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.

Association between the incidence of typhoid and paratyphoid fever and meteorological variables in Guizhou, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Typhoid/paratyphoid fever (TPF) is endemic in Guizhou. We conducted wavelet analysis and Spearman's rank correlation analysis to explore the impact of meteorological variations on TPF infection in Guizhou, in an attempt to assess the risk factors associated with TPF epidemics.</p><p><b>METHODS</b>We examined the association between TPF incidence in Guizhou and temperature, precipitation and relative humidity using 24 years of data from 1984 to 2007. Periodicities of TPF incidence and the impact of climate factors on the TPF were detected by Spearman's rank correlation and wavelet analysis,</p><p><b>RESULTS</b>Temperature and precipitation with a 1-month lag were positively correlated with the monthly incidence of TPF. The multiyear incidence pattern of TPF in Guizhou was explicitly periodic. Moreover, the association and driving effect of precipitation on TPF were observed, and the results showed that the incidence of TPF in Guizhou had a closer correlation with precipitation than with temperature.</p><p><b>CONCLUSIONS</b>Safe water supply is the key issue for TPF control in Guizhou. Moreover, climate variation might impact the enteric infections, which may inform policy assessment for TPF control in Guizhou.</p>

Typhoid and paratyphoid fever in Yunnan province: distributional patterns and the related meteorological factors / 中华流行病学杂志

Objective To characterize the spatial distribution of typhoid and paratyphoid fever(TPF)in Yunnan province, China and to determine the effectiveness of meteorological factors on the epidemics of TPE Methods Data of reported TPF cases in Yunnan province(2001 -2007)from the China Information System for Diseases Control and Prevention was applied to GIS-based spatial analyses to detect their spatial distribution and clustering of TPF incidence at the county level.Panel data analysis was used to identify the relationships between the TPF incidence and meteorological factors including monthly average temperature, monthly cumulative precipitation and monthly average relative humidity. Results During the study period, the average incidence of TPF in Yunnan province was 23.11/100 000, with majority of the TPF cases emerged in summer and autumn. Although widely distributed, two TPF clusters were detected in Yunnan province based on the spatial analysis:one area around Yuxi city with the average annual incidence as 207.45/100 000 and another at the junctions of Yunnan province with Burma and Laos. Based on results from panel data analysis, the incidence of TFP was shown to be associated with meteorological factors such as temperature,precipitation, relative humidity and one month lag of temperature increase [10 ℃ increase in the monthly average temperature:IRR=1.30(95%CI: 1.24-1.36);10% increase in monthly average relative humidity:IRR= 1.07(95%CI: 1.05-1.09); 100 mm rise in monthly cumulative precipitation:IRR=1.02(95%CI: 1.00-1.03); and 10 ℃ average temperature increase, the last month: IRR=1.73(95%CI: 1.64-1.82)]. Conclusion Areas with high TPF incidence were detected in this study,which indicated the key areas for TPF control in Yunnan province. Meteorological factors such as temperature, precipitation and humidity played a role in the incidence of TPF.

Complete sequence of the M segment of Amur virus in rodent from China / 中华流行病学杂志

Objective To study the complete sequence of M segment of Amur virus in rodents and to explore their molecular characteristics. Methods Complete M segment of Amur virus in rodent from China was amplified by RT-PCR. The purified PCR product was cloned into pGEM-T Easy vector and then sequenced. Phylogenetic analysis on multiple nucleotide sequences was performed with the Tree PUZZLE and DNAStar software. Results The full-length of its M gene comprised of 3615 nucleotides with one open reading frame (ORF) including 3408 nucleotides and encoding a protein which comprised 1135 amino acids. The ORF was located at bases 41 to 3448. The phylogenetic analysis of JilinAP06 with other hantaviruses revealed that the complete sequence of M segment of JilinAP06 strain was closely related to those Amur viruses such as B78 strain, Liu strain and H5 strain were all from the patients. The complete sequence of M segment of JilinAP06 had only 79.5% identities with the nucleotide sequence of HTNV strain 76-118. Conclusion The complete sequence on M segment of Amur virus in rodent was first time identified in this country.

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.

