Epidemiological characteristics of imported COVID-19 cases in Beijing / 中华流行病学杂志

Objective: To analyze the epidemiological characteristics of imported COVID-19 cases and the effect of vaccination on virus load and disease severity of the cases in Beijing. Methods: The data of the imported COVID-19 cases in Beijing were collected from the National Notifiable Infectious Disease Reporting System of China Information for Disease Control and Prevention and Epidemiology investigation. The data were processed and analyzed by Excel 2010 and SPSS 22.0. Results: From June 1 to September 30, 2021, a total of 171 imported COVID-19 cases were reported in Beijing, of which 66.67% (114/171) were asymptomatic. The cases were mainly from the Philippines, the United Arab Emirates, the United Kingdom and the Russian Federation, accounting for 67.84% (116/171). The male to female ratio of the cases was 2∶1 (114∶57). The median age M (Q1, Q3) of the cases was 28 (23, 36) years. The cases of Chinese accounted for 80.12% (137/171). The sequencing of the whole genome of the virus in 47 imported COVID-19 cases showed that the proportion of Delta variant was 76.60% (36/47). The COVID-19 vaccination coverage rate in the cases was 60.82% (104/171), but the full vaccination coverage rate was 53.80% (92/171). In the imported COVID-19 cases, 13.53% (23/170) were screened to be SARS-CoV-2 nucleic acid positive on the day when they arrived in Beijing, and all the cases were positive for 2019-nCoV nucleic acid within 28 days. The severity of the disease was higher in the unvaccinated group than in the partially vaccinated group and fully vaccinated group (P<0.001). In the unvaccinated group, there were 1 severe case and 1 critical case. The median Ct values M (Q1, Q3) of N gene and ORFlab gene in unvaccinated group were 32.51 (23.23, 36.06) and 32.78 (24.00, 36.38), respectively. There was no significant difference in the median of double-gene Ct value between the partially vaccinated group and the fully vaccinated group. Conclusions: During the study period, most of the imported COVID-19 cases in Beijing were asymptomatic. No matter vaccinated or not, the viral loads in the COVID-19 cases were similar, but the vaccination could reduce the severity of the disease.

Epidemiological characteristics of hand, foot and mouth disease among people aged 6 and over in Beijing, 2011-2020 / 中华流行病学杂志

Objective: To analyze the epidemiological characteristics of hand, foot and mouth disease (HFMD) among people ≥6 years old in Beijing from 2011 to 2020. Methods: The incidence data of HFMD cases from 2011 to 2020 were collected from the National Notifiable Infectious Disease Reporting System of China Information for Disease Control and Prevention and the etiological surveillance of HFMD in 29 sentinel hospitals from 16 districts of Beijing. Descriptive epidemiological methods were used to analyze the distributions, pathogen constituents, and changes of HFMD cases in Beijing people ≥6 years old. Results: From 2011 to 2020, a total of 38 183 cases of HFMD were reported among people ≥6 years old in Beijing, of which 46 (0.12%) cases were severe. The average annual reported incidence was 19.04/100 000. The ratio of males to females were 1.37∶1(22 064∶16 119). The proportion of HFMD in people ≥6 years old increased from 7.56%(2 606/34 488) in 2011 to 24.54% (546/2 225) in 2020. The average incidence of HFMD was higher in Shunyi district, Yanqing district, and Tongzhou district than in other districts in Beijing. The positive rate of enterovirus in sentinel surveillance was 66.78% (1 976/2 959), the proportion of enterovirus group A 71 (EV-A71) was 45.29% (101/223) in 2014, no EV-A71 positive was detected in 2020, and the proportion of Coxsackievirus A 6 (CV-A6) increased from 15.11% (34/225) in 2016 to 81.08% (60/74) in 2020. Conclusions: From 2011 to 2020, the proportion of cases with HFMD in people ≥6 years old in Beijing increased yearly, and the proportion of EV-A71 positive patients decreased basically. Since 2016, CV-A6 has gradually become the dominant pathogen. More attention should be paid to the epidemic situation and dynamic pathogen changes of hand foot mouth disease in people ≥6 years old.

Application of two RT-PCR methods for detection of norovirus in market-sold oysters and norovirus genetic characteristic analysis, a survey conducted in Beijing / 中华流行病学杂志

