The Epidemic Characteristics Of Infectious Diarrheal Pathogens Of China During 2010 To 2014

Objective:To acquire the basic data and etiological characteristics of infectious diarrhea in China, determine the clinical symptoms of cases infected by different pathogens, and thus make up for deficiencies and fallacies of national surveillance. The new findings of our study would provide benefit the complement of the policy and management of national infectious diarrhea control and prevention.Methods:A cross-sectional surveillance was conducted among 17 provinces of China from 2010 to 2014.The acute diarrhea outpatients were collected from clinics or hospitals. A questionnaire was used to survey demographics and clinical features. The feces samples were tanken for laboratory detection of 5 virus and 17 bacteria. The etiology of diarrhea cases was analyzed. The correlation between patients’ characteristics and pathogens, pathogens and clinical symptoms were conducted. The study also compared the differences of etiologic spectrum for cases from different ages and cases from different areas. Stata 12.0 was used to analyze the data.Results:During the period from Jan 2010 to Dec 2014, a total of 28704 outpatients were enrolled from 17 provinces of China. Virus positive rate was 36.61%. Rotavirus and Norovirus were the most prevalent, with the positive rates of 15.92% and 14.44%, respectively. The overall bacterial isolation rate was 15.80%. The isolation rate of diarrheogenic Escherichia coli was the highest, up to 7.13%. The isolation rates of Salmonella (4.63%) and Shigella (3.89%) ranked following and that of other bacteria were close to or less than 1%.The multiple logistic regression analysis showed that there was no significant sexual difference in occurrence of infectious diarrhea, while the age of case and the season were significantly associated with the pathogen infection. The children under 2 years old had the highest risk for viral infection and the reduced risk for age were observed.The older age groups had higher risk for bacterial infection than viral infection; while the younger age groups had higher risk for viral infection than bacterial infection. Older children had the highest risk for the infection of EaggEC, EPEC, STEC, Salmonella, Shigella and Campylobacter. Meanwhile, the adults had the highest risk for infection of ETEC, EIEC, Vibrio and Plesimonas shigelloides. For seasonal features, all but Yersinia and Vibrio, the risks of bacteria were higher in summer and autumn while lower in winter and spring. The seasonal summits of viral infection varied with the different viruses.There were obvious different symptoms between virus and bacterial infection. The common clinical symptoms of viral diarrhea were characterized by watery stool, vomiting and without WBC and RBC in stool routine detection. However, the common symptoms of bacterial diarrhea were characterized by mucus or bloody stool, with WBC or RBC in stool routine detection, but vomiting rarely. It’s worthy to note that, the symptoms of Vibrio infection looked like viral diarrhea. The symptoms of Salmonella and Shigella infection were very similar and it’s impossible to distinguish with symptoms only.The infection risks of Rotavirus, Norovirus, Adenovirus, EAggEC, STEC and Salmonella were higher in children than in adults. But the risks of ETEC, EIEC, Vibrio and P. shigelloides were higher in adults than in children. The proportions of Shigella serogroups showed no obvious differences between childhood cases, while the diversity of DEC classes were observed between the two groups:EAggEC was the primary class of DEC in children and the proportion of ETEC in adults was much higher than it in children. The etiologic spectrums of southern case and northern cases were similar though the infection rates were different. The infection rates of Shigella and A.hydrophila in rural areas were significantly higher than large cities. The infection risks of Shigella reduced with the urbanization development. But the infection risks of Salmonella didn’t have the significant differences among rural areas, rural-urban fringe zones and large cities. S.Flexneri was the dominant serogroup of Shigella in rural infections and S.sonnei was the main serogroup in urban infections. However, the classes of DEC were similar among rural areas, rural-urban fringe zones and large cities.Conclusions:The susceptible ages of bacterial diarrheal patients are older than viral infection cases. Fecal properties and stool routine inspection results are the main divergences between bacterial and virus diarrhea. But the clinical features of Vibrio infection are similar to viral diarrhea. The symptoms of Salmonella and Shigella infection are almost identical.The etiology of Chinese large cities resembled developed countries and the etiology of Chinese economically depressed areas are similar to developing counties worldwide. Shigella and A. hydrophila are the major differently-infected pathogens between the developed and developing areas. A.hydrophila is infered to be an improtant diarrheogenic bacterium in China but was ignored in the pase.