Study on the determinants regarding malaria epidemics in Anhui province during 2004-2006 / 中华流行病学杂志

Objective To analyze the determinants of malaria in Anhui province during the year of 2004-2006.Methods A GIS-based database of malaria at the township scale of Anhui province was established,using remote sensing and spatial analysis technologies.Methods on statistical analysis,principal component analysis combined with logistic regression analysis were synthetically used to analyze the association between malaria and environmental factors.Results Malaria epidemics in Anhui province during 2004-2006 mainly occurred in the northern districts of Huai River,and the epidemics had become more serious yearly.The determinants of malaria at the township scale mainly included factors as temperature,rainfall,normalized difference vegetable index and elevation.If the lowest temperature in a year,which appeared the fourth principal component of the temperature index series,increased by one unit,the probability of incidence of malaria would decrease by 33%.If the total annual rainfall,which was the first principal component of the rainfall index series,increased by one unit,the probability would decrease by 27%.If the elevation increased by 10 meters,the probability would decrease by 2%.However,the relationship between Normalized Difference Vegetable Index (NDVI) and the probability of incidence of malaria was different.If the NDVI had a one unit increase,the probability would increase 3.28 times.Conclusion The northern districts of Huai River during 2004-2006 appeared to be a new spatio-temporal cluster when reemergence of malaria epidemics had occurred in Auhui province since 2000.Terrain and physiognomy,nature and circumstances factors,such as temperature and rainfall had affected the incidence rates of malaria.Our research data from Auhui province would provide some important references to the discovery of main reasons on the reemergence of malaria epidemics since 2000,especially in the central geographic areas of China.

Spatial epidemiological study on malaria epidemics in Hainan province / 中华流行病学杂志

Objective To better understand the characteristics of spatial distribution of malaria epidemics in Hainan province and to explore the relationship between malaria epidemics and environmental factors, as well to develop prediction model on malaria epidemics. Methods Data on Malaria and meteorological factors were collected in all 19 counties in Hainan province from May to Oct. , 2000, and the proportion of land use types of these counties in this period were extracted from digital map of land use in Hainan province. Land surface temperatures (LST)were extracted from MODIS images and elevations of these counties were extracted from DEM of Hainan province. The coefficients of correlation of malaria incidences and these environmental factors were then calculated with SPSS 13.0, and negative binomial regression analysis were done using SAS 9.0. Results The incidence of malaria showed (1) positive correlations to elevation, proportion of forest land area and grassland area; (2) negative correlations to the proportion of cultivated area, urban and rural residents and to industrial enterprise area, LST; (3) no correlations to meteorological factors, proportion of water area, and unemployed land area. The prediction model of malaria which came from negative binomial regression analysis was: Ⅰ(monthly, unit:1/1 000 000) = exp( - 1. 672 - 0. 399 × LST). Conclusion Spatial distribution of malaria epidemics was associated with some environmental factors, and prediction model of malaria epidemic could be developed with indexes which extracted from satellite remote sensing images.

Studies on the spatial distribution and environmental factors of highly pathogenic avian influenza in Mainland China, using geographic information system technology / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the spatial distribution of highly pathogenic avian influenza (HPAI) and to explore environmental factors associated with HPAI using geographic information system (GIS) techniques in Mainland China.</p><p><b>METHODS</b>Databases were set up using the information of HPAI during epidemics in 2004, and linked to digital maps at provincial and county administrative layers in the country through the ArcGIS 8.3 software. Spatial cluster analyses, spatial statistics analyses and tracking analyses on epidemic situation of HPAI were implemented. Environmental factors associated with HPAI were also analyzed on data related to weather, vegetation and migratory birds etc.</p><p><b>RESULTS</b>Findings from spatial cluster analyses showed that high incidence area was centralized in 113.261 degrees ordm; east longitude and 23. 119 degrees ordm; north latitude with a radius of 1090.52 kilometers (relative risk= 2.646, P value= 0.001). Spatial statistical analyses showed that HPAI took place mainly in capital cities of provinces and surrounding areas as well as in the circumference areas of arterial rivers, lakes and seacoasts. Results also showed that HPAI occurrences were associated with low air temperature, high relative humidity and high air pressure as well as with east & central migration routes of migratory birds. The average normalized difference vegetation index was 0.36 +/- 0.11 in epidemic areas of HPAI.</p><p><b>CONCLUSION</b>HPAI was unrandomly distributed and geographically clustered in China.</p>