Objective: To evaluate the application of real-time RT-PCR and semi-nested RT-PCR in the detection of norovirus in oysters and analyzing the genetic characteristics of the isolates. Methods: Real-time fluorescent RT-PCR and semi-nested RT-PCR were used to detect norovirus GⅠ/GⅡ in fresh oysters collected from the markets in Beijing from November 2014 to October 2015. The detection rate of the parallel test was also analyzed. In addition, the reliability of semi-nested RT-PCR was evaluated by agreement rate and consistency test (Kappa value). The positive products of norovirus GⅠ/GⅡ capsid protein region gene by semi-nested RT-PCR were sequenced. Software BioEdit 7.0.9.0 was used for sequence alignment, and software Mega 6.0 was used to construct the evolutionary tree. Results: In 72 samples, the detection rate of norovirus was 31.94% (23/72) by real-time RT-PCR, 38.89% (28/72) by semi-nested RT-PCR and 48.61% (35/72) by parallel test. The coincidence rate of the two methods was 73.61%, a moderate degree (Kappa value =0.43). A total of 13 norovirus strains were successfully sequenced, and 11 strains (7 GⅡ.17 strains, 2 GⅡ. 4 Sydney_ 2012 strains, 1 GⅡ. 1 strain and 1 GⅡ. 21 strain) were obtained from norovirus positive samples by two RT-PCR methods, two strains (1 GⅡ. 17 strain and 1 GⅡ. 3 strain) were obtained from real-time RT-PCR negative samples which were positive for norovirus by semi-nested RT-PCR. The similarity between these strains and reference strains from diarrhea patients, environmental sewage, and shellfish products were 84.4% - 100.0%. Conclusions: The parallel test of norovirus in oysters by two RT-PCR methods can improve the detection rate and detect more genotypes. Norovirus strains in oysters were highly homologous with reference strains from diarrheal patients, environmental sewage, and shellfish products. Therefore, surveillance, prevention and control for norovirus should be carried out in people who have frequent contacts with oysters and related environments.

Lyme Borreliosis-associated Risk Factors in Residents of Beijing Suburbs: a Preliminary Case-control Study / 生物医学与环境科学（英文）

A population-based case-control study was conducted to evaluate the relative factors in the environments, agricultural works, outdoor activities, and the effectiveness of Lyme borreliosis (LB)- associated personal protective measures in Beijing. Thirty-four cases and 272 controls were personally interviewed by well-trained interviewers. Venous blood samples were taken from each subject. Sowing or harvesting in summer (OR=2.571, 95% CI: 1.109-5.962), living in house with weeding in the yard (OR=2.247, 95% CI: 1.062-4.755), and residence at the plain area (OR=2.630, 95% CI: 1.050-6.588) were the independent relative factors for seropositive LB. Wearing long pants and clothes with cuffs was the only protective behavior against tick bite (OR=0.186, 95% CI: 0.041-0.846). The findings showed that local farmers were easily infected with LB and almost no protective measure was taken against LB infection. Infection with LB was easier in residents of plain regions. Pets raising and outdoor activities were not the risk factors for infection with LB. Further studies are needed to fully understand the risk of infection with LB in China.

The genetic features of drug resistance to group A streptococcus and macrolides antibiotics among pediatric patients in Beijing 2012 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the genetic features of drug resistance to group A streptococcus(GAS) and macrolides antibiotics among pediatric patients in Beijing 2012.</p><p><b>METHODS</b>A total of 199 strains of GAS were collected from 36 hospitals in Beijing between May and July, 2012. All strains were isolated from oropharyngeal swabs. The minimum inhibitory concentrations (MICs) of ten antibiotics (penicillin, ampicillin, erythromycin, clindamycin, tetracycline, levofloxacin, tigecycline, vancomycin, linezolid and streptogramin) were detected by VITEK-2 compact with GPS-67 test kit. The genes encoding macrolides resistance (ermA, ermB and mefA ) were amplified and tested by PCR. The macrolides resistant phenotype of group A streptococcus was detected by double disc test (D-test).</p><p><b>RESULTS</b>Among 199 strains of GAS collected in this study, 101(50.8%) were from suburbs and the other 98(49.2%) were from urban areas. 111(55.8%) strains were collected from scarlet fever patients while the other 88(44.2%) were from oropharyngeal infection cases. All the strains were sensitive to penicillin and ampicillin, and the percentage of resistance to erythromycin, clindamycin and tetracycline were 96.5% (192/199), 95.5% (190/199) and 92.0% (183/199), respectively. All strains were susceptible to levofloxacin, tigecycline, vancomycin, linezolid and streptogramin. The rates of resistance to erythromycin, clindamycin and tetracycline were different in different districts, however, the difference in it between ages and clinical diagnosis did not show statistical significance (P > 0.05) . The detected rate of drug resistance gene ermB was 98.5% (196/199). The gene ermA was only detected out in 5 strains and the gene mefA was not detected out. 199 strains showed A macrolides resistant phenotype cMLS, while the phenotype iMLS was not found in this study.</p><p><b>CONCLUSION</b>This study demonstrates the high level of clindamycin resistance in group A streptococcus collected from children in Beijing, 2012. The macrolides resistance of group A streptococcus was highly prevalent in Beijing, and the dominant phenotype was cMLS mediated by gene ermB.</p>

