A waterborne norovirus gastroenteritis outbreak in a school, eastern China

Abstract

In late 2014, a gastroenteritis outbreak occurred in a school in Shandong Province, eastern China. Hundreds of individuals developed the symptoms of diarrhoea and vomiting. Epidemiological investigation showed that food consumption was not linked to this outbreak, and unboiled direct drinking water was identified as the independent risk factor with a relative risk of 1·37 (95% confidence interval 1·03-1·83). Furthermore, examination of common bacterial and viral gastroenteritis pathogens was conducted on different specimens. Norovirus GI.1, GI.2, GI.6, GII.4, GII.6 and GII.13 were detected in clinical specimens and a water sample. GII.4 sequences between clinical specimens and the water sample displayed a close relationship and belonged to GII.4 variant Sydney 2012. These results indicate that direct drinking water contaminated by norovirus was responsible for this gastroenteritis outbreak. This study enriches our knowledge of waterborne norovirus outbreaks in China, and presents valuable prevention and control practices for policy-makers. In future, strengthened surveillance and supervision of direct drinking-water systems is needed.

Genotypic and Epidemiological Trends of Acute Gastroenteritis Associated with Noroviruses in China from 2006 to 2016

“…On the other hand, the seasonal behavior of NoV gastroenteritis is known to be influenced by host behavior. In particular, people crowding together and more time spent indoors are possible factors increasing human-to-human transmission of these viruses during winter [ 21 , 22 , 26 ]. In general, understanding the seasonal changes in NoV infection is important to be able to implement efficient surveillance and preventive measures for its control.…”

“…Among these factors, the climate in southern and eastern China, was humid and cold in winter, which is helpful to the reproduction of NoVs [ 24 , 25 ]. A high economic development level, resulted in dense populations which are at highest risks of the spread of NoVs [ 21 ]. Also, surveillance were implemented more strictly and efficiently in southern and eastern China [ 29 , 30 ].…”

“…NoV infections are also common problems in China [ 20 , 21 ]. China’s government launched the National Notifiable Disease Reporting System (NNDRS) for notification of infectious diseases in 2003 and enhanced it in 2006.…”

Identifying Potential Norovirus Epidemics in China via Internet Surveillance

“…Although norovirus infection is viewed as a self-limited illness, it might be still responsible for severe dehydration, and even potential death, in children and the elderly population [ 7 - 9 ]. Infection might be attributable to closed bedside care and exposure to vomit of contaminated food, water and aerosol of norovirus, and other factors such as prolonged time for viral shedding and the enhanced viability in the environment might play vital roles in improving transmissibility of norovirus [ 4 , 10 - 12 ]. Additionally, no obvious evidence supports the idea of there being a specific reservoir, and only the scattered speculation from available literature viewed immunocompromised individuals, elderly, and malnourished hosts as potential norovirus reservoirs [ 13 ].…”

“…Norovirus was ranked the second most common etiological agent only after rotavirus in children younger than 5 years in China [ 14 - 16 ]. Field surveys imply that unboiled water and contaminated food are the common causes of norovirus infection [ 12 , 17 ]. The high contagiosity, frequent virus mutation, and limited immune protection has resulted in more frequent epidemics of norovirus outbreak on the Chinese mainland since the winter of 2014, especially in schools [ 18 - 20 ].…”