[Risk assessment for emergency events of infectious disease in outlying areas of large-scale activities].

OBJECTIVE: To identify and assess the potential public health risks of emergency events of infectious disease in the surrounding areas of Hangzhou during the 11th G20 summit, and to assess their impacts on the G20 summit. METHODS: The surrounding cities of Hangzhou included Ningbo, Wenzhou, Jiaxing, Huzhou, Shaoxing, Jinhua, Quzhou, Zhoushan, Taizhou and Lishui. Background information on infectious diseases in Zhejiang province was collected, and the brainstorming and expert consultation methods were used to identify the risks. The local risks and the impact of local risks on the G20 summit were assessed. RESULTS: The criteria for public health risk was first established. Through the assessments,a total of 27 kinds of infectious diseases in 4 types of public health risks were identified. The impact of these risks on Hangzhou G20 summit was divided into 1 item of high-risk, 12 items of medium risk and 14 items of low risk.According to the results of risk assessment, the recommendations for risk management of respiratory infectious diseases, intestinal infectious diseases, imported infectious diseases like Middle East respiratory syndrome and other infectious diseases were made. With risk management, Middle East respiratory syndrome was not occurred during the G20 summit, and the epidemic situation of other infectious diseases with middle or low risks was almost the same with that of past years. CONCLUSIONS: sThe public health risks of Hangzhou G20 summit from sudden infectious diseases in outlying areas are mainly medium and low risks. The recommendations on risk management provide a basis for reducing the adverse consequences of public health risks in the event of an outbreak of infectious diseases, avoiding the impact of various risk factors in the outlying areas on G20 summit.

[The negative psychology for the public in Zhejiang province during the epidemic of human H7N9 avian influenza].

OBJECTIVE: To evaluate the cognition and emotional response of the public in Zhejiang province during the epidemic of human H7N9 avian influenza and provide scientific support for group psychological intervention under public health emergency. METHODS: 57 communities in 19 counties from Hangzhou, Jiaxing and Lishui district of Zhejiang province were selected as survey sites using stratified clustered sampling method from March, 2013 to April, 2014. 2 319 ordinary civilians were chosen using convenience sampling method and 390 individuals who had close contact history with H7N9 avian influenza patients, 109 family members of patients and 281 medical workers, were selected using census method. The inclusion criteria for subjects were: subjects aged over 10 years; could complete the questionnaire independently or with the help of the investigators. A total of 2 709 subjects were surveyed by avian influenza risk perception and response questionnaire, negative emotion questionnaire was also used to see their cognition and negative emotion related to the disease. Spearman correlation analysis was used to analyze the interrelationship between public risk perception, response and negative emotions. RESULTS: 95.10% (2 576)of the subjects have sensed the risk of epidemic and 91.00% (2 465) of the subjects have taken preventive measures in 2 709 subjects. The positive rate for depression, neurasthenia, fear, anxiety and hypochondriasis were 36.40% (986) , 37.21% (1 008) , 79.70% (2 159) , 33.41% (905) , 27.69% (750) respectively (χ(2)=1 935.89, P<0.001) ;the P(50)(P(25)-P(75)) of the depression scores of patients' family members, medical workers and the general public were 0.50 (0.00-0.83), 0.17 (0.00-0.67), 0.17 (0.00-0.50) (H= 7.27, P=0.03) ; the neurasthenia scores were 0.20 (0.00-0.60), 0.2 (0.00-0.40), 0.00 (0.00-0.20) (H= 64.74, P<0.001) ; fear scores were 0.83 (0.33-1.17), 0.33 (0.17-0.67), 0.33 (0.17-0.83) (H=30.03, P< 0.001) ; anxiety scores were 0.17(0.00-0.50), 0.00(0.00-0.33), 0.00(0.00-0.17) (H=51.82, P<0.001). The neurasthenia, fear, anxiety scores (P(50)(P(25)-P(75))) for females among the public were 0.00(0.00-0.20), 0.50(0.17-0.83), 0.00(0.00-0.17), which were higher than those of male's (0.00(0.00-0.20), 0.33(0.00-0.67), 0.00(0.00-0.17)) (χ(2) values were 5.26, 27.52, 8.29, P<0.05); Among medical staff, the depression, neurasthenia, fear, anxiety and hypochondriasis scores for females were 0.33(0.00-0.67), 0.20(0.00-0.40), 0.50(0.17-0.83), 0.00(0.00-0.33), 0.00(0.00-0.50) respectively, which were higher than those of males'(0.00(0.00-0.50), 0.00(0.00-0.40), 0.33(0.17-0.50), 0.00(0.00-0.17), 0.00(0.00-0.00))(χ(2) values were 7.22, 7.97, 14.46, 4.93, 5.22, P<0.05); for the family members of the patients who were in poor mental conditions when doing self-assessment, their depression and neurasthenia scores were 0.50(0.08-0.96), 0.30(0.00-0.55), which were higher than those of people in good mental conditions (0.17(0.00-0.83), 0.20(0.00-0.60)) (χ(2) values were 12.95, 11.20, P<0.05). Spearman correlation analysis showed that the subjects' risk perception level was positively correlated with depression, neurasthenia, fear, and hypochondriasis, with the correlation coefficients 0.07, 0.07, 0.08, 0.04, respectively (P<0.05) ; the subjects' risk response level was also positively related with depression, neurasthenia, fear, anxiety and hypochondriasis, and the correlation coefficients were 0.09, 0.09, 0.12, 0.05, 0.04, respectively (P<0.05). CONCLUSION: The general public was highly concerned about the epidemic of H7N9 avian influenza and developed certain levels of negative emotions. The female, equal or over 60 years old, those with poor educational level, agricultural related occupation and poor physical and psychology health were risk factors of disease related negative emotions. The subject's risk perception and response level was positively related with depression, neurasthenia, fear and hypochondriasis.

