the GII isolates were divided into two genotypes, GII.3 and GII.4. Neither physical-chemical parameters such as pH, temperature, oxidation-reduction potential, and dissolved oxygen, nor microbial indicators of water quality such as total bacteria, total coliforms, and Escherichia coli were statistically correlated with contamination of norovirus in the groundwater. Interestingly, however, the presence of norovirus was closely correlated with low turbidity (<0.50 NTU). The present study suggests that periodical monitoring of norovirus in groundwater is necessar