Objective: To investigate the epidemiological features of notifiable infectious diseases in Zhejiang Province in 2021, so as to provide the evidence for formulating infectious disease control measures. Methods: The data pertaining to notifiable infectious diseases reported in Zhejiang Province in 2021 were retrieved from the Infectious Disease Surveillance System of China Information System for Disease Control and Prevention. The incidence and mortality of notifiable infectious diseases in Zhejiang Province in 2021 were descriptively analyzed. Results: Totally 29 types of notifiable infectious diseases with 396 623 cases and 391 deaths were reported in Zhejiang Province in 2021, with a reported incidence of 614.28/105 and a reported mortality of 0.605 6/105, respectively. There were 93 204 cases with class B notifiable infectious diseases, with a reported incidence rate of 144.35/105 and 303 419 cases with class C notifiable infectious diseases, with a reported incidence rate of 469.92/105; while no cases with class A notifiable infectious diseases were reported. Syphilis (39.45/105), tuberculosis (37.12/105), viral hepatitis (31.90/105) and gonorrhea (26.34/105) were the four most common class B notifiable infectious diseases, and AIDS (0.477 0/105) and pulmonary tuberculosis (0.116 2/105) were the two most deadly class B notifiable infectious diseases, while hand, foot and mouth disease (192.00/105), other infectious diarrhea (184.24/105) and influenza (86.45/105) were the three most common class C notifiable infectious diseases. According to the transmission route, intestinal and respiratory infectious diseases were the two most common infectious diseases, with reported incidence rates of 384.10/105 and 133.73/105, respectively; and according to the reported region, the highest incidence of class B notifiable infectious diseases was reported in Zhoushan and Ningbo cities, and the highest incidence of class C notifiable infectious diseases was reported in Ningbo City. Totally 1 101 COVID-19 cases were reported in Zhejiang Province in 2021, including 712 confirmed cases and 389 asymptomatic cases, and no deaths occurred. Conclusions The reported incidence of notifiable infectious diseases declined in Zhejiang Province in 2021 as compared to that prior to COVID-19 epidemics, with remarkable reductions in the incidence of respiratory and intestinal infectious diseases. The management of pulmonary tuberculosis, viral hepatitis and AIDS requires to be reinforced during the containment of COVID-19, to prevent the seasonable epidemic of influenza, hand, foot and mouth disease and other infectious diarrhea in Zhejiang Province.

Objective: To establish a prediction model of herpangina epidemic trend based on Baidu index and hand, foot and mouth disease, so as to provide insights into analyses of communicable disease epidemics with limited or missing surveillance data. Methods: The incidence of hand, foot and mouth disease in Zhejiang Province during the period from the first week of 2015 through the 39th week of 2021 was retrieved from the China Information System for Disease Control and Prevention, and the Baidu index of hand, foot and mouth disease and herpangina was collected via the Baidu search engine during the same period. The correlation between the Baidu index and time series of hand, foot and mouth disease was examined using wavelet analysis. In addition, a random forest training model was created based on the Baidu index and incidence of hand, foot and mouth disease, and the fitting effectiveness was evaluated using the mean percentage error, while the Baidu index of herpangina was included in the model to predict the epidemic trend of herpangina during the study period. Results: The Baidu index of herpangina and hand, foot and mouth disease, and the Baidu index and incidence of hand, foot and mouth disease all appeared two peaks at the 26th and 52th week. The phase difference was less than 0.1 week between the Baidu index and time series of hand, foot and mouth disease, and the mean percentage error of the training model was 13.07%, with high concordance between the predicted number and actual report number of cases with hand, foot and mouth disease. The numbers of herpangina cases were predicted to be 28 822, 27 341, 28 422, 51 782, 52 457 and 5 691 from 2015 to 2020, and there were totally 48 702 herpangina cases reported until the 39th week of 2021. Like hand, foot and mouth disease, the incidence of herpangina peaked between May and July. Conclusion The random forest training model based on the Baidu index and incidence of hand, foot and mouth disease is feasible to predict the epidemic trend of herpangina.