Bacteriostatic effect of Ag@TiO2-Poly(p-dioxanone)-coated gauzes in vitro and in vivo on otitis media pathogens.

The application of packing agents affects the final surgical outcomes in treating otitis media (OM) and introduces the risk of infection. To decrease the infectious risks of packing agents and even introduce positive bacteriostatic functions, a kind of PPDO-grafted Ag-incorporated TiO2 nanoparticles (Ag@TiO2-PPDO NP)-coated gauzes were prepared by a solution immersion method. Morphologies and in vitro Ag+ releasing of Ag@TiO2-PPDO NP coated gauzes were determined by scanning electron microscope (SEM) and inductively coupled plasma-mass spectrum (ICP-Ms). Ag@TiO2-PPDO NP could respond to visible light, which might make Ag@TiO2-PPDO NP inhibit the proliferation of bacteria continually and positively with irradiation of visible light. Then the bacteriostatic effects of these gauzes on OM pathogens were investigated in vitro and in vivo. These gauzes could inhibit the proliferation of pathogenic Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae) in vitro and rat subcutaneous infection models. Specifically, the bacteriostatic effect of these gauzes on S. aureus and S. pneumoniae could be enhanced with irradiation by visible light in vitro. Further, the rat external auditory canal infection model verified the enhanced bacteriostatic effect of Ag@TiO2-PPDO-coated gauzes on S. aureus with irradiation by visible light. The Ag@TiO2-PPDO-coated gauzes are promising for packing materials after OM surgery and could reduce postoperative antibiotic requirements.

A Bayesian classification model for discriminating common infectious diseases in Zhejiang province, China.