Analysis on the whole genome of the influenza H1N1 virus of the mild and severe cases in Beijing in 2009 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the characteristics of the whole genome of the influenza H1N1 virus of the mild and severe cases in Beijing.</p><p><b>METHODS</b>A total of 21 samples of throat swabs were collected from surveillance-designated hospitals between June and December in 2009, including 10 severe cases (4 death cases) and 11 mild cases. RNA of the virus were extracted,and the amplified primers of the whole genome were designed.Reverse transcription and PCR were performed to the RNA and then the PCR product was sequenced by software to analyze the evolution of the viral genes and the variation of the amino acids.</p><p><b>RESULTS</b>Compared with the reference vaccine strain A/California/07/2009 (H1N1), the genetic nucleotide homology in the eight segments of the pandemic H1N1 virus in Beijing in 2009 was higher than 99%, without significant variation. Among them,the genetic distance of hemagglutinin (HA), neuraminidase (NA) and nucleoprotein (NP) was comparatively far, separately 0.0050, 0.0040 and 0.0040.The gene of HA, P83S, the gene of NA, N248D, the gene of polymerase (PA), P224S and the gene of NP, V100I and L122Q were found to mutate in all the samples. Genes of HA, NA, NP, PA, PB 2 and nonstructural protein (NS1) in severe cases showed obviously clustered evolution. The mutation of gene S128P and S203T of HA, gene R269R and D547E of PA, gene T588I of PB 2 and gene I123V of NS mainly happened in severe cases, separately counting 6, 9, 6, 7, 9 and 6 cases. The relevance between the mutation happened in S203T of HA, R269K and D547E of PA and the severeness of the cases showed statistical significance (P < 0.05). The mutations of HA gene were mainly on the Ca and Cb antigene domains. No drug resistant mutation was found on NA gene but happened on matrix protein 2 (M2 gene). None of the mutations were found on the virulence related genes.</p><p><b>CONCLUSION</b>A high homology was found between the pandemic H1N1 virus in Beijing in 2009 and the reference vaccine strain A/California/07/2009(H1N1). Mutational sites related with the severe and fatal cases were found, but not the virulence related mutation.</p>

Early detection on the onset of scarlet fever epidemics in Beijing, using the Cumulative Sum / 中华流行病学杂志

[Introduction] Based on data related to scarlet fever which was collected from the Disease Surveillance Information Reporting System in Beijing from 2005 to 2011,to explore the efficiency of Cumulative Sum (CUSUM) in detecting the onset of scarlet fever epidcmics.Models as C1-MILD (C1),C2-MEDIUM (C2) and C3-ULTRA (C3) were used.Tools for evaluation as Youden' s index and detection time were calculated to optimize the parameters and optimal model.Data on 2011 scarlet fever surveillance was used to verify the efficacy of these models.C1 (k=0.5,H=2σ),C2 (k=0.7,H=2σ),C3 (k=1.1,H=2σ) appeared to be the optimal parameters among these models.Youden' s index of C1 was 83.0％ and detection time being 0.64 weeks,Youden' s index of C2 was 85.4％ and detection time being 1.27 weeks,Youden' s index of C1 was 85.1％ and detection time being 1.36 weeks.Among the three early warning detection models,C1 had the highest efficacy.Three models all triggered the signals within 4 weeks after the onset of scarlet fever epidemics.The early warning detection model of CUSUM could be used to detect the onset of scarlet fever epidemics,with good efficacy.

Prevalence of hepatitis B in Chaoyang district, Beijing in 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the prevalence of hepatitis B infections and carrier status among general population in Chaoyang district, Beijing in 2010.</p><p><b>METHODS</b>From May to December 2010, 14 491 subjects over 12 months old were selected by multistage random cluster sampling method from residents in Chaoyang district, Beijing. Five millilitre venous blood specimens were collected from these subjects to test hepatitis B virus antigens and antibodies. Status of hepatitis B infections were analyzed in different age, sex and registered permanent residence groups.</p><p><b>RESULTS</b>The overall positive rate of surface antigen (HBsAg) was 2.66% (383/14 410). The lowest rate of 0.56% (9/1603) was found in the 1 to 14 years old group and the 35 to 44 years old group had the highest rate of 4.27% (92/2154). The rate in subjects younger than 24 years old was 1.03% (31/2986). The overall positive rate of surface antibody (anti-HBs) was 40.21% (5798/14 421). The highest positive rate of anti-HBs (80.59%, 407/505) was found in the 1 to 4 years old group. The overall positive rate of core antibody (anti-HBc) was 30.26% (4364/14 424). The overall hepatitis B virus infection rate was 30.32% (4364/14 393). For male and female groups, the positive rates of HBsAg were 2.93% (179/6108) and 2.44% (202/8287) respectively (χ² = 3.32, P > 0.05); anti-HBs were 41.93% (2563/6113) and 38.96% (3231/8293) respectively (χ² = 12.88, P < 0.01); and anti-HBc were 31.39% (1919/6114) and 29.39% (2438/8295) respectively (χ² = 6.65, P = 0.01). For local residents group and mobile population group, the positive rates of HBsAg were 2.46% (283/11 510) and 3.60% (98/2719) respectively (χ² = 11.08, P < 0.01); anti-HBs were 37.11% (4293/11 568) and 53.07% (1445/2723) respectively (χ² = 233.51, P < 0.01); and anti-HBc were 30.83% (3567/11 570), and 28.41% (774/2724) respectively (χ² = 6.08, P < 0.05).</p><p><b>CONCLUSION</b>The positive rate of HBsAg in population younger than 24 years old has reached a relatively low level. The mobile population has significantly higher positive rate of HBsAg than local residents, indicating the need for enhancing prevention and control measures for hepatitis B for the mobile population and local residents over 25 years old.</p>

