title: [Epidemiology of confirmed and suspected norovirus outbreaks in Shanghai, 2010-2014].
abstract: OBJECTIVE
  To understand the epidemiologic characteristics of confirmed and suspected norovirus outbreaks in Shanghai during 2010-2014.
  
  
  METHODS
  The investigation reports of confirmed and suspected norovirus outbreaks in Shanghai from 2010 to 2014 were analyzed.
  
  
  RESULTS
  A total of 80 norovirus outbreaks, involving 2 399 cases, were reported during this period, and the overall attack rate was 4.17%. The median of the outbreak duration was 4.5 days and the incidence peaked 2 days later averagely for an outbreak. The outbreaks mainly occurred in autumn and winter, 53 outbreaks occurred during October-February, accounting for 66.25%. Seventy five outbreaks occurred in schools, child care settings and nursing houses, accounting for 93.75%. The attack rates in hospitalized patients and the elders in nursing houses were higher than those in pre-school and school aged children, the differences were statistically significant (χ² =683.12, P<0.01). The attack rates in medical staff and nurses in hospitals and nursing houses or staff in pre-schools and schools were lower. Vomiting, the main clinical symptom, occurred in 1 900 cases (79.20%), diarrhea and fever developed in 694 cases (28.93% ) and 364 cases (15.17% ) respectively. The differences were statistically significant (χ² =2 251.48, P<0.01). The outbreaks were mainly caused by short common exposures and contact with cases.
  
  
  CONCLUSIONS
  The surveillance for norovirus infection should be strengthened in hospitals, schools and others with the crowed during autumn-winter. The protection of risk population should be enhanced.
authors: Department of Acute Infectious Disease, Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China.
authors: Jian
authors: J
authors: Li
authors: Department of Acute Infectious Disease, Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China.
authors: Hao
authors: H
authors: Pan
authors: Department of Acute Infectious Disease, Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China.
authors: Wenjia
authors: W
authors: Xiao
authors: Department of Acute Infectious Disease, Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China.
authors: Jiayu
authors: J
authors: Hu
authors: Department of Acute Infectious Disease, Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China; Email: yuanzhengan@scdc.sh.cn.
authors: Zheng'an
authors: Z
authors: Yuan
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003967:Diarrhea; D004196:Disease Outbreaks; D005334:Fever; D006707:Homes for the Aged; D006761:Hospitals; D006801:Humans; D015994:Incidence; D008503:Medical Staff; D029322:Norovirus; D009735:Nursing Homes; D012574:Schools; D012621:Seasons; D014839:Vomiting