Epidemiology and Infection

Original Papers


Epidemiological and molecular analysis of a waterborne outbreak of norovirus GII.4

X. ZHOUa1a2, H. LIa1 c1, L. SUNa1, Y. MOa1, S. CHENa3, X. WUa3, J. LIANGa3, H. ZHENGa1, C. KEa1, J. K. VARMAa4, J. D. KLENAa4, Q. CHENa1, L. ZOUa1 and X. YANGa1 c1

a1 Guangdong Provincial Centre for Disease Control and Prevention, Guangdong, China

a2 Guangzhou Red Cross Hospital Affiliated to Jinan University, Guangdong, China

a3 Field Epidemiology Training Program of Guangdong Provincial Centre for Disease Control and Prevention, Guangdong, China

a4 China–US Collaborative Program on Emerging Infectious Diseases, Beijing, China and United States Centers for Disease Control and Prevention, Atlanta, GA, USA


Contaminated water is one of the main sources of norovirus (NoV) gastroenteritis outbreaks globally. Waterborne NoV outbreaks are infrequently attributed to GII.4 NoV. In September 2009, a NoV outbreak affected a small school in Guangdong Province, China. Epidemiological investigations indicated that household use water, supplied by a well, was the probable source (relative risk 1·9). NoV nucleic acid material in concentrated well-water samples was detected using real-time RT–PCR. Nucleotide sequences of NoV extracted from diarrhoea and well-water specimens were identical and had the greatest sequence identity to corresponding sequences from the epidemic strain GII.4-2006b. Our report documents the first laboratory-confirmed waterborne outbreak caused by GII.4 NoV genotype in China. Our investigations indicate that well water, intended exclusively for household use but not for consumption, caused this outbreak. The results of this report serve as a reminder that private well water intended for household use should be tested for NoV.

(Received January 12 2012)

(Revised January 17 2012)

(Accepted February 15 2012)

(Online publication March 08 2012)

Key words

  • Gastroenteritis;
  • norovirus;
  • outbreak;
  • well water


c1 Author for correspondence: Dr H. Li or Professor X. Yang, Guangdong Provincial Centre for Disease Control and Prevention, Guangzhou, China, 510300. (Email: gdcdclihui@163.com) [H. Li] (Email: yangxingfen@cdcp.org.cn) [X. Yang]