Study on the risk factors of diarrhea-related behaviors among adults in Beijing / 中华流行病学杂志

Objective To study the risk behaviors on diarrhea among the adults of Beijing.Methods 13287 adults aged over 18 years in Dongcheng,Xicheng,Haidian,Changping,Huairou and Tongzhou districts in Beijing were selected with a multi-stage stratified sampling method.Information on the demographic characteristics,with or without symptoms on diarrhea in the last year,and behaviors related to diarrhea,were collected through a self-designed questionnaire.Results The reported total prevalence of diarrhea symptoms in the last year was 17.6％ and,in urban areas as 16.8％,in rural areas as 18.2％ respectively.The differences on the reported prevalence rates of diarrhea in different age groups,background of education and occupations groups among urban residents were statistically significant (P＜0.05).Items as eating raw seafood or freshwater products,using the same chopping block and knife at the time when processing raw and cooked food,not being used to regular physical exercise etc.were the risk factors to diarrhea among adults from urban areas,with OR (95％CI) as 1.26 ( 1.07-1.48),1.37 (1.16-1.63) and 1.38 ( 1.20-1.59),respectively.The reported diarrhea prevalence rates related to sex,age,education background and occupations among rural residents did not show significant differences (P＞0.05).Without hand-washing habit before eating or after toilet-using,eating raw seafood or freshwater products,using the same chopping block and knife at the time when processing raw and cooked food,not being used to regular physical exercise etc.seemed to be the risk factors on diarrhea among adults in the rural areas with the OR(95％CI) as 1.85 (1.51-2.25),1.39 (1.17-1.67),1.44 (1.24-1.67) and 1.46 (1.27-1.67),respectively.Conclusion The prevalence reported on diarrhea symptoms among adults from the rural areas was higher than the urban adults.Diarrhea was related to health-related habits,eating habits and regularity of taking physical exercises.

Study on the index system in evaluating the adult health literacy situation related to infectiousdisease in Beijing / 中华流行病学杂志

Objective To establish and assess a comprehensive index system on adult health literacy which related to infectious disease.Methods A multi-stage stratified sampling method was carried out among adults aged over 18 years,in Bcijing.A questionnaire survey was used to collect the information on adult health literacy situation related to infectious disease,with answers scored.Degrees of difficulty and difference together with confirmatory factor analysis were used to screen the indications from the questionnaires so as to establish a comprehensive index system.Methods as Cronbach a coefficient,split-half reliability,confirmatory factor analysis and cluster analysis methods were used to assess the reliability and validity of the index system.Results The sample size was 13 287 with valid questionnaires as 13 001.There were 30 indexes selected to establish the comprehensive index system on adult health literacy related to infectious disease.The Cronbach a coefficient was 0.777,and the split-half reliability was 0.609.Data from Confirmatory factor analysis revealed that each of the standardized regression coefficient was significant,and there were significant differences between the groups of being clustered by Q cluster analysis method (P＜0.001).9.9％ of the residents were classified as having enough knowledge on health.Conclusion The index system set for adult health literacy that related to infectious disease showed good reliability and validity thus could be used as a good tool to evaluate the levels of health literacy which related to infectious diseases,in Beijing.

Exposure to avian influenza virus and the infection status of virus among people breeding or butchering ducks in the suburb of Beijing / 中华流行病学杂志

Objective To understand the exposure and the infection status of virus among people engaging in breeding or butchering ducks in the suburb of Beijing.Methods People from six districts (Daxing,Fangshan,Huairou,Miyun,Shunyi,Tongzhou) who engaged in breeding or butchering ducks were studied and the status of infecting avian influenza virus was obtained by testing antibody level in serum.Information on demographic characteristics,status of regular exposure and exposure to sick or dead poultry were collected through a self-designed questionnaire.Results 1741people were involved in this study in which 313 (18.0％ ) were workers in duck-breeding enterprise,562 (32.3％) were workers in duck slaughterhouse,261 (15.0％) farmers were in individualsmall-scale duck farms,605 (34.7％) were farmers raising duck in backyard.Among farmers raising duck in backyard,the percentage of people whose ducks ever contacted with wild birds was higher than the other three groups (66.8％)(P＜0.05).Among farmers who bred their ducks in the backyard (35.2％) and those abattoir workers (31.3％ ),the percentage of people who had contacted ducks but not been vaccinated with avian influenza vaccine was higher than the other two groups (P＜0.05).Regarding the status on cleaning and disinfection among the studied farmers who had bred their ducks in the backyard,the percentage of people who had closer contact with ducks would clean the settings more than 4 times per month (8.8％) and disinfected those places more than 12 times per year (27.3％) but still lower than the other three groups (P＜0.05).Among those farmers who bred ducks in the backyard,the percentage of people who had ever touched duck with their hands was high (34.4％) (P＜ 0.05).Regarding exposure to sick or dead poultry,higher proportion was found among those who had ever closely contacted sick or dead poultry commercial duck raisers (36.1％) and individuals who raise large amount of ducks (36.0％).70.8％ of the individual duck raisers had never taken any protective measures when closely contacting the sick or dead poultry.Among 1741 samples,0 were positive to avian influenza virus H5 and H7 subtypes.12 were positive to H9 subtype (positive rate was 0.7％ ),in which 10 were farmers raising ducks in backyard (the positive rate of 1.7％ ).Differences between H9 subtype antibody positive rates difference in 4 population groups were statistically significant (x2=13.699,P＜0.05).Conclusion Farmers who bred their ducks in the backyard had greater risk of contracting the avian influenza.Individual duckers who raise ducks in large scale and the farmers who bred their ducks in the backyard were in lack of protective measures when contacting the sick or dead poultry.Our findings suggested that some intervention measures should be taken to reduce the risk of avian influenza infection.

