Abstract
BackgroundNorovirus is an important cause of gastroenteritis both in children and adults. In China, few studies have been conducted on adult populations. This study aimed to determine the contribution of norovirus to gastroenteritis, characterize the features of norovirus infections, compare them with other pathogens, and test the effectiveness of the surveillance system.MethodsA citywide surveillance network on diarrhea patients was established. Samples were collected with intervals from both children and adults among diarrhea outpatients in hospitals and tested for viruses using rRT-PCR and for bacteria in CDCs. Patient information was acquired through interviews and recorded into a dedicated online system. The Pearsonχ2 test, multivariate logistic regression models and discriminant models were fitted into its comparisons with the non-norovirus group and other pathogens.ResultsNorovirus was detected in 22.91% of sampled diarrhea patients. The seasonal distribution of norovirus infections was different from non-norovirus patients (p < 0.001), with a half-year peak. Higher proportions of males (p = 0.001, OR = 1.303, 95% CI = 1.110-1.529), local citizens (p < 0.001) and officials/clerks (p = 0.001, OR = 1.348, 95% CI = 1.124-1.618) were affected with norovirus when compared with non-norovirus patients. Diarrhea patients affected with norovirus featured nausea (p < 0.001, OR = 1.418, 95% CI = 1.176-1.709) and vomiting (p < 0.001, OR = 1.969, 95% CI = 1.618-2.398), while fewer manifested fever (p = 0.046, OR = 0.758, 95% CI = 0.577-0.996) and abdominal pain (p = 0.018, OR = 0.815, 95% CI = 0.689-0.965). Children were more vulnerable to rotavirus (p = 0.008, OR = 1.637, 95% CI = 1.136-2.358) and bacteria (p = 0.027, OR = 1.511, 95% CI = 1.053-2.169) than norovirus. There was a seasonal difference between the GI and GII genotypes (p < 0.001). Officials or clerks were more easily affected with GI than GII (p = 0.006, OR = 1.888, 95% CI = 1.205-2.958).ConclusionsThis study was based on a citywide hospital-sentinel surveillance system with multiple enteric pathogens included. Norovirus was recognized as the most prevalent enteric pathogen in Shanghai. The seasonal peak was from October to April. Males had a higher prevalence than females. Local citizens and officials/clerks were more vulnerable to norovirus than other pathogens. Compared with rotavirus and bacteria, children were less frequently affected by norovirus. Nausea and vomiting were typical of norovirus, whereas fever and abdominal pain were uncommon symptoms of this pathogen. GI and GII infections were centered in different seasons. Officials and clerks were more easily affected by GI than GII.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-0922-z) contains supplementary material, which is available to authorized users.
Highlights
Norovirus is an important cause of gastroenteritis both in children and adults
Other than previous studies, which concluded that young children and elderly people were more vulnerable than other age groups [10,24], our study discovered that the highest detection rate was found in the youth group (19-44y) (25.97%), and the lowest in the children group (13.30%), with the elderly group in the middle (23.50%), whereas in a logistic model, the age distribution of NoV(+) patients could not be proved to be different from NoV(−) patients
Because of the small sample size and short surveillance time, we did not perform further research among sole-infections and coinfections and other stratification analyses. This was the first study on norovirus among all age groups in Shanghai
Summary
Norovirus is an important cause of gastroenteritis both in children and adults. Diarrheal disease morbidity and mortality have been in decline globally, but around 1.7-5 billion cases of diarrhea [1] and nearly 1.7 million diarrheal deaths still occur each year [2], the great majority of which are among young children in developing countries [3]. It was concluded that an average of 570–800 deaths, 56,000-71,000 hospitalizations, 1.7-1.9 million outpatients visits, and 19–21 million total illnesses occurin the United States each year as a result of norovirus infections [8]. It is estimated that the economic burden of norovirus infections approached or exceeded US$284 million annually in health care charges in the United States [11]
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