Objective: To investigate the characteristics of public health emergencies and related information in schools of Zhejiang Province from 2012 to 2021, so as to provide insights into the management of public health risks in schools. Methods: The public health emergencies and related information in schools of Zhejiang Province during the period from 2012 to 2021 were retrieved from the Public Health Emergency Management Information System of Chinese Disease Prevention and Control Information System. The type, temporal distribution and regional distribution of the events and the type of schools were analyzed, and the trends in disease attack rates were evaluated. Results: A total of 1 284 public health emergencies and related information were reported in schools of Zhejiang Province from 2012 to 2021, accounting for 72.34% of all public health emergencies and related information, and a total of 40 562 cases were reported, accounting for 87.72% of all cases; no death was recorded. There were 1 276 infectious disease events reported, accounting for 99.38%, and norovirus enteritis (649 cases), varicella (281 cases), influenza (181 cases), hand, foot and mouth disease (94 cases) and mumps (22 cases) were predominant infectious diseases, accounting for 95.56% of all public health emergencies and related information in schools. The number of public health emergencies and related information in schools peaked during the period between March and June (361 events, 28.12% of all events) and the period between November and December each year from 2012 to 2021 (629 events, 48.99% of all events), and the events occurred across 11 cities of Zhejiang Province, with the largest number of events reported in Hangzhou City (507 events). In addition, there were 627, 328 and 242 events reported in primary schools, kindergartens, and middle schools, accounting for 93.22%, and the events predominantly occurred in city schools. Nevertheless, there were no significant changes in the trends for attack rates of norovirus enteritis, varicella, influenza and hand, foot and mouth disease and mumps in schools of Zhejiang Province from 2012 to 2021. Conclusions Norovirus enteritis, varicella, influenza, hand, foot and mouth disease and mumps were the predominant types of public health emergencies and related information in schools of Zhejiang Province from 2012 to 2021, and the largest number of events were reported in primary schools.

Objective: To analyze the epidemiological characteristics of overseas imported cases with coronavirus disease 2019 (COVID-19) in Zhejiang Province, so as to provide insights into containment of overseas imported COVID-19. Methods: The pertaining to overseas imported COVID-19 cases in Zhejiang Province during the period between January 1, 2020 and May 31, 2022 were captured from the Chinese Disease Prevention and Control Information System. The temporal, spatial and population distributions, the duration from entry to the first time of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid test, and COVID-19 vaccination of overseas imported COVID-19 cases were analyzed using a descriptive epidemiological method. Results: A total of 1 535 overseas imported COVID-19 cases were reported in Zhejiang Province during the period between January 1, 2020 and May 31, 2022, including 596 confirmed cases and 939 asymptomatic infections, and all reported cases were imported from 102 countries and territories. Overseas imported COVID-19 cases were reported in each month during the period between March 2020 and May 2022 except May 2020, and the mean monthly number of reported overseas imported COVID-19 cases was 125 during the period between December 2021 and May 2022. Overseas imported COVID-19 cases were reported across 11 cities of Zhejiang Province, with the largest numbers reported in Hangzhou (978 cases) and Jiaxing cities (177 cases), and imported cases were reported in 76.09% of counties (districts) in Zhejiang Province. The overseas imported COVID-19 cases were predominantly identified among individuals with Chinese nationality (88.79%), at ages of 20 to 39 years (59.09%), and students (21.82%), workers (17.20%) and business servants (17.00%) were predominant occupations among the overseas imported COVID-19 cases. The median duration from entry to the first time of positive SARS-CoV-2 nucleic acid test was 3.98 (7.06) d during the period between January 1, 2020 and May 31, 2022, and was 3.23 (4.97) d during the period between December 1, 2021 and May 31, 2022, which was significantly shorter than that during the period between January 1, 2020 and November 30, 2021 (P<0.001). The proportion of normal and more severe types of COVID-19 was 15.69% among cases without COVID-19 vaccination, which was significantly higher than that (7.77%) among those receiving booster vaccination (χ2=5.345, P=0.021), but was not significantly different from that (12.65%) among those receiving full-dose vaccination (χ2=0.971, P=0.324). Conclusions Students with Chinese nationality, workers and business servants were predominant among overseas imported COVID-19 cases in Zhejiang Province until May 31, 2022. The duration from entry after December 1, 2021 to identification of overseas imported COVID-19 cases shortened, and booster COVID-19 vaccination facilitated the alleviation of severity of clinical symptoms. There is a long-term risk of overseas importation of COVID-19 in Zhejiang Province, and the containment of imported COVID-19 requires to be sustainably implemented among entry personnel.