Etiological detection of severe hand-food-mouth disease and related genetic characteristics of enterovirus type 71 infection in Beijing,2010 / 中华流行病学杂志

Objective To study the etiological detection on samples from severe hand-footmouth disease (HFMD) cases and the genetic characteristics of enterovirus type 71 (EV71) isolates lrom severe patients in Beijing,2010.Methods Real-time RT-PCR was used to detect EV71 and Coxsackievirus A16 (CoxA16) and RD cells were used to separate virus strains from samples.Homogeneity of EV71 isolated strains were also analyzed. Results Four hundred and fourty-two severe cases were detected and 253 were positive,taking up 57.24％ of the total (253/442).The overall positive detection rate on EV71 was 54.55％ (138/253),with CoxA16 as 5.93％(15/253),and with other enterovirus group was 39.53％(100/253).The nucleotide homogencity of VP1 within these 12 strains was 97.2％ 100.0％,and with Beijing strains in 2007-2010,Shandong strains in 2007 and Anhui Fuyang strains in 2008 and the Guangdong strains in 2008 as 94.0％-99.9％.Conclusion Severe HFMD cases were most oftenly caused by EV71 but less caused by CoxA16 or other cnterovirus.The HFMD in 2010 in Beijing was mainly caused by EV71 subgenotype C4a with 4 transmission chains.Twclve isolated EV71 strains had high homogeneity with strains isolated from severe cases in Anhui Fuyang in 2007.

Characteristics and related factors related to the resistance on antibiotics among group A streptococcus strains isolated from children in Beijing, during May and July 2011 / 中华流行病学杂志

Objective To analyze the characteristics of antibiotic resistance on group A streptococcus isolated from pediatrics in Beijing in 2011,to provide reference for clinical drug administration.Methods Strains of group A streptococcus were collected from the Departments of Pediatrics in 36 hospitals at different Districts of Beijing,from May to July 2011.Minimal inhibitory concentrations (MIC) with ten antibiotics of these isolates were tested by VITEK 2 Compact method.All the Susceptibility rate (S％),Intermediate rate (I％) and Resistance rate (R％) were calculated according to their MIC values.The macrolides resistant phenotype of group A streptococcus was detected by D-test.Results A total of 633 (19.1％) group A streptococcus strains were cultured from 3315 throat swabs.All the isolates were susceptible to penicillin,ampicillin,streptogramin,linezolid,tigecycline,vancomycin,while 96.5％ (611/633) of the isolates were susceptible to levofloxacin.A total of the 96.1％ (608/633) isolates exhibited resistance to erythromycin.The resistance rates to clindamycin and tetracycline were 79.3％ (502/633)and 93.7％ (593/633),respectively.A total of 9 different resistant patterns were observed,with the dominant patterns as:concomitant resistance to erythromycin,clindamycin and tetracycline (72.7％,460/633),followed by combined resistance to erythromycin and tetracycline (18.0％,114/633).The most commonly seen macrolide resistant phenotype was cMLS type (83.2％).In total,97 strains belonged to iMLS type and 5 strains to M type.Data through multivariate logistic regression analysis showed that factors as occupation and samples being collected from the sub-unban areas etc.were significantly associated with the resistance rates to tetracycline and the odds ratio (95％CI) as 2.43 (1.16-5.09) and 2.35 (1.47-3.73).Isolates collected from the sub-unban areas were significantly associated with resistance rates to clindamycin,with the odds ratio (95％CI) being 0.48(0.25-0.92).Conclusion All the isolates acquired from the Pediatrics Departments in Beijing were susceptible to penicillin and ampicillin.The high resistance rates of erythromycin,clindamycin and tetracycline resistance to group A streptococcus were observed,with the major resistant phenotype as cMLS.Factors as occupation and the collection site of samples were significantly associated with the resistance rates to tetracycline while the sites of sample collection were significantly associated with the resistance rates to clindamycin.

