Lyme Borreliosis-associated Risk Factors in Residents of Beijing Suburbs: a Preliminary Case-control Study.

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.

[Prevalence of hepatitis B in Chaoyang district, Beijing in 2010].

OBJECTIVE: To study the prevalence of hepatitis B infections and carrier status among general population in Chaoyang district, Beijing in 2010. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

[Study on the cellular and humoral immunity effect of recombinant Chinese hamster ovary cell hepatitis B vaccine in adults].

OBJECTIVE: To evaluate the cellular and humoral immunity effect of 10 µg and 20 µg recombinant Chinese hamster ovary (CHO) cell hepatitis B vaccine in adults by randomized double-blind controlled trials. METHOD: A total of 642 adults aged 18 - 45 years old, non-vaccinated against hepatitis B, and hepatitis B five blood indicators negative were selected as the study subjects. The study subjects were randomly divided into two groups and each group had 321 subjects. The subjects were given 10 µg and 20 µg recombinant CHO hepatitis B vaccination respectively by 0, 1st, 6th month schedule. Blood sample was collected from each study subject one month after the second dose vaccination. The anti-HBs level was detected by Abbott chemiluminescence detection method (I2000) to evaluate humoral immunity status. Of all the study objects, 153 cases were randomly selected by the Excel random function. Their blood samples were collected and Lymphocyte were separated to detect the IL-4 and IFN-γ levels in vitro by enzyme-linked immunospot (ELISPOT) method to evaluate the cellular immunity status. RESULTS: The anti-HBs seroconversion rates in 10 µg and 20 µg dose group were 88.8% (285/321) and 95.3% (306/321) respectively, and 95%CI were 85.4% - 92.2% and 93.0% - 97.6% respectively. The spot forming cell (SFC) of IL-4 of the 20 µg-dose group (x(-) = 20.31) were significantly higher than the 10 µg-dose group (x(-) = 8.19, t = 3.27, P < 0.01). With the increasing of anti-HBs titer, the SFC of IL-4 also went up significantly. There was a positive correlation between SFC of IL-4 and anti-HBs (Spearman correlation coefficient = 0.538, P < 0.0001). No significant difference was found for IFN-γ SFC in two groups (10 µg group: x(-) = 1.49; 20 µg group: x(-) = 0.86; t = 1.83, P > 0.05). CONCLUSION: The humoral and cellular immune effects of 20 µg recombinant CHO hepatitis B vaccine are better than that of the 10 µg recombinant CHO hepatitis B vaccine.20 µg recombinant CHO hepatitis B vaccine should be chosen as the adult's hepatitis B prevention vaccine.

[Study on the immuno-effects and influencing factors of Chinese hamster ovary (CHO) cell hepatitis B vaccine among adults, under different dosages].

OBJECTIVE: To evaluate the immuno-effect and related influencing factors on 10 µg and 20 µg Chinese hamster ovary (CHO) cell hepatitis B vaccine, using the randomized double-blind controlled trials in adult population. METHODS: A total of 642 adults aged 18 - 45 years old, non-vaccinated against hepatitis B, and negative on five blood indicators for hepatitis B, were selected as the study objects from four districts in Beijing. The study objects were randomly divided into two groups, and then accepted 10 µg and 20 µg recombinant CHO hepatitis B vaccination by 0 - 1 - 6 month schedule. Influencing factors were investigated by means of questionnaire. Blood samples were collected one month after the third dose of vaccination. Anti-HBs level was detected by Abott chemiluminescence detection method. For the anti-HBs negative person, fluorescent quantitative PCR method was used to find out if the person had been infected with HBV. Logistic regression analysis was used to find out the influencing factors of anti-HBs seroconversion on every studied subject. RESULTS: The anti-HBs seroconversion rates on 10 µg and 20 µg dose groups were 88.8% (95%CI: 85.4% - 92.2%) and 95.3% (95%CI: 93.0% - 97.6%) respectively. Taking the anti-HBs level < 100 mIU/ml as the low/non-response standard, the low response and non-response rates were 34.3% and 17.4% respectively. The geometric mean titers (GMT) of anti-HBs were 173.42 mIU/ml for the 10 µg dose group and 588.51 mIU/ml for the 20 µg dose group. Data from the Multivariate analysis showed that:diabetes, spouses infected with hepatitis B virus and old age were unfavorable factors for anti-HBs Seroconversion. 20 µg dose of the vaccine was conducive to seroconversion. CONCLUSION: 20 µg CHO hepatitis B vaccine seemed better than 10 µg CHO hepatitis B vaccine while many factors need to be taken into account for evaluation on hepatitis B vaccines.

