Gastroenteritis outbreaks caused by Norovirus genotype II.7 in a college in China (Zhuhai, Guangdong) in 2011.

BACKGROUND: Noroviruses are the most common cause of epidemic gastroenteritis worldwide. Noroviruses are comprised of at least five genogroups (GI-GV) and >35 genotypes. GII.7 is a nonpredominant genotype associated with Norovirus outbreaks. On November 17, 2011, Zhuhai Center for Disease Control monitored an increasing number of gastroenteritis cases at a local college. To determine the causes and control the outbreak effectively, we carried out an epidemiologic investigation. METHODS: Suspected cases were defined as those with one of the following symptoms: nausea, vomiting, abdominal pain, or diarrhea presenting on or after November 15 among the people who lived at the college. Probable cases were defined as cases with vomiting or diarrhea over three times per day on or after November 15. Confirmed cases were suspected or probable cases positive for Norovirus (nucleic acid). We conducted a case-control study to identify risk factors of the outbreak. Norovirus was tested by real-time reverse transcription-polymerase chain reaction, and Norovirus polymerase chain reaction products were further sequenced. RESULTS: In total, 63 cases were identified, which were scattered in all 14 departments of the college. The outbreak lasted for 84 h. Time distribution mode indicated a point-source outbreak. Fifty-one cases and 94 controls were contacted. Seventy-five percent of the cases compared to 19% of the controls were exposed to delicatessens (various salad and meat products) from the "Y" convenience store (odds ratio=12, 95% confidence interval 5.4-28). Laboratory tests showed 14 of the 15 cases and two asymptomatic food handlers were positive for Norovirus nucleic acid. There was 100% similarity between the cases and the food handlers when we compared the nucleotide sequences of Norovirus, which clustered with GII.7 genotype. CONCLUSIONS: Delicatessens from the "Y" convenience store were associated with the GII.7 Norovirus outbreak. We strongly recommend food supervision and quality control in convenience stores to decrease the risk of future Norovirus outbreaks.

[The current epidemic situation and surveillance regarding hemorrhagic fever with renal syndrome in China, 2010].

OBJECTIVE: To analyze the surveillance data on hemorrhagic fever with renal syndrome (HFRS) including the epidemiological characteristics and trend of the disease, in 2010. METHODS: Descriptive methods were conducted to analyze the surveillance data in 2010 which were collected from the internet-based National Notifiable Disease Reporting System and 40 HFRS sentinels in China. RESULTS: There were 9526 cases of HFRS reported in 2010 in the country with an annual morbidity of 0.71/10(5), which was higher than that reported in 2009. And the case fatality rate in 2010 was 1.24%. During the year 2010, most cases were reported in spring and autumn-winter season, with November as the peak month. The proportion of cases reported in autumn-winter season was higher than that in spring. The number of cases reported in males was higher than that in females among all the age groups, and similar pattern of mortality could be seen in most of the age groups. The percentage of cases over 60 years old had increased in recent years. Farmers were still under the highest risk. Density and the virus-carrying rate of animal hosts, as well as the infection rate were relatively stable and similar to the previous findings. As to the prevailing species, Apodemus agrarius and Rattus norvegicus were still the most common and leading animal hosts. However, the dominant species in sentinel of Yunnan were Rattus flavipectus and Eothenomys miletus respectively, and a new hantavirus called LUXV was found, namely Eothenomys miletus. CONCLUSION: HFRS cases were widely distributed in most provinces of China, but cases mainly focus on certain areas and present the nature of aggregation. The risk of outbreak could not be ruled out for variety of factors. Population characteristics and seasonal fluctuation had been changing.