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Emerging norovirus strain triggers gastroenteritis outbreaks in China
The emerging norovirus genotype GII.17 was largely responsible for outbreaks of nonbacterial gastroenteritis in numerous Chinese cities during the 2014-15 winter season, according to recent data.
In the study, investigators responded to an increase in the number of norovirus outbreaks reported to the Guangdong Provincial Center for Disease Control and Prevention in late 2014. These outbreaks consisted of at least 20 acute gastroenteritis cases within 3 days. The researchers tested samples from each outbreak for norovirus and intestinal bacteria. Samples that tested positive for norovirus were genotyped, and between five and 10 samples per outbreak were randomly identified for sequencing. The researchers defined the major causative norovirus genotype in each outbreak as the one detected in more than 80% of outbreak samples.
From November 2014 through January, there were 29 outbreaks, including 2,340 cases, reported. By comparison, there were nine outbreaks and 949 cases during the previous winter, the researchers wrote. Genotype GII.4/Sydney/2012 occurred in 48% of outbreaks between January 2013 and October 2014.
The first detection of GII.17 occurred in Guangzhou in November 2014 and subsequently spread quickly. Through January, 10 cities within the Guangdong province reported GII.17 outbreaks, representing 83% of all outbreaks. After comparing sequences from archived strains of GII.17, the researchers said the genotype in Guangdong is a newly emerged variant that most closely resembles strains reported in Taiwan, Korea and Japan.
“The distribution of GII.17 genotype among patients with sporadic cases of gastroenteritis remains unknown,” the researchers wrote. “In future studies, epidemiologic and virologic surveillance should be broadened to better clarify virologic, clinical, and epidemiologic patterns of this newly emerged norovirus.” – by Jen Byrne
Disclosure: The researchers report no relevant financial disclosures.