[A sero-epidemiologiecal study on hepatitis B among general population in Beijing].

OBJECTIVE: To explore the serological infection rate of hepatitis B virus (HBV) in general population aged over one year old in Beijing and to provide information for control and prevention of the disease. METHODS: A multistage randomized cluster sampling was carried out in general population of Beijing, aged over one year old. Every study subject's hepatitis B immunization history and main risk factors were investigated through questionnaire. Venous blood samples were collected and then tested for five hepatitis B serological antigens and antibodies by means of Abbott Microparticle Enzyme Immunoassy method. RESULTS: The prevalence rates of HBsAg, anti-HBs, anti-HBc and total HBV infection rate were 3.49% (95% CI:2.99-3.99), 37.79% (95% CI: 36.46-39.12), 35.04% (95% CI: 33.72-36.35) and 35.09% (33.78-36.40) respectively. The age standardized rates were 3.02% ,42.47% ,26.86% and 26.90% respectively. CONCLUSION: Achievement in hepatitis B control and prevention was made in Beijing since the prevalence rate of hepatitis B surface antigen had been below 1% for children aged less than 5 years old. As for the general population, the prevalence rate of hepatitis B surface antigen had reduced to

[A study on the sero-epidemiology of hepatitis B in Chinese population aged over 3-years old].

OBJECTIVE: To better understand and measure the impact from immunization activities over the last 10-years, we conducted a sero-epidemiological study using the remaining blood samples of a nationwide survey on Nutrition and Health in Chinese residents, in 2002. METHODS: HBsAg, anti-HBs and anti-HBc in blood samples were tested using enzyme-linked immunosorbent assay(ELISA) reagents and revised by solid phase radioimmunoassay and Abbott ELISA reagents. RESULTS: Among population older than 3 years, the prevalence rates of HBsAg, anti-HBs and hepatitis B virus(HBV) infection were 9.09%, 37.48% and 50.04% but for children between 3 and 12 year olds, they were 5.03%, 45.33% and 29.10% respectively. Among population older than 3 years, the rates of HBsAg and HBV infection in urban area were 4.61% and 43.51%, but the rates in rural area were 9.41% and 56.77% respectively while for children from 3-years to 12-years old, they rates were 2.10%, 20.45% in urban area and 8.25%, 39.22% in rural areas, respectively. CONCLUSION: Results revealed that since the hepatitis B vaccine was introduced into the expanded program on immunization(EPI) from 1992, the prevalence rates of HBsAg and HBV infection, especially in the children from 3 to 12 years of age, had obviously declined, suggesting that some changes had happened in the epidemic characters of hepatitis B in China.

Risk factors for SARS among persons without known contact with SARS patients, Beijing, China.

Most cases of severe acute respiratory syndrome (SARS) have occurred in close contacts of SARS patients. However, in Beijing, a large proportion of SARS cases occurred in persons without such contact. We conducted a case-control study in Beijing that compared exposures of 94 unlinked, probable SARS patients with those of 281 community-based controls matched for age group and sex. Case-patients were more likely than controls to have chronic medical conditions or to have visited fever clinics (clinics at which possible SARS patients were separated from other patients), eaten outside the home, or taken taxis frequently. The use of masks was strongly protective. Among 31 case-patients for whom convalescent-phase (>21 days) sera were available, 26% had immunoglobulin G to SARS-associated coronavirus. Our finding that clinical SARS was associated with visits to fever clinics supports Beijing's strategy of closing clinics with poor infection-control measures. Our finding that mask use lowered the risk for disease supports the community's use of this strategy.

[Analysis on the epidemiological features and the transmission of an imported severe acute respiratory syndrome case in Beijing].

OBJECTIVE: To explore the characteristics of severe acute respiratory syndrome (SARS) transmission in the population base on analyzing the first imported case and the chains of transmission. METHODS: For the first imported SARS case and cases who were transmitted by the index case, epidemiological investigations were conducted using the guidelines for surveillance and case investigation issued by the Ministry of Health. Data as the date of onset of symptoms, date of hospitalization, contact history etc. for each of the cases and their close contacts were collected and analyzed. RESULTS: The first imported SARS case introduced to Beijing had infected 9 people within the family and at the hospital, with two of whom died of the same disease. The incubation period for that index case was 4 days, and that for the cases considered to be the secondary and tertiary generations were 7 and 8 days, respectively. The shorter the incubation period, the longer the fever would last and clinically more severe. CONCLUSION: One of the epidemiological characteristics of SARS in Beijing was noticed that the disease clustered in families and hospitals. Infection through droplets and close contact has been viewed as the primary mode of transmission.