Objective: To investigate the characteristics of public health emergencies in Zhejiang Province in 2023, so as to provide the reference for public health risk management. Methods: Data of public health emergencies and related information in Zhejiang Province from January 1 to December 31, 2023 was collected through Emergency Public Reporting System of Chinese Disease Prevention and Control Information System. Attack rates, disease types, distribution of time and places, and responses were descriptively analyzed. Results: A total of 718 public health emergencies were reported in 2023 in Zhejiang Province, and all were infectious disease events. There were 27 128 reported cases and 3 deaths, with an attack rate of 3.22%. The top five infectious diseases with the highest number of reported events were influenza, norovirus infection, monkeypox, varicella and hand, foot and mouth disease, accounting for 95.54% of total reported events. There were 355 public health emergencies with less than 30 cases each, accounting for 49.44%. The reported emergencies peaked from February to March (186 events, 25.91%) and from November to December (327 events, 45.54%), and mainly occurred in schools and preschool institutions (651 events, 90.67%). The median responding time, reporting time and duration of emergencies were 6.50 (interquartile range, 10.84) h, 0.53 (interquartile range, 0.63) h and 7.24 (interquartile range, 11.71) d, respectively. Conclusion Public health emergencies in Zhejiang Province in 2023 were mainly caused by influenza and norovirus infection, with February, March, November and December being the peak reporting periods, and schools and preschool institutions being the main places where these events occurred.

Objective: To investigate epidemiological characteristics of notifiable infectious diseases in Zhejiang Province in 2023, so as to provide the evidence for strengthening prevention and control of infectious diseases. Methods: Data pertaining to notifiable infectious diseases reported in Zhejiang Province in 2023 were retrieved from the Infectious Disease Surveillance System of Chinese Disease Prevention and Control Information System. The incidence and mortality were analyzed according to the classification of notifiable infectious diseases and transmission routes, and epidemiological characteristics of infectious diseases were descriptively analyzed. Results: Thirty types of notifiable infectious diseases with 2 955 699 cases and 427 deaths were reported in Zhejiang Province in 2023, with a reported incidence rate of 4 493.93/105 and a reported mortality rate of 0.649 2/105. A total of 679 notifiable infectious disease emergencies were reported, with 26 514 cases and 1 case death (rabies). The emergencies mainly occurred in schools and preschool institutions, with 621 cases accounting for 91.46%. There were 1 case of cholera reported in class A notifiable infectious diseases and no death, 22 types of class B notifiable infectious diseases, with a reported incidence rate of 552.46/105 and a reported mortality rate of 0.644 7/105, and 8 types of class C notifiable infectious diseases, with a reported incidence rate of 3 941.48/105 and a reported mortality rate of 0.004 6/105. The incidence rates of respiratory, intestinal, blood-borne and sexually transmitted, natural and insect-borne infectious diseases were 4 028.67/105, 381.59/105, 81.15/105 and 1.35/105, respectively, according to transmission routes. Influenza (3 561.78/105) and COVID-19 (423.77/105) reported the highest incidence, and AIDS (0.477 4/105) and tuberculosis (0.130 8/105) reported the highest mortality. Conclusion The incidence rates of respiratory and intestinal infectious diseases were high in Zhejiang Province in 2023, and schools and preschool institutions were the main places of diseases occurred.

Objective: To analyze the disease burden of acute gastrointestinal illness (AGI) caused by non-typhoidal Salmonella and Vibrio Parahaemolyticus in Zhejiang Province, so as to provide the reference for the prevention and control of foodborne diseases. Methods: The detection rates of non-typhoidal Salmonella and Vibrio parahaemolyticus in 2022 were collected through the Zhejiang Foodborne Disease Outbreak Surveillance System. The number of cases, incidence and hospitalizations of AGI caused by non-typhoidal Salmonella and Vibrio parahaemolyticus were calculated. Disability-adjusted life years (DALY) were used to analyze the disease burden of AGI caused by non-typhoidal Salmonella and Vibrio parahaemolyticus among different age groups. Results: The number of AGI cases caused by non-typhoidal Salmonella in Zhejiang Province in 2022 was 889 500 person-times, the incidence rate was 1 352.42/105, the number of hospital visits was 328 900 person-times, the DALY was 972.69 (95%CI: 771.68-1 164.16) person-years, and the DALY rate was 1.48 (95%CI: 1.17-1.77) /105. The incidence rate and DALY rate were highest in the children aged under 5 years, reaching 3 989.51/105 and 13.93 (95%CI: 8.67-18.42) /105, respectively. The number of AGI cases caused by Vibrio parahaemolyticus in Zhejiang Province was 639 400 person-times, the incidence rate of 972.16/105,the number of hospital visits was 166 800 person-times, the DALY was 509.30 (95%CI: 411.75-699.62) person-years, and the DALY rate was 0.78 (95%CI: 0.63-1.06)/105. The incidence rate and DALY rate were highest in the residents aged 45 to <65 years, reaching 1 383.55/105 and 1.27 (95%CI: 1.14-1.96)/105, respectively. Conclusions The incidence and DALY of AGI caused by non-typhoidal Salmonella were relatively high in Zhejiang Province. The AGI caused by non-typhoidal Salmonella in the children under 5 years and the AGI caused by Vibrio parahaemolyticus in the residents aged 45 to <65 years need to be monitored with priority.

