Age, primary symptoms, and genotype characteristics of norovirus outbreaks in Shanghai schools in 2017

Abstract

Sixty norovirus outbreaks that occurred in Pudong District, Shanghai in 2017 and affected 959 people were summarised. Of the outbreaks, 29 (48.3%), 27 (45.0%), and 4 (6.7%) occurred in kindergartens, primary schools, and middle schools, respectively. Although the total number of outbreaks peaked in March (13/60, 21.7%), outbreaks in kindergartens and primary schools peaked in April (6/29, 20.7%) and March (8/27, 29.6%), respectively. Primary schools had the highest median number of cases per outbreak (19) and the highest proportion of cases (54.6%). The male-to-female case ratio differed among school classifications, with the highest male case ratio (69.2%) occurring in middle schools. Primary symptoms also differed across the school classifications. Molecular virology analysis showed that a single viral strain caused each outbreak at each school. In turn, 50.6, 28.8, and 20.6% of cases were infected by GII.4, GII.2, and GII.17, respectively. Vomiting was seen in 98.2, 97.3, and 88.6% of the subjects infected with noroviruses GII.17, GII.4, and GII.2, respectively, and nausea in 73.6, 43.9, and 39.0%. In conclusion, noroviruses mainly affect primary school and kindergarten students. GII.4, GII.2, and GII.17 are the main epidemic strains in the local area, and the primary symptoms differed by age and genotype.

The Preventive Effect of Lactoferrin-Containing Yogurt on Gastroenteritis in Nursery School Children—Intervention Study for 15 Weeks

“…Vomiting is the primary and dominant symptom of infectious enteritis [26]. The norovirus genotypes of GII.2 and GII.4 are common in Japan, and vomiting is the major symptom of the GII.2 and GII.4 norovirus [1,27]. However, our results were not consistent with these references.…”

Risk factors associated with outbreaks of seasonal infectious disease in school settings, England, UK

“…The finding that primary schools were disproportionately affected by outbreaks is consistent with existing literature [5,9,26,27]. Younger children are known to have a greater vulnerability to infection, higher virus shedding and poorer levels of hand and respiratory hygiene which increase the risk of illness [1].…”

Epidemiological and clinical differences between sexes and pathogens in a three-year surveillance of acute infectious gastroenteritis in Shanghai

“…The virus panel was established with routine diarrhea surveillance data that were accumulated by local Centers for Disease Control and Prevention and by reference to information from peers 20–23 . Rotavirus, norovirus, enteric adenovirus, astrovirus, sapovirus, mimiviruses, aichivirus, bocavirus, parechovirus, cytomegalovirus, hepatitis A, coronaviruses, picornaviruses, toroviruses, and other enteroviruses were detected by polymerase chain reaction (PCR) or reverse transcription PCR using primer sets, as reported previously 2,10,12,20–23 .…”

“…Viral detection is another vital part of the acute gastroenteritis control and prevention strategy established by the local health administration department. Gastroenteritis virus detection was performed according to methods reported by other peers 2,10,12,20,21 . Briefly, fecal specimens were prepared as 10% (w/v) suspensions in distilled water and then centrifuged for 10 min at 10000 g in a 1.5 ml collection tube (Biovisualab, Shanghai, China) to remove debris.…”

“…Thus, further evaluation of differences in sex, infection source, transmission route, symptoms as well as clinical laboratory tests between viral and bacterial gastroenteritis has clinical significance. In addition, Shanghai is an international metropolis that had 24.2 million residents and 320 million tourists in the year of 2017, and high population density is a major factor promoting acute gastroenteritis epidemics 2,3,9–12 . So far, long-term acute gastroenteritis surveillance data with a large sample size from Shanghai are still scarce.…”