To develop a classification model for accurately discriminating common infectious diseases in Zhejiang province, China.Symptoms and signs, abnormal lab test results, epidemiological features, as well as the incidence rates were treated as predictors, and were collected from the published literature and a national surveillance system of infectious disease. A classification model was established using naïve Bayesian classifier. Dataset from historical outbreaks was applied for model validation, while sensitivity, specificity, accuracy, area under the receiver operating characteristic curve (AUC) and M-index were presented.A total of 146 predictors were included in the classification model, for discriminating 25 common infectious diseases. The sensitivity ranged from 44.44% for hepatitis E to 96.67% for measles. The specificity varied from 96.36% for dengue fever to 100% for 5 diseases. The median of total accuracy was 97.41% (range: 93.85%-99.04%). The AUCs exceeded 0.98 in 11 of 12 diseases, except in dengue fever (0.613). The M-index was 0.960 (95%CI 0.941-0.978).A novel classification model was constructed based on Bayesian approach to discriminate common infectious diseases in Zhejiang province, China. After entering symptoms and signs, abnormal lab test results, epidemiological features and city of disease origin, an output list of possible diseases ranked according to the calculated probabilities can be provided. The discrimination performance was reasonably good, making it useful in epidemiological applications.

Assessing cyber-user awareness of an emerging infectious disease: evidence from human infections with avian influenza A H7N9 in Zhejiang, China.

OBJECTIVES: The aim of this study was to assess cyber-user awareness of human infections with avian influenza A H7N9 in Zhejiang, China. METHODS: Daily Baidu index values were compared for different keywords, different periods (epidemic and non-epidemic), different levels of epidemic publicity (whether new cases were publicized), and different cities (divided into high, medium, low, and zero groups according to the number of cases). Furthermore, the correlation between the daily Baidu index values and the daily number of new cases was analyzed. RESULTS: Three epidemic periods (periods A/C/E) and three non-epidemic periods (periods B/D/F) were identified from April 2013 to May 2015 according to the curves of daily new cases. Each epidemic period was followed by a non-epidemic period. Baidu index values using 'H7N9' as a keyword were higher than the values using the keyword '' (avian influenza in Chinese) in earlier periods, but the situation reversed in later periods. Index values for 'H7N9' in the epidemic periods were higher than in the non-epidemic periods. In the first epidemic period (period A), the Baidu index values for 'H7N9' showed no difference between the different levels of epidemic publicity and had no correlation with the daily number of new cases. The index values in cities without reported cases showed no difference from the values recorded in the medium and low groups. However, a difference and a correlation were found in a later epidemic period. CONCLUSIONS: The Baidu index would be a useful tool for assessing cyber-user awareness of an emerging infectious disease.

Food-borne disease outbreak of diarrhetic shellfish poisoning due to toxic mussel consumption: the first recorded outbreak in china.

OBJECTIVES: This investigation was undertaken in response to an outbreak of suspected shellfish poisoning in Zhejiang Province, China. The objectives of this project were to confirm the outbreak and to identify the aetiology, source and mode of transmission. METHODS: A probable case was defined as an individual with diarrhea (≥3 times/day) plus at least one of the following symptoms: fever (≥37.5°C), vomiting, or abdominal pain after consuming seafood between May 23(rd) and May 28(th), 2011. Using a case-control study design, we compared exposures to suspected seafood items and cooking methods between 61 probable cases and 61 controls. RESULTS: Over 220 suspected or probable cases of diarrhetic shellfish poisoning (DSP) were identified (incidence of 18 cases per 100,000). The case control study revealed that 100% of cases and 18% of controls had eaten mussels during the exposure period (OR = ∞, χ(2) = 84.72,P = 0.000). The number of mussels consumed was related to DSP risk (P = 0.004, χ2 test for trend). Consumption of other seafood items was not associated with disease. The frequency of diarrhea and vomiting were positively correlated with the number of mussels consumed (r = 0.424 and r = 0.562, respectively). The frequency of vomiting and the incubation period were significantly correlated with the total time the mussels were boiled (r = 0.594 and r = -0.336, respectively). Mussels from 3 food markets and one family contained Okadaic acid (OA) and Dinophysistoxin-1 (DTX-1). CONCLUSIONS: This outbreak was attributed to the consumption of mussels contaminated by DSP-toxins (OA and DTX-1) which are produced by different species of dinoflagellates (toxic microalgae) from the genus Dinophysis or Prorocentrum. Suspension of mussel sales and early public announcements were highly effective in controlling the outbreak, although oversight of seafood quality should be a priority to prevent future contamination and outbreaks.

