Biomedical subjects
Publications and source records attributed to Xiong He.
A suspicious meningococcal meningitis death case was reported to the Beijing CDC. The blood specimen was analyzed via multi-PCR and MLST. 6 isolates from close contacts were analyzed via PFGE and MLST. According to the results of the above analyses, the cause of this case was identified as a serogroup A Neisseria meningitidis, which, in terms of sequence typing, belonged the ST7 group.
OBJECTIVE: To study the pathogens of meningococcal meningitis (MM) in Beijing, 2005. METHODS: Blood and cerebrospinal fluid specimens from MM patients were detected by polymerase chain reaction. Bacterial strains were analyzed by pulsed-field gel electrophoresis and multilocus sequence typing. RESULTS: 7 of the blood and 5 of cerebrospinal fluid specimens showed positive results. 105 of the Neisseria meningitides strains were isolated from the specimens of patients, close contacts and healthy carriers. Serogroup A and C Neisseria meningitides strains shared the same patterns of pulsed-fieldgel electrophoresis, respectively. The sequence type of serogroup A Neisseria meningitides belonged to ST7 while the sequence type of serogroup C Neisseria meningitides belonged to ST4821. CONCLUSION: Patients suffered from meningococcal meningitis were caused by serogroup A (ST7) and C (ST4821) Neisseria meningitides in Beijing, 2005.
Following the requirements of the "National survey on the current status of the major human parasitic diseases", the investigation was conducted in June-October 2002 in 5 districts (counties) of Beijing with a sample of 7912 people. The overall prevalence rate of intestinal parasites was 2.9%, significantly lower than the result from the first survey in 1988-1989 (34.8%) (chi2=3 227.45, P<0.05), revealing that intestinal parasitic infections are not an important risk for people in Beijing Municipality in general.
OBJECTIVE: To study the potential risk factors for severe acute respiratory syndromes (SARS)-related deaths in Beijing. METHODS: Epidemiological data were collected among the confirmed SARS patients officially reported by Beijing Centers for Disease Control and Prevention (BCDC), and information was also supplemented by a follow-up case survey. Chi-square test and multivariate stepwise logistic regression analysis were performed. RESULTS: Old age (over 60 years) was found to be significantly associated with SARS-related deaths in the univariate analysis. Also, history of contacting SARS patients within 2 weeks prior to the onset of illness, health occupation, and inferior hospital ranking as well as longer interval of clinic consulting (longer than 1 day) were the risk factors for SARS-related deaths. Multivariate stepwise logistic regression analysis found four risk factors for SARS-related deaths. CONCLUSION: Old age (over 60 years) is the major risk factor for SARS-related deaths. Moreover, hospital health workers, the designated hospitals for SARS clinical services and the interval of consulting doctors (less than 1 day) are protective factors for surviving from SARS.
The aim of this study was to characterize the molecular features of serogroup C Neisseria meningitidis strains circulating in Beijing, China. Twenty out of 23 strains belonged to ST 4821. The causative serosubtype for meningococcal meningitis was P1.12-1,16-8. All of the strains expressed class 3 PorB protein. Among the five pulsed-field gel electrophoresis patterns observed, pattern III predominated.
OBJECTIVE: To describe the specific features of the contact history of probable cases of severe acute respiratory syndrome (SARS) in Beijing. METHODS: Data of SARS cases notified from the Beijing Municipal Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. All the data were analyzed by descriptive epidemiology. RESULTS: (1) The number of probable cases with contact history was significantly higher than the excluded cases. (2) The proportion of probable cases with contact history descended with epidemic development, but this situation did not occur in health care workers (HCWs). (3) The fatality rate of probable cases with contact history was significantly higher than the cases without contact history (OR = 1.489). (4) The proportion of probable cases with contact history was 85.86% among health care workers, which was significantly higher than that of non-health care workers (85.86% v.s. 56.44%, OR=4.69). CONCLUSIONS: (1) The susceptible persons with contact history may not get infected, and the contact history is just a sufficient condition of infecting SARS; (2) There are 3 conceivable reasons for the descending trend of the proportion in probable cases with contact history; (3) The contact history is one of the risk factors of the death of SARS cases; (4) The risk of contacting with SARS among health care workers is approximately 5 times higher than that of non-HCWs.