A case-control study on the risk factors of severe acute respiratory syndromes among health care workers / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the factors in relation to severe acute respiratory syndromes (SARS) among health care workers and to develop related protective measures.</p><p><b>METHODS</b>Case-control study was applied. A standardized questionnaire was used to collect SARS related information for health care workers who had contacted or treated SARS patients. Univariate analysis was conducted using SPSS 10.0 software package and multivariate logistic regression analysis was conducted using SAS 6.12.</p><p><b>RESULTS</b>Twenty-seven of the 49 factors under study were significantly associated with SARS infection, in which 22 factors were protective, and the other 5 were risk factors. 27 factors were included for multivariate logistic regression analysis. Results showed that six factors as wearing eye glasses, wearing protection gowns, exposure to secrets/mode of contact with SARS patients, types of mask and the working years atc, remained significant association with hospital infection of SARS.</p><p><b>CONCLUSION</b>SARS infection in heath care workers was related to many factors during the process of diagnoses and/or treatment. It is recommended that adequate masks, eye-protection and protective gowns should be adopted for heath care workers during the process of clinical diagnoses and treatment of SARS patients.</p>

Study on the correlation between positive rates of SARS RNA in clinical confirmed SARS patients and the appearance of RNA in relation to the development of the disease / 中华流行病学杂志

<p><b>OBJECTIVES</b>To study the correlation between positive rates of RNA in clinical confirmed severe acute respiratory syndrome (SARS) patients and its appearance in relation to the development of the disease in order to provide scientific basis for early diagnosis, effective prevention and treatment of the disease.</p><p><b>METHODS</b>One-step reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify the SARS RNA in the clinical specimens from different courses of the disease. The representative amplicons were then sequenced. Chi-square for trend test was performed to study the correlation between positive rates of RT-PCR and at different periods after the onset of the disease.</p><p><b>RESULTS</b>The fragments amplified from the sputum specimens of SARS patients were shown to share 100% homology with the published SARS-associated coronavirus. Of the different clinical specimens, positive rate in the stools appeared to be the highest (21.55%). Chi-square for trend test revealed that the positive rates of stools and sputa of SARS patients decreased with the development of the disease (chi(2) for trend = 12.55 and 16.408, P = 0.0004 and P = 0.000 05 respectively).</p><p><b>CONCLUSION</b>One-step RT-PCR proved to be an effective method for the detection of SARS-associated coronavirus from clinical specimens. Data as indicated that the positive rates of SARS coronavirus were decreasing in SARS patients along with the disease progression.</p>

Using geographic information system to study on the association between epidemic areas and main animal hosts of hemorrhagic fever with renal syndrome in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the association between types of epidemic areas and proportion of main animal hosts of hemorrhagic fever with renal syndrome (HFRS) in China.</p><p><b>METHODS</b>Data on serotype of HFRS patients from 122 regions and species as well as number of animal hosts from 41 national surveillance sites were collected and managed. The map of the types of epidemic areas from 1991-1999 in China was produced using inverse distance weighted technique in the ArcGIS 8.1 software. The map of the proportion of host animals was then overlapped on it and the surveillance sites of HFRS were clustered in terms of the proportion of host animals.</p><p><b>RESULTS</b>Variance in spatial distribution of the types of epidemic areas was observed. Two epidemic area types, namely Hantaan-dominant mixed epidemic areas and Soul-dominant mixed epidemic areas seemed to have transferred from the north-east to south-west of China in turns. There were more species of HFRS animal hosts in fields than those of in residential areas. The diversity of rodent species in fields was higher than that of the residential areas which predominant harbored rodent species of 2-3 kinds. Types of surveillance sites classified by cluster analysis of proportion of main animal hosts were consistent with the serotypes of HFRS patients.</p><p><b>CONCLUSION</b>Through employment of spatial analysis technique based on GIS databases, the HFRS types of main epidemic area in China could be well predicted by surveillance data.</p>

