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.

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.

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.

Laboratory confirmation of the first influenza A (H1N1) imported case in Mainland China / 病毒学报

The clinical throat swab specimen of an imported suspected case of influenza A (H1N1) was detec ted with real-time PCR, RT-PCR and subsequently confirmed by gene sequencing. The presence of influ enza A (H1N1) virus confirmed the first case with A (H1N1) infection in Mainland China.

Amplification and restriction fragment length polymorphism analysis on the complete sequence of Sta56 gene of Orientia tsutsugamushi isolated from Shandong area / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the genetic differences of Orientia tsutsugamushi (Ot) Sta56 gene between Shandong isolates and other strains deposited in GenBank.</p><p><b>METHODS</b>PCR and restriction fragment length polymorphism (RFLP) were used to amplify the complete sequence of Ot-Sta56 gene. RFLP profiles of Ot were predicted by a computer program according to their complete sequences of Ot-Sta56 gene. PCR amplicon from XDM2 strain was sequenced and analyzed by Clustal X (1.8) and PHYLIP software.</p><p><b>RESULTS</b>The complete sequences (about 1.6 kbp) of Ot-Sta56 gene were amplified from B16 strain (isolated from patients), FXS2 strain (isolated from A. agrarius) and XDM2 strain. Four species of restriction endonucleases (Hha I, Hinf I, Hae III, Pst I) were used to digest the PCR amplicons from the 3 isolates. When comparing with the RFLP profiles of prototype Ot, the RFLP profiles of PCR amplicons from the 3 isolates were similar to those of Japan Kawasaki strain, but were quite different from the international reference strains Gilliam, Karp, Kato. Results from DNA sequence analysis showed that the complete sequence of Ot-Sta56 gene homology to Japan Kawasaki strain of XDM2 strain was 97%, and deduced amino acid sequence was 92%.</p><p><b>CONCLUSION</b>Data from the complete sequence of Sta56 gene indicated that the genotypes of Ot isolates in Shandong province were similar, but with distinction from the Kawasaki strain.</p>

Transmission models of tuberculosis in heterogeneous population / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To review the transmission models of tuberculosis in heterogeneous population.</p><p><b>DATA SOURCES</b>The data used in this review were adopted mainly from the studies of models of tuberculosis reported from 1995 to 2006.</p><p><b>STUDY SELECTION</b>Relevant literature on transmission models of tuberculosis in heterogeneous populations are referenced.</p><p><b>RESULTS</b>Casual/random factors and genetic factors are the main reasons for epidemics of tuberculosis in recent years. Mass public transport is playing the primary role in casually close contact which can facilitate the transmission of tuberculosis. Genetic susceptibility not only varies endemic prevalence levels, but also drastically alters the effects of treatment for tuberculosis patients. Detailed studies further exhibit that casual contact and genetic factor are responsible for over 30% - 40% of the total new cases in recent years. The prevalence of tuberculosis could double (from 33% to 60%) if a genetically susceptible phenotype is present in only 30% of the population. And some challenges have emerged along with these exciting results.</p><p><b>CONCLUSIONS</b>Casual/random contact, public transport and genetic susceptibility are responsible for most new tuberculosis cases and a wide variation in endemic tuberculosis levels between regions. Hence, the transmission model of tuberculosis in a heterogeneous population can provide more clues to underlying mechanism of tuberculosis transmission than in a homogeneous population. However, many challenges remain for us in understanding transmission of disease.</p>

Identification of Amur like virus in Apodemus peninsulae and its molecular characteristics in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To confirm the existence of Amur-like viruses in Apodemus peninsulae in China, and to understand the molecular characteristics of these viruses.</p><p><b>METHODS</b>Total RNA was extracted from lungs of A. peninsulae captured in Jilin of Northeast China with Trizol reagent. Complete S and partial M segments of Amur virus were amplified and sequenced. Phylogenetic analyses on multiple nucleotide sequences were performed with the Clustal method and DNASTAR software.</p><p><b>RESULTS</b>383 bp cDNA of M segment and 1696 bp of S segment of Amur like virus were recovered from lung tissue of A. peninsulae, named JilinAP06. The full-length of its S gene comprised of 1696 nucleotides with ORF including 1287 nucleotides and encoding a protein which comprised 429 amino acids. The phylogenetic analysis of this sample with other hantaviruses revealed that the complete S and partial M segment sequence of JilinAP06 both were closely related to those Amur viruses such as AP63, AP61, AP1371 and AP1168 found in A. peninsulae from Far East region of Russia and B78 strain, Liu strain and H5 strain, which were all from Chinese patients. The complete S and partial M segment sequence of JilinAP06 had only 81.0% identities with the nucleotide sequences of HV prototype 76-118 strain.</p><p><b>CONCLUSION</b>Amur-like viruses did exist in A. peninsulae from Northeasern China while A. peninsulae might be the natural reservoir of Amur-like viruses in China and was the important infectious source to HFRS patients which were caused by Amur-like viruses.</p>

