ABSTRACT
Objective:To analyze the epidemiological characteristics of an aggregational gastroenteritis and determine the genotypes of sapovirus， and to provide scientific basis for formulating effective control strategies. Methods:Unified case definition， active case search and descriptive epidemiology were used to analyze the epidemic. Feces or anal swabs of untreated students， teachers， canteen staff as well as canteen environment samples were collected. Norovirus and sapovirus nucleic acid tests were conducted by real-time fluorescent RT-PCR， and sapovirus nucleic acid was amplified by conventional RT-PCR. The gene region of capsid protein was analyzed by MEGA7.0 software and phylogenetic tree was constructed. Results:A total of 12 cases were reported in the epidemic， and the incidence rate was 44.44%. All reported cases， with vomiting symptoms， were found in the same class. The epidemic showed a point-based outbreak. The first case became the source of infection in class， and the epidemic lasted for 8 days. Real-time fluorescent RT-PCR assay confirmed that five children's feces were positive for sapovirus nucleic acid， and the first-episode children's feces were positive for sapovirus and GII norovirus nucleic acid. Sequence alignment result showed that the sapovirus strains belonged to GI.1 type with homologous genes. Conclusion:Based on the clinical manifestations， field epidemiological investigation and laboratory test results， we confirm that the first case of the epidemic in class is caused by GI.1 sapovirus infection. The epidemic is effectively controlled by comprehensive measures such as case isolation and disinfection.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the epidemiological characteristics of an acute gastroenteritis outbreak in a nursing home caused by norovirus (NoV) and the genotype of the pathogen.</p><p><b>METHODS</b>On January 29th 2013, a total of 26 acute gastroenteritis patients infected by norovirus were reported in the nursing home of Jinshan, Shanghai. A questionnaire was used to acquire information of patients involved in the outbreak, 9 stool or anal swab samples were collected from 9 patients without treatment by simple random sampling method, and 4 environmental samples from the surface of doorknobs or toilets were collected. The samples were detected by Real-time PCR for NoV, and positive samples were then amplified by routine RT-PCR. The PCR products were purified, sequenced, and aligned by comparing sequences in GenBank. Phylogenetic trees were constructed by using Clustal X, employing MEGA 5.1 program package.</p><p><b>RESULTS</b>For the 26 patients, 7 were men and 19 were women.8 samples were found NoV positive among the 13 samples when detected by real-time PCR. The sequence alignment showed that the nucleotide sequence homology between Jinshan08 and Jinshan12 strain which obtained sequencing signal was 100%. The phylogenetic analysis revealed that Jinshan08, Jinshan12 and GII.e/NV2634/BCN/Spain/2008 strains in the RdRp region were on the the same branch of evolutionary tree, the confidence level was 99%, and in the N/S region of the Capsid, 2 other strains and Lordsdal strain were in the same branch, the confidence level was 97%.</p><p><b>CONCLUSION</b>It was confirmed that the acute gastroenteritis outbreak was caused by the new GII.4 NoV recombinant.</p>