[A three-year follow-up study on sera specific antibody in severe acute respiratory syndrome cases after the onset of illness].

OBJECTIVE: To study the variation of specific antibody among convalescent of severe acute respiratory syndrome (SARS) patients through a three-year program. METHODS: Sera samples were collected from SARS cases in the 5th, 20th and 35th month after onset of the illness. The SARS-CoV specific antibody was detected for all of them by ELISA and neutralized test simultaneously. The titer of neutralizing antibodies was calculated using Reed-Muench method, and the comparison between different time groups was analyzed regarding the variance of data on repeated measures after logarithm conversion. RESULTS: 13, 17 and 13 sera samples were collected in the 5th, 20th and 35th month after onset. Results showed that despite the fact that the positive rates of ELISA antibody were 100%, 82.4% and 84.6% respectively,the neutralizing antibody was still positive for all the samples. The average neutralizing antibody titers were 1:43 (1:16-1:203), 1:36 (1:17-1:59) and 1:21 (1:10-1:39) on the 5th, 20th and 35th month after onset, and the differences were statistically significant (F = 60.419, P < 0.001). On the 35th month after the onset, 30.8% (4/13) of the patients were still having the neutralizing antibody level of above 1:36, but the neutralizing antibody level in another 30.8% (4/13) of the patients had decreased to as low as 1:10, when the cut-off level was set as 1:8. CONCLUSION: Results of the study indicated that the neutralizing antibody of SARS cases could last for at least three years, but the sera specific antibody in SARS cases decreased gradually when time went by. However, neutralizing antibody in some of the cases decreased to a lower level on the 35th month. Further follow-up study was worthwhile to observe the long-lasting profile of antibody existence on SARS cases.

[Study on a 10-year protective effects of vaccination against hemorrhagic fever with renal syndrome].

OBJECTIVE: To evaluate the epidemiological and serological efficacy after 10 years of vaccination against hemorrhagic fever with renal syndrome (HFRS) vaccines in Zhejiang province. METHODS: One county was randomly chosen as the research unit with all the healthy people between 16 and 60 years old were equally divided into study and control groups. The study group was vaccinated. Immunofluorescent antibody assay was used to test specific IgG antibody and Mcro-CPE method was used to test the titer of neutralizing antibody. RESULTS: Two weeks after the full-course immunization, the seroconversion rate became 100% (67/67, with 95% CI as 96.3%-100%) by immunofluorescent antibody test (IgG) and 44.4% (8/18 with 95% CI as 22.0%-69.0%) by neutralization test with GMT titers as 72.1 and 4.6 respectively. Booster immunization was provided one year later. Time span as two weeks prior to, one year, one and half years, two years, three years and five years after booster immunization, the rates of seroconversion on immunofluorescent antibody using IFAT method, were 28.6%, 83.3%, 75.0%, 53.1%, 22.6%, 10.0% and 55.0% respectively, and rates of seroconversion of neutralizing antibody by Mcro-CPE method were 14.8%, 55.6%, 35.0%, 31.3%, 26.0%, 10.0% and 50.0% respectively. Nine years after the reinforcement, the rates of seroconversion of immunofluorescent antibody by IFAT method was only 7.1%. The vaccinated group had no patient seen but the control group appeared 34 patients including 3 deaths. According to the ten-year observation, the vaccine seemed effective with the protection rate in population reached 100%. CONCLUSION: HFRS vaccine was effective on epidemiological, social and economical efficacy.