Objeetive: To evaluate the imported risk of COVID-19 cases from aboard to Zhejiang Province,so as to provide reference for control strategies. Methods: The epidemic data of COVID-19 in 9 foreign countries（US,UK,Italy,etc.）and Zhejiang Province were collected,as well as the number of entry persons. The imported risk values of COVID-19 cases to 90 counties（cities or districts）of Zhejiang Province and from the 9 countries during March 7th and 30th were calculated and normalized to the imported risk indexes. The imported risk indexes were classified into five levels from high to low according to percentiles. The imported risk of 90 counties（cities or districts）,the developing trend and the source were analyzed. Results : A total of 39 confirmed cases and 24 asymptomatic cases were imported to Zhejiang Province untill March 30th. There were 10,13,22,21 and 24 counties（cities or districts）with high,medium high,medium,medium low and low imported risk,respectively. Qingtian had the highest imported risk（0.43）,followed by Ruian（0.32）and Wencheng（0.29）. The imported risks in 80（88.89%）counties（cities or districts）showed increased trend. The highest imported risk came from Italy（0.51）,followed by US（0.14）and Spain（0.11）. The imported risk in Wenzhou and Lishui mainly came from Italy and Spain,while that in the other areas mainly came from US,Germany and UK. Conclusions The risk of imported COVID-19 cases from aboard to Zhejiang Province showed an upward trend since March. The areas at high and medium high risk lay in southeast Zhejiang and the downtown of Hangzhou. The source of imported risk were maimly from Italy,US and Spain,but varied in counties.

Objective To understand the distribution of the severe fever with thrombocytopenia syndrome (SFTS) in Zhejiang province,and predict the incidence and the probability of SFTS outbreak.Methods Based on the cases of SFTS from 2011-2015,software ArcGIS 10.0 was used to analyze the spatial distribution,Moran's I and Getis-Ord Gi were used to analyze the spatial autocorrelation.The incidence trend was explored by trend surface analysis,and the prediction was made by Kriging interpolation.Results The incidence of SFTS increased and the distribution expanded in Zhejiang from 2011 to 2015,the seasonal and the demographic characteristics of SFTS were similar to the previous research;there were regional clustering of the cases (P＜0.001);a downward trend was observed from northeast to southwest in terms of incidence of SFTS;the second-order disjunctive Kriging interpolation based on circular model and the indicator Kriging interpolation based on exponential model had higher prediction accuracy,the probabilities of outbreak in Anji,Daishan and Tiantai were high,the prediction deviation of inland was less than that of edge area.Conclusion The prediction of SFTS by Kriging interpolation had high accuracy,the incidence of SFTS was higher and the distribution of SFTS was larger than the results of surveillance,the risk areas for epidemic were Anji,Daishan,Ninghai,Tiantai,Sanmen and Linhai.

Objective To analyze the epidemiological characteristics of imported malaria in Zhejiang Province from 2007 to 2016,in order to provide a scientific basis for further improving the level of imported malaria control.Methods Data on malaria cases in Zhejiang Province from 2007 to 2016 were collected through the China Information System for Disease Control and Prevention (CISDCP).Descriptive epidemiological method was used to analyze the epidemiological characteristics of the imported malaria cases reported (including time distribution,regional distribution and population distribution).Results A total of 1 298 imported malaria cases were reported in Zhejiang Province from 2007 to 2016,including 988 falciparum malaria cases,237 vivax malaria cases,45 ovale malaria cases,12 quartan malaria cases,7 mixed infection and 9 unclassified cases.Most cases were 20 to 49 years old,accounting for 82.43％ (1 070/1 298) of the total and the male to female ratio of the cases was 9.30:1.00.The main groups of imported malaria cases were labor export staff,accounted for 46.92％ (609/1 298);followed by business services,accounted for 38.91％ (505/1 298).The cases mainly distributed in Jinhua,Hangzhou,Wenzhou,Lishui and Taizhou,which accounted for 75.96％ (986/1 298) of the total.Totally 87.21％ (1 132/1 298) of cases were imported from Africa,and 12.63％ (164/1 298) were from Asian.Imported malaria cases were reported every month in the whole year without seasonal peaks.Conclusion Imported malaria cases in Zhejiang Province are given priority to with labor export and business services,so it is necessary to strengthen monitoring,diagnosis,and treatment of imported malaria cases among overseas workers and businessmen from the malaria prevalent areas in Africa and Asian countries.