OBJECTIVETo analysis the etiological and epidemiological characteristics of the reported infectious diarrhea (other than cholera, dysentery, typhoid and paratyphoid) cases in China in 2011.

METHODSA total of 836 591 reported infectious diarrhea cases were collected from "China Information System for Disease Prevention and Control" since first week to fifty-second weeks in 2011, 59 929 out of which were laboratory-confirmed. The information of thirty public health emergencies relevant with infectious diarrhea was collected from "Emergency Public Reporting System" between first week and fifty-second weeks in 2011. The epidemiological characteristics of reported cases, confirmed cases and outbreaks, and the pathogenic spectrum of confirmed cases were then analyzed.

RESULTSIn 2011, 836 591 infectious diarrhea cases (other than cholera, dysentery, typhoid and paratyphoid) were reported, and the incidence rate was 62.39/100 000. More than half patients were children aged under 5 year-old, accounting for 52.13% (436 098/836 591) and the incidence rate was 447.06/100 000 (436 098 cases). Most of the ill children were scattered, accounting for 50.53% (422 752/836 591). Reported cases showed two incidence peaks, with a summer peak from twenty-third weeks to thirty-fifth weeks, accounting for 34.33% (287 231/836 591) and a winter peak from forty-third weeks to fifty-second weeks, accounting for 23.54% (196 939/836 591). Cases distributed all over China, the incidence in Beijing (253.00/100 000 (49 619 cases)), Tianjin (244.34/100 000 (31 614 cases)), Zhejiang (204.42/100 000 (111 257 cases)), Ningxia (132.16/100 000 (9328 cases)) and Guangdong (127.40/100 000 (132 880 cases)) ranked the top five. Among the 30 public health emergencies, 5 outbreaks had lab tested pathogenic results, including 4 were norovirus-induced. Laboratory-confirmed cases accounted for 7.16% (59 929/836 591) of the case reported, including 56 687 viral cases and 3242 bacterial cases. Rotavirus cases took the highest proportion of viral cases, at 97.35% (53 612/55 185); and 97.15% (53 612/55 185) of which were children aged under 5 year-old. 82.42% (45 480/55 185) of the cases distributed in Guangdong and Zhejiang province, with the incidence peak from fiftieth weeks to fifty-first weeks, accounting for 15.42% (8508/55 185) of the whole year cases. The main pathogens of bacterial diarrhea were Salmonella, Vibrio parahaemolyticus and Escherichia coli, accounting for 48.43% (1570/3242), 32.20% (1044/3242) and 8.57% (278/3242) respectively, with the incidence peak from thirty-first weeks to thirty-fifth weeks, accounting for 23.01% (746/3242). Salmonella infection patients were mainly from Shanghai, Guangdong and Zhejiang province (91.59% (1438/1570)), Vibrio parahaemolyticus patients were mainly from Shanghai (80.94% (845/1044)), and Escherichia coli patients were mainly from Guangdong province (84.17% (234/278)). Salmonella patients were concentrated in 0-9 years group, accounting for 42.36% (665/1570), while Vibrio parahaemolyticus patients in 20-39 years group, accounting for 81.99% (856/1044), and Escherichia coli patients in under 1 year old and 20-39 years group, accounting for 63.67% (177/278).

CONCLUSIONIn China, children aged under 5 year-old should be the priority population in surveillance of infectious diarrhea. Rotavirus is the main pathogen causing infectious diarrhea. The lab-testing and case-reporting capabilities differed greatly among areas.