Design and implementation of Geographical Information System on prevention and control of cholera / 中华流行病学杂志

To build the Geographical Information System (GIS) database for prevention and control of cholera programs as well as using management analysis and function demonstration to show the spatial attribute of cholera.Data from case reporting system regarding diarrhoea,vibrio cholerae,serotypes of vibrio cholerae at the surveillance spots and seafoods,as well as surveillance data on ambient environment and climate were collected.All the data were imported to system database to show the incidence of vibrio cholerae in different provinces,regions and counties to supoport the spatial analysis through the spatial analysis of GIS.The epidemic trends of cholera,seasonal characteristies of the cholera and the variation of the vibrio cholerae with times were better understood.Information on hotspots,regions and time of epidemics was collected,and helpful in providing risk prediction on the incidence of vibrio cholerae.The exploitation of the software can predict and simulate the spatio-temporal risks,so as to provide guidance for the prevention and control of the disease.

Study on the spread of influenza A (H1N1) under community based simulation model / 中华流行病学杂志

A simulation experiment was carried out by applying the simulation model to spread of influenza A (H1N1) in communities with different population density. Population at the community-level was divided into susceptible, infected and recovered ones, according to the susceptive-infective-removal (SIR) model, and the age structure of the population was set on the basis of data from the Fifth Population Census. Contact and moving of the individuals were based on the Network Random Contact Model and the mortality and infection mode were established in line with the influenza A (H 1N 1) medical description. The results of an example analysis showed that the infection rate was closely related to the density of the community-based population while the rate on early infection grew rapidly. Influenza A (H1N1) seemed more likely to break out in the community with population density of over 50/hm2. Comparative tests showed that vaccination could effectively restrain the spread of influenza A (H1N1) at the community level. Conclusion Population density,and the coverage of influenza vaccination were risk factors for influenza A (H1N1) epidemics.Results of the experiment showed of value, for prevention and vaccination on this topic.

Spatiotemporal characteristics of seasonal influenza in mainland China / 中华流行病学杂志

Objective To study the spatiotemporal distribution and seasonal characteristics of influenza and to explore its transmission patterns, in the mainland of China. Methods Spatiotemporal cluster methods and spatial trend surface methods were used to analyze the influenza surveillance data. Results There were a summer peak in the south from June to August (RRpsediatric=1.31, P<0.01; RRmternel=1.74, P<0.01) and a winter peak from December to January (RRpsediatric=1.45, P<0.01; RRmternel=1.45, P<0.01) in the northern part of the country, during every epidemic season. Influenza virus in mainland China seemed to spread from the southern to the northern parts of the country, in a progressing way. Conclusion In the southern part of the country, it is more important to take prevention and control measurements on influenza from June to August but for the northern part, the key period is from December to January. It is more important to timely identify the variation of the influenza virus, in the southern part of the country.

Epidemiological characteristics of 420 influenza A (H1N1) cases confirmed in the early stage of the epidemic in mainland China / 中华流行病学杂志

Objective To describe the epidemical characteristics of A (H1N1) influenza identified in the early stage (from May 11 to June 22, 2009) of the epidemic, in mainland China. Methods Epidemical characteristics of 420 confirmed A (H1N1) influenza cases reported from May 11 to June 22, 2009 were analyzed descriptively, including the distribution of age, sex, source of infection, main symptoms and incubation period. Results A total of 77.8% early cases in mainland China were imported from other countries. Three countries including America, Canada and Australia were attributed to 90% of the imported cases. Most of the cases were from 6 months to 73 years old, with 94% of them under 50 years. Most of the symptoms would include fever (81%), cough (40%) and sore throat (35%). The mean incubation period of second-generation cases was 4.3 (4.2±1.5) days. Conclusion Imported cases dominated the total cases in the early stage of the epidemic had similar gender distribution of those from exporting countries. Fever, cough and sore throat were the three main symptoms manifested in influenza cases. 2.5±1.9(1-11)days was found in imported cases between the day of off-board and the onset of symptoms. The incubation period was 4.3±1.7 (1-8) days among the secondary cases.

Pattern on the spread of novel influenza A(H1N1) and quantitative assessment of containment in mainland China / 中华流行病学杂志

Objective To study the epidemic tendency of emerging influenza A (H1N1) in mainland China, and to explore the different patterns of spread on the disease under the following contexts: (1) To stop the temperature screening program at the border areas of the country; (2)To stop measures of prevention and control on those identified cases and their close contacts; (3) To strengthen programs for the foreign immigrants on 'home quarantine'. Methods Under relevant parameters and information on the transmission link from different reference data, the patterns of influenza spread were simulated by Monte Carlo method. Results The temperature screening on border could inhibit the transmission of influenza A (H1N1) to some extent, so that after 3 months the cumulative number of cases will be reduced by 21.5% (1718 cases) and transmission speed of influenza A (H1N1) in mainland China will be delayed by about 4 days. Furthermore, taking positive measures of prevention and control could efficiently slow down the epidemic, so that after 3 months the cumulative number of cases will be reduced by 93.4%(about 90 thousand cases) and it would be delayed by about 15 days if influenza A (H1N1) spreads to the whole country. In addition, if the immigrants were able to practise quarantine measures consciously by themselves at home the effect of prevention and control against influenza A(H1N1) would be more significant. If 30%, 60% and 90% of immigrants would take quarantine measures home consciously, after 3 months the cumulative number of cases will be reduced by about 15% (about 940 cases), 34% (about 2230 cases) and 64% (about 4180 cases), respectively. Also, influenza A (H1N1) spreads to the whole country will be delayed by about 4 days, 10 days and 25 days, respectively. It is difficult to curb fully the development of the epidemic by taking existing control measures, and influenza A (H1N1) may spread to almost all provinces after about 3 months. Conclusion The effects of existing prevention and control measures were objectively assessed and the results showed the necessity and effectiveness of these measures against the transmission of influenza A (H1N1) , in the mainland of China.