Multilocus variable-number tandem-repeat analysis for molecular subtypes of Shigella isolates in Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>Selecting variable-number tandem-repeat (VNTR) loci for different serogroups of Shigella spp to explore and establish multilocus variable-number tandem-repeat analysis (MLVA) method, in order to study the molecular characteristic of the isolated strains.</p><p><b>METHODS</b>Of the Shigella strains found by dysentery surveillance in Beijing from 2001 to 2009, 180 strains were selected for this study, according to the number and serotypes of the surveillant strains, at the ratio of 15%; including 50 strains of Shigella sonnei and 130 strains of Shigella flexneri. After screening the polymorphism of the 18 VNTR loci, 10 VNTR loci (sh1-sh10) were retained and constructed three groups of multi-PCR methods to detect all he 180 strains and analyze MLVA molecular subtypes using capillary segments.</p><p><b>RESULTS</b>A range of 2 to 11 alleles were found on the 10 VNTR loci among the 180 Shigella strains, with a diversity index value between 0.158 and 0.766. The 10 loci showed diversity in different serogroups, such as only one allele found in sh6 of Shigella flexneri, sh2 and sh3 of Shigella sonnei individually. The isolated 180 strains were divided into 84 MLVA subtypes, with a resolution ratio D value at 0.967 (95%CI: 0.956 - 0.978). The 130 strains of Shigella flexneri were divided into 63 subtypes, named as TF001-TF063; among which TF001, TF002 and TF 005 were the dominant subtypes, accounting to 17, 16 and 15 strains respectively. The 50 strains of Shigella sonnei were divided into 21 subtypes, named as TS001-TS021; among which TS002 (14 strains) and TS001 (7 strains) were the dominant subtypes.</p><p><b>CONCLUSION</b>MLVA subtyping method including 10 VNTR loci was preliminarily developed. The MLVA cluster analysis revealed that the subtypes of Shigella strains isolated in Beijing were diverse, and suggested the possibility of multiple-clone source.</p>

Study on types of M protein gene in group A streptococcus isolated from children in Beijing, 2011 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the distribution characteristics of the types of M protein gene (emm) in group A streptococcus (GAS) isolated from children in Beijing in the year 2011.</p><p><b>METHODS</b>During May to July in 2011, a total of 3315 patients who were diagnosed scarlet fever or pharyngeal infection by doctors in pediatric outpatient and emergency units of 36 hospitals, were selected as subjects. Their throat swab samples were collected and isolated the strains of GAS. Gene emm was then amplified and sequenced by PCR method, and the differences in types of gene emm between different populations and diseases were compared.</p><p><b>RESULTS</b>A total of 633 strains of GAS were isolated from the 3315 throat swab samples, 610 strains out of which were gene emm positive and were recruited in the study. Out of the 610 recruited strains, 448 (73.4%) were isolated from scarlet fever patients, the other 162 (26.6%) were isolated from pharyngeal infection patients; 397 (65.1%) were from urban, the other 213 (34.9%) were from suburb; 240 (39.4%) were from patients aging between 1 - 5 years old, the other 369(60.6%) were from patients aging 6 - 18 years old. A total of 8 types of gene emm (scarlet fever: 6 types, pharyngeal infection: 4 types) and 21 subtypes of gene emn (scarlet fever: 16 subtypes, pharyngeal infection: 10 subtypes) were identified. Three new subtypes were found in the study, naming emm1.63, emm12.62 and st5144.20. Among them, emm1.63 was found both in scarlet fever and pharyngeal infection patients, while emm12.62 and st5144. 20 were only found in pharyngeal infection patients. Among all the types of gene-emm, emm12 accounted for the highest percentage as 80.5% (491/610) and then followed by emm1 (18.0% (110/610)). Among all the subtypes, the dominant subtype was emm12.00, accounting for 69.0% (421/610), following by emm1.00 (16.9% (103/610)) and emm12.19 (6.1% (37/610)). All the above types and subtypes of gene emm were the most prevalent strains in scarlet fever patients and pharyngeal infection patients. Significant differences in the distribution of prevalent strains were observed among various aging patients and regions. The constituent ratios of emm1, emm1.00 and emm12.19 were higher in patients from suburb (emm1: 22.1% (47/213), emm1.00: 19.2% (40/213), emm12.19: 8.0% (17/213)) than those in urban areas (emm1: 15.9% (63/397), emm1.00: 15.6% (62/397), emm12.19: 5.0% (20/397)). The difference showed statistical significance (P < 0.05). The constituent ratio of emm1.00 was higher among patients aging 6-18 years old (19.2% (71/369)) than those aging 1 - 5 years old (13.3% (32/240)). The difference also showed statistical significance (χ(2) = 8.45, P < 0.05).</p><p><b>CONCLUSION</b>Among the types of gene emm in GAS isolated from children in Beijing in year 2011, the most prevalent two were emm12 and emm1, and the most prevalent emm subtypes were emm12.00, emm1.00 and emm12.19. A significant difference in their distribution between various aging patients and isolated places can be obviously found.</p>