OBJECTIVES: To assess the impacts of public health interventions on the outbreak of SARS in Beijing by analyzing the intervals between symptom onset, hospital admission and notification of its cases. METHODS: Data of SARS cases reported from the Beijing Municipal Centers for Disease Prevention and Control (BCDC) were collected and analyzed by descriptive epidemiology. RESULTS: In the early epidemic period, the intervals between the disease onset and the hospital admission seemed irregular, so was the intervals between the hospital admission and the notification. After the middle ten days of April, the intervals turned out to be more regular, and the disordered situation in terms of the hospital admission and the case notification was gradually brought under control. CONCLUSIONS: Public health interventions against SARS has revealed positive impacts on SARS control program in Beijing. The timing and sensitivity of epidemic information reporting systems has been greatly improved in Beijing as a result of successful fight against this disease.
OBJECTIVE: To describe the case fatality rate of SARS in Beijing. METHODS: Data of SARS cases notified from Beijing Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. The data were analyzed by rate calculation. RESULTS: The case fatality rate of SARS in Beijing was 7.66%, and had an ascending trend while the age of cases was getting older, and a descending trend while the epidemic development. The case fatality rate in Beijing was lower than that in other main epidemic countries or regions. CONCLUSIONS: The risk of death increases with the increment of age of SARS patients. Beijing is successful in controlling and treating SARS.
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.
BACKGROUND: Severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) is the principal etiologic agent of SARS. We analyzed serum samples obtained from 623 patients with SARS in Beijing, to determine whether infection with SARS-CoV can elicit neutralizing antibodies (NAbs). METHODS: We developed a highly sensitive and safe neutralization assay using the SARS-CoV pseudotyped virus and used this assay to determine the titers of the NAbs in serum samples from patients with SARS. RESULTS: We found that 85.9% of serum samples contained NAbs against SARS-CoV and that most of the NAb activities could be attributed to immunoglobulin G. The NAbs became detectable first at 5-10 days after the onset of symptoms, and their levels peaked at 20-30 days and then were sustained for >150 days. The serum samples could neutralize the pseudotype particles bearing the spike glycoproteins from different SARS-CoV strains, suggesting that the NAbs to SARS-CoV were broadly reactive. CONCLUSIONS: NAbs to SARS-CoV are broadly elicited in patients with SARS and, according to their kinetics, may correlate with viral load during the early stages of the disease. These results suggest that it is possible to develop effective vaccines against SARS and that NAbs provide a potential strategy for treating patients with SARS.
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.
Superspreading events were pivotal in the global spread of severe acute respiratory syndrome (SARS). We investigated superspreading in one transmission chain early in Beijing's epidemic. Superspreading was defined as transmission of SARS to at least eight contacts. An index patient with onset of SARS 2 months after hospital admission was the source of four generations of transmission to 76 case-patients, including 12 healthcare workers and several hospital visitors. Four (5%) case circumstances met the superspreading definition. Superspreading appeared to be associated with older age (mean 56 vs. 44 years), case fatality (75% vs. 16%, p = 0.02, Fisher exact test), number of close contacts (36 vs. 0.37) and attack rate among close contacts (43% vs. 18.5%, p < 0.025). Delayed recognition of SARS in a hospitalized patient permitted transmission to patients, visitors, and healthcare workers. Older age and number of contacts merit investigation in future studies of superspreading.
OBJECTIVE: To examine the characteristics of cases excluded from severe acute respiratory syndrome (SARS) and the reasons for exclusion. METHODS: 2071 probable or suspected cases excluded from SARS between March and June, 2003 were analyzed. RESULTS: Two-thirds of the excluded cases were males. Construction workers, students and retired people ranked top three in all the occupation categories. Three peaks appeared in the dates of exclusion, and the most obvious one was from June 7 to June 13. There were two peaks in the distribution of time period from onset to exclusion, one was six to ten days and the other was forty-eight to fifty-two days after onset. Patients with history of close contact were more likely to be excluded within fifty days after onset than those without close history of contact. Pneumonia, common cold and lung infection were the leading causes for correction in the 1211 excluded cases. CONCLUSION: Study on the diagnosis and differential diagnosis should be emphasized.
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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.