Investigation on Anaplasma phagocytophilum infection in rodents from forest areas in northeastern China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence of Anaplasma phagocytophilum in rodents from forest areas in northeastern China.</p><p><b>METHODS</b>PCR amplification, followed by sequence analysis was carried out. The sequences of 16S rRNA and gltA gene fragment amplified from rodent specimens were compared with corresponding part of the sequences deposited in GenBank.</p><p><b>RESULTS</b>A total number of 276 rodents were tested, including 102 in Jilin province, 61 in Helongjiang province and 113 in Inner Mongolia autonomous region. The positive rates were 8.82%, 1.64% and 0.00%, respectively. The infection rate in rodents infected by ticks was 11.30 times higher than that in rodents without ticks (P = 0.002). The S. A. phagocytophilum 16S rRNA sequences from rodents in Jilin and Heilongjiang were identical and differed in 3-5 bases compared with the corresponding parts of A. phagocytophilum from America, Sweden and Japan. Compared with the sequences registered in GenBank, the nucleotide sequence of gltA varied from 87%-97% and its deduced amino acid sequence changed from 84%-99%.</p><p><b>CONCLUSION</b>A. phagocytophilum infection was presented in rodents from Jilin and Heilongjiang province.</p>

A three-year follow-up study on sera specific antibody in severe acute respiratory syndrome cases after the onset of illness / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the variation of specific antibody among convalescent of severe acute respiratory syndrome (SARS) patients through a three-year program.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Investigation on hantaviruses infection in rodents from free markets in Beijing areas / 中华流行病学杂志

<p><b>OBJECTIVE</b>In order to find out the factors related to hemorrhagic fever with renal syndrome (HFRS) infection, and to evaluate the probability of ecdemic hantaviruses (HV) infection in rodents in Beijing areas.</p><p><b>METHODS</b>Rodents were collected in a large-scale railway station and a produce market with 'trap nights' method from April to May, 2004. The IgG reacting sera to HV antigen were detected using ELISA. The partial M and S segment of HV from captured rodent lung samples were amplified with RT-PCR. The PCR products were purified and sequenced. BLAST program was then used to perform on nucleotide pairwise alignment with all available sequence in GenBank. The alignment of the multiply nucleotide and the deduced amino acid sequences, together with phylogenetic analysis were completed with DNASTAR software.</p><p><b>RESULTS</b>The average population density was 3.49% (24/690). The overall seroprevalence of HV infection was 8.3% (2/24). RT-PCR positive rates were 8.3% (2/24). The nucleotide sequences of 356 bp region (1958 - 2313) of M segment obtained from 2 samples were all identified to Seoul virus (SEOV), with 7.6% heterogeneity. The dc501 strain from railway station was closely related to SD227 and Hebei4 from Shandong and Hebei provinces respectively. BjFT01 strain from the farm product market had more special nucleotide transitional mutations than other known SEOV from Beijing in GenBank. This strain, together with known HN71 from Hainan province, K24-E7 from Zhejiang province, L99 from Jiangxi province and R22 from Henan province, represented a monophylogentic linkage.</p><p><b>CONCLUSION</b>The higher HV prevalence of rodents in transportation center was the potential and important risk for HFRS epidemic in Beijing. The increasing prevalence of M. musculus should call for attention. It was possible that SEOV in Beijing was imported by infected rodents through vehicles from other provinces.</p>

Study on the association between hantavirus infection and Rattus norvegicus / 中华流行病学杂志