Analysis on the etiological and molecular epidemiological characteristics of Vibrio parahaemolyticus in Beijing / 中华流行病学杂志

Objective To understand the etiological and molecular-epiderniological characteristics of Vibrio parahaemolyticus in Beijing.Methods Stool specimens from sporadic diarrheal patients were collected during April to December,2010.Culture and serotyping were used to detect the Vibrio parahaemolyticus from the 2118 specimens.All the positive strains were tested for drug sensitivity by Kirby-Bauer method.Real-time PCR was used to detect the existence of three virulence genes tlh,tdh and trh.Molecular typing on Vibrio parahaerrolyticus isolates was completed by pulsed field gel electrophoresis(PFGE).Results 114 out of the 2118 specimens were Vibrio parahaemolyticus positive,with the positive rate as 5.38％.114 isolates belonged to 23 serotypes,with the dominant (63.16％)serotype as O3:K6.Strains isolated from clinical manifestation patients were resistant to antibiotics-ampicillin and gentamicin,while with high sensitivity to amoxicillin,ceftriaxone,chloromycetin,imipenem,nalidixic acid and tetracycline.Virulence gene detection was positive to tlh for all the strains,but most to tdh,while only one strain to trh.The positive rate oftdh among O3:K6 strains(98.61％)was higher than that in those non-O3:K6 strains(85.71％)(P=0.0098).114 isolates were discriminated into 54 different PFGE patterns,while 72 O3:K6 strains into 34 patterns without the clustering characteristic.Conclusion Vibrio parahaemolyticus strains isolated from diarrheal patients in Beijing were dominated by O3:K6 strains,with stronger virulence.The positive rates of genes tlh and tdh were high.Vibrio parahaemolyticus strains showed high sensitivity to most antibiotics.The prevalent Vibrio parahaemolyticus strains in Beijing had various sources of clones.

Epidemiological characteristics and molecular typing of Salmonella in Beijing from 2008 to 2009 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the epidemiological characteristics and molecular phenotypes of Salmonella by pulsed-field gel electrophoresis (PFGE) in Beijing from 2008 to 2009.</p><p><b>METHODS</b>A total of one hundred thirty-seven isolates recovered from the WHO Global Salmonella Surveillance system and entero clinic surveillance system were identified by biochemical tests and serotyping. The related epidemiological informations were also analyzed. The isolates were further typed by PFGE.</p><p><b>RESULTS</b>The prevalence of Salmonella from 2008 to 2009 showed obvious seasonal character. High incidence occurred from June to September, and 64.1% (84/131) isolates were recovered in this period. Patients of 18 - 40 year-old were 46.1% (58/128) and 80 patients were male and 40 patients were female with the ratio of 1.57:1. These 137 Salmonella isolates belonged to 20 serotypes, including Enteritidis (46.7%, 64/137) and Typhimurium (17.5%, 24/137) as the dominant serotype. In total, 71 PFGE profiles were identified. Four PFGE patterns of S. Enteritidis isolates (JEGX01.CN0001, JEGX01.CN0003, JEGX01.CN0002, JEGX01.CN0019) and S. Typhimurium pattern of JPXX01.CN0001 were dominant patterns.</p><p><b>CONCLUSION</b>The prevalence of Salmonella from 2008 to 2009 showed distribution characteristics of sex, age and seasons. The numerous PFGE patterns of Salmonella showed diversity of these isolates and different clones existed in Beijing.</p>

The coverage rate and obstructive factors of influenza vaccine inoculation among residents aged above 18 years in Beijing from 2007 to 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To assess the coverage rate and obstructive factors of influenza vaccine inoculation among residents aged above 18 years in Beijing from 2007 to 2010.</p><p><b>METHODS</b>A total of 13 287 residents were recruited from six districts in Beijing. Information included demographic data, whether or not got vaccinated from 2007 to 2010, and the reasons for non-vaccination were collected using the questionnaires.</p><p><b>RESULTS</b>A total of 13 002 copies of questionnaires were valid and retrieved. The coverage rates of influenza vaccine inoculation among Beijing residents aged above 18 years between year 2007 and 2010 were 14.2% (1850/13 001), 18.0% (2345/13 002), 23.4% (3036/13 002) and 18.6% (2416/13 002), respectively. The 4-year adherent inoculation rate was 9.1% (1186/13 001). The coverage rates in the subjects aged over 60 years, less educated, medical-practitioner or retired were relative higher, with the 4-year adherent inoculation rate at 24.4% (614/2521), 24.4% (94/386), 14.6% (47/323) and 19.0% (386/2036). The factors induced non-vaccination among residents included "I don't think I am very likely to catch the flu" (51.2%, 6002/11 722), "I have no spare time to get vaccinated" (18.3%, 2145/11 722), "The influenza vaccination is too expensive" (15.8%, 1852/11 722), "I am afraid of the side-effects" (15.2%, 1782/11 722), "I don't believe the vaccine is effective enough" (12.9%, 1512/11 722), "I don't think influenza is a serious disease" (10.1%, 1184/11 722), "I have the specific contraindications" (7.3%, 856/11 722), and "I have never heard influenza vaccination before" (5.2%, 610/11 722). With regard to the reasons for non-vaccination, significant differences were found among subjects with different educated levels, different ages and different occupations. The proportion of thoughts "I don't think I am very likely to catch the flu" among the residents in five educational levels (illiterates or semi-illiterates, primary school, junior middle school, senior middle school and college or above) were 28.6% (83/289), 39.8% (473/1188), 49.1% (1642/3341), 50.7% (1719/3392) and 51.3% (1794/3501) respectively, with a significant statistical difference (χ(2) = 98.33, P < 0.01).</p><p><b>CONCLUSION</b>The coverage rates of influenza vaccine inoculation were low among residents aged above 18 years from 2007 to 2010 in Beijing. The main reasons for non-vaccination included lack of information about risk in influenza infection and its severity to health, and anxiety about vaccine safety and effectiveness.</p>