Study on the application of geographic information system in spatial distribution of hemorrhage fever with renal syndrome in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the spatial distribution of hemorrhagic fever with renal syndrome (HFRS) in China by geographic information system, and to draw up a map on HRFS risk areas.</p><p><b>METHODS</b>A set of database was set up using the information collected and linked to electronic maps of China in a software ArcGIS 8.01 from 41 HFRS surveillance sites during 1995 - 1998. A HFRS spatial distribution model was developed using inverse distance weighted interpolation of ArcGIS's spatial analysis method. The normalized difference vegetation index (NDVI) in each HFRS surveillance site was extracted from SPOT4 satellite vegetation imagery. Correlation analysis was performed through SPSS 10.0 to analyze the association between NDVI and HFRS incidence, HFRS risk areas were mapped under different colors.</p><p><b>RESULTS</b>Spatial distribution model from HFRS surveillance sites showed that HFRS foci mainly presented in the Heilongjiang River drainage, the middle and lower reaches of the Yellow River, the middle and lower reaches of the Yangtze River, and the Jinghang grant Canal-Huaihe River drainage. It was consistent with HFRS distribution map derived from national infectious disease reporting system. Correlation analysis indicated that HFRS incidence rates were significantly associated with NDVI (r = 0.417, P < 0.01). The HFRS risk areas was mapped according to NDVI of each surveillance site.</p><p><b>CONCLUSION</b>It is promising to apply GIS technology in predication of the distribution of HFRS by establishing this prediction model.</p>

The application of indirect immuno-fluorescence assay in the diagnosis of severe acute respiratory syndrome / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the temporal profile of serum antibody against coronavirus in patients with severe acute respiratory syndrome (SARS), and to evaluate the reliability of indirect immuno-fluorescence assay (IFA) in the diagnosis of SARS.</p><p><b>METHODS</b>Clinically confirmed SARS patients, suspected SARS patients, and controls were included in the study. IFA was used to detect the serum antibody against SARS coronavirus. General information about the subjects was collected using a standard questionnaire.</p><p><b>RESULTS</b>The positive rates of specific IgG and IgM against SARS virus within 10 days after onset of the disease were 55.1% and 16.3% respectively and then increased up to 89.8% for IgG and 65.3% for IgM. After 25 days of the onset of the disease, 90.9% patients became positive for both IgG and IgM. Results from chi-square for trend test revealed that the positive rates of both IgG and IgM increased with time (chi(2) for trend = 16.376, P = 0.00005 for IgG; chi(2) for trend = 28.736, P = 0.00000 for IgM). Sensitivity, specificity and agreement value of IFA regarding the diagnosis of SARS were all higher than 90%.</p><p><b>CONCLUSION</b>IFA can be used to assist diagnosis of SARS after 10 days of the onset of disease.</p>

Spatial analysis on the distribution of hemorrhagic fever with renal syndrome by geographic information system in Haidian district, Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the spatial distribution of hemorrhagic fever with renal syndrome (HFRS) in Haidian district, Beijing and to explore the geographical characteristics of HFRS in highly endemic areas.</p><p><b>METHODS</b>Administration boundary layer was established under the background of 1:100,000 map in the ArcInfo 8.1 software. The HFRS cases from 1997 to 2002 were positioned on the map. Highly endemic areas were identified by spatial cluster analysis using SaTScan 3.0 software. Distribution of HFRS cases was shown in different colors and contours by spatial analysis of geographic information system (GIS).</p><p><b>RESULTS</b>Spatial Cluster Analysis of confirmed cases of HFRS identified in 1997 - 2002 in Haidian district showed that HFRS patients were not randomly distributed. The highly endemic areas were founded in Sujiatuo township, Yongfeng township, Shangzhuang township, Wenquan town and Bei'anhe township (relative risk = 4.43, P = 0.001). A thematic map of HFRS in haidian district was set up.</p><p><b>CONCLUSION</b>HFRS infections were not randomly distributed, since the distribution was related to geographic-environmental factors.</p>