<p><b>OBJECTIVE</b>To further understand the association of hantavirus (HV) harbored and transmitted in wild brown rats.</p><p><b>METHODS</b>Rattus norvegicus (n = 570) were trapped in 10 sites in Beijing. RT-PCR was used to test rodent lung samples for hantavirus infection. Unconditional multivariate logistic regression analysis was performed, with PCR positive as the dependent variable and the characteristics of Rattus norvegicus population as independent variables.</p><p><b>RESULTS</b>The overall HV prevalence in Rattus norvegicus was 9.1% (52/570). Significant association between HV infection in Rattus norvegicus and some biological characteristics of host population was observed. Adult Rattus norvegicus had a higher HV prevalence than juveniles. Males in the reproduction periods and rats with wounds were more likely to be infected with HV than others.</p><p><b>CONCLUSION</b>It was further confirmed that there existed parallel transmission of HV in Rattus norvegicus hosts. Aggression might be the primary mode of HV transmission among male Rattus norvegicus.</p>

Study on the coinfection status of Borrelia burgdorferi sensu lato and spotted fever group Rickettsia in ticks from Hunchun, Jilin province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the coinfection status of Borrelia burgdorferi sensu lato (B.b.s.l) and spotted fever group Rickettsia (SFGR) in Hunchun of Jilin province, China.</p><p><b>METHODS</b>Polymerase chain reaction (PCR) was used to detect the 5S-23S rRNA intergenic spacer of B. b. s. l and ompA of SFGR in ticks was collected in Hunchun,Jilin province. The amplification products of positive ticks were sequenced, and phylogenetic analysis was conducted by PHYLIP software package.</p><p><b>RESULTS</b>The infection rate of B. b. s. l was 36.0% in Ixodes persulcatus ticks and the SFGR was discovered in I. persulcatus ticks,with an infection rate of 2.0%. The coinfection rate of both agents was 2.0%. In 327 Dermacentor siltarum ticks, the positive rates of B. b. s. l and SFGR were 30.9% and 29.1% respectively. 55 ticks (16.8%) were coinfected with the two pathogens. The sequence analysis of B. b. s. l showed that the B. b. s. l in Jilin area, which were highly homologous, all belonged to B. garinii genotypes. The sequence analysis of SFGR positive products showed that the DNA secquence of the newly detected agent (JL-95) was close to the two previously described rickettsiae which were detected in I. ricinus from Slovakia (called IRS3 and IRS4). Phylogenetic relationships inferred from the comparison of these sequences with those of other genus Rickettsiae indicated that JL-95, IRS3 and IRS4 constituted a new rickettsial genotype and formed a separate cluster among the spotted fever group Rickettsiae.</p><p><b>CONCLUSION</b>Coinfection of B. b. s. l and SFGR existed in Hunchun, Jilin province. The sequencing of specific fragment confirmed a new SFGR which was different from other rickettsiae known in China.</p>

Investigation on rodents' natural infection of Orientia tsutsugamushi in some areas of Inner Mongolia and Xinjiang, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate rodents' natural infection of Orientia tsutsugamushi (Ot) in some areas of Inner Mongolia and Xinjiang, China.</p><p><b>METHODS</b>DNAs were extracted from spleens of the captured mice and nested-polymerase chain reaction (nPCR) technique was used to detect the Ot-Sta56 gene. Six positive samples were sequenced and analyzed by Clustal X (5.0) and DNA Club software.</p><p><b>RESULTS</b>A total of 90 rodents were captured in Inner Mongolia, and the overall prevalence of Ot was 6.67%. There was no significant difference in infection rates among the positive rodents species. 20 rodents were captured in Xinjiang, and the prevalence of Ot was 5.00%. The geographical difference in infection rates was not statistically significant between Inner Mongolia and Xinjiang. 9 rodents were captured in farmlands of Inner Mongolia and Xinjiang but there was no positive samples found. 101 rodents were captured in grasslands, and the prevalence of Ot was 6.93%. The Sta56 gene nucleotide sequence homology to Karp strain of N59 (from Microtus maximowiczii), N69 (from Cricetulus barabensis) and X33(from Cricetus cricetus) was 99%. The sequence homology to Taitung-2 strain and TW461 strain of N65 (from C. barabensis) was 94%, and the sequence homology to Taitung-2 strain and TW461 strain of N88(from Apodemus agrarius) was also 94%. The sequence homology to Oishi strain of N90 (from A. agrarius) was 96.00%.</p><p><b>CONCLUSION</b>Our findings indicated that infections of Ot did exist in rodents captured from Inner Mongolia and Xinjiang. The genotypes of Ot in Inner Mongolia and Xinjiang were quite complex, with some of them belonged to Karp type, and the others belonged to Taitung-2, TW461 and Oishi types which providing evidence for further investigation on the scrub typhus fuci in the two areas.</p>