Comparisons of epidemiological and clinical characteristics in children with hand-foot-mouth disease caused by Enterovirus 71 and Coxackievirus A16 / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To compare the differences of epidemiological and clinical characteristics in children with hand-foot-mouth disease (HFMD) caused by Coxsackievirus A16 (CA16) and Enterovirus 71 (EV71).</p><p><b>METHODS</b>The samples of vesicle fluid and throat swabs of 108 children with HFMD were collected and detected for enterovirus by RT-PCR. The clinical data of children with EV71 and CA16 infection were retrospectively reviewed and compared.</p><p><b>RESULTS</b>The total positive rate of enterovirus was 97.2% (105/108). Of the 105 cases, 56 cases were positive for EV71 (51.9%), 39 cases were positive for CA16 (36.1%), 2 cases were positive for other enterovirus (1.9%), and 8 cases were co-infected by EV71 and CA16 (7.4%). There were no significant differences in age and sex between EV71 and CV16 infected cases. The univariate analysis showed that the incidences of herpes of mouth, erythra of knees, and nose running in children infected by CA16 were higher than in those infected by EV71. The multivariate logistic regression analysis showed that the HFMD children who had erythra of knees had higher probability of CA16 infection.</p><p><b>CONCLUSIONS</b>EV71 should be considered as the pathogen in children with HFMD who have no herpes of mouth, erythra of knees, and nose running.</p>

Pandemic influenza A (H1N1) virus infection factors among healthcare workers - a case-control study / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore factors related to pandemic influenza A (H1N1) virus infection among healthcare workers.</p><p><b>METHODS</b>H1N1 influenza confirmed cases of health workers in hospital of Beijing from Aug 30th 2009 to Jan 31st 2010 were included. A 1:4 matched case-control study was conducted with 54 healthcare workers who were infected by influenza A(H1N1) virus and 216 matched controls who were not infected. Face-to-face interview with questionnaires was used to collect information of work and family aspects of the study participants. Conditional logistic regression was used to analyze the H1N1 infection factors.</p><p><b>RESULTS</b>The age was 29.6 ± 7.4 years old and male subjects accounted for 17.4% (47/270). There were 5.6% (3/54) and 34.4% (74/216) of the cases get the influenza A (H1N1) vaccine immunization separately in the case group and control group. Among 18.5% (10/54) and 40.1% (88/216) of the cases and controls used high protection level masks during the epidemic. Besides, 33 (61.1%)and 161 (74.5%) cases lengthening the time of mask wearing separately. There were 13 (24.1%) and 85 (39.4%) cases using disposable tissue to clean hands in the case group and control group, 24 (44.4%) and 46 (21.3%) cases feel they were much easier to get infected in respiratory disease than others based on experience in the case and control group. Univariate analysis showed that factors such as using disposable tissue to clean hands (OR = 0.15, 95%CI = 0.04 - 0.57), lengthening the time of mask wearing (OR = 0.43, 95%CI = 0.20 - 0.92), using high protection level masks (OR = 0.26, 95%CI = 0.11 - 0.58), getting influenza A (H1N1) vaccine immunization (OR = 0.04, 95%CI = 0.01 - 0.32), much easier to get infected in respiratory disease than others based on experience (OR = 2.85, 95%CI = 1.44 - 5.62), were all associated with influenza A (H1N1) infection. Results of multivariate logistic regression analysis showed that variables such as history of influenza A (H1N1) virus immunization (OR = 0.18, 95%CI = 0.06 - 0.51), using high protection level masks (OR = 0.05, 95%CI = 0.01 - 0.35), much easier to get infected in respiratory disease than others based on experience (OR = 3.69, 95%CI = 1.58 - 8.63) were all correlated to influenza A (H1N1) infection.</p><p><b>CONCLUSIONS</b>Factors such as history of influenza A (H1N1) vaccine immunization, using high protection level masks and improving respiratory health can protect healthcare workers from infection of influenza A (H1N1).</p>