Investigation on Borrelia burgdorferi sensu lato in ticks and rodents collected in Da Xing-An Mountains Forest areas of China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To detect and study the types of Borrelia burgdorferi sensu lato in ticks and rodents from Da Xing-An Mountains Forest areas of China.</p><p><b>METHODS</b>Nested PCR was performed to amplify 5S-23S rRNA intergenic spacer of B. burgdorferi. Positive products were analysed by restriction fragment length polymorphism (RFLP) and single strand conformation polymorphism (SSCP), specimens showing unique RFLP profile were sequenced and analysed.</p><p><b>RESULTS</b>1336 Ixodes persulcatus, 144 Dermacento silvarum, 144 Haemaphysalis concinna and 145 rodents of 9 species were collected from 16 sections of Da Xing-An Mountains Forest areas of China. Specific fragments were amplified from 293 I. persulcatus and 6 D. silvarum and 5 rodents of 4 species. B. burgdorferi was not detected in H. concinna. Among the positively tested I. persulcatus, 209 contained B. garinii genospecies and 45 contained B.afzelii genospecies based on RFLP. Moreover, B.garinii genospecies consisted of B. garinii 20047 and B. garinii NT29. 17 adult I. persulcatus were simultaneously infected with B. garinii 20047 and B. garinii NT29. Nine adult I. persulcatus were simultaneously infected with B. garinii 20047 and B. afzelii. Four adult I. persulcatus were simultaneously infected with B. garinii 20047 and B. garinii NT29 and B. afzelii. Two D. silvarum were infected with B. garinii 20047, 1 D. silvarum with B. garinii 20047, 2 D. silvarum with B. afzelii. 3 rodents were infected with B. garinii 20047 while 2 rodents were infected with B. garinii NT29. Mixed infection was not found in D. silvarum and rodents. In addition, nine I. persulcatus and one D. silvarum specimens showed unique RFLP pattern. Data from sequential analysis showed that they all belonged to B. garinii. PCR-SSCP profiles of 5S-23S rRNA intergenic spacer of B. burgdorferi in the positive specimens exceeded 36 types; B. garinii 20047 showed 16 types while B. garinii NT29 showing 11 types, B. afzelii showing 9 types. SSCP profiles of the specimens coinfected with multiple B. burgdorferi was relatively complex.</p><p><b>CONCLUSION</b>The infection of B. burgdorferi was found in the ticks and rodents in Da Xing-An Mountains Forests areas. The infection rate of I. persulcatus was high. B. garinii was predominant genospecies, and the population of B. burgdorferi was heterogeneous in the area. Mixed infections of different B. burgdorferi genospecies in ticks were found. I. persulcatus and Clethrionomys rufocanus were possibly served as major vector and major host for B. burgdorferi, respectively, suggesting that further study is needed to confirm the coinfection in humans and animals in this region.</p>

Comparison and discrimination of the biological characteristics between West Nile virus and Japanese encephalitis virus / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To compare the biological characteristics of West Nile virus (WNV) and Japanese encephalitis virus (JEV), including cells sensitivity, pathogenicity, viral morphology, as well as the results of immunological and molecular biological detection.</p><p><b>METHODS</b>Cytopathic effect (CPE) and pathogenicity were observed in C6/36 cells and in suckling mice inoculated intracerebrally with the WNV or JEV, respectively. The sliced tissue samples for electron microscopic examination were prepared for the morphologic observation of the viruses. Serum antibody to WNV or JEV was detected using indirect immunofluorescence assay (IFA), and the viral RNA was analyzed by RT-PCR method.</p><p><b>RESULTS</b>WNV or JEV-caused CPE was characterized by cell fusion and cell shedding, respectively. There was no significant difference in the pathogenicity to suckling mice between WNV and JEV. The morphologic observation showed that the shape and size of the two virions were similar. WNV and JEV were found to have antigenic cross-reactivity. The viral RNA could be detected from both WNV and JEV samples with universal primer set, but only nucleoside fragments of corresponding virus could be amplified when specific primers were used.</p><p><b>CONCLUSION</b>CPE in C6/36 cell and detection of the viral RNA should be useful in discrimination of WNV and JEV, and simultaneously examining the titers of serum antibodies against WNV and JEV may be helpful to diagnosis of infection with these agents.</p>