High prevalence of Babesia microti in small mammals in Beijing.

BACKGROUND: Babesiosis is an emerging tick-borne zoonotic infectious disease. Babesia microti is responsible for most cases of human babesiosis globally. It is important to investigate the prevalence of B. microti in the mammalian host population of a specific region in order to elucidate mechanisms of pathogen transmission and to define geographic areas where humans face the greatest risk of exposure. The aim of this study is to understand the prevalence and genotypes of B. microti in the small mammals that are found in Beijing, China. METHODS: We trapped small mammals from all of the 16 urban, suburban, and outer suburban districts of Beijing during the years 2014, 2017 and 2018. Genomic DNA was extracted from the heart tissues individually and the Babesia 18S rRNA gene was detected by PCR. The genotypes of B. microti were identified based on sequence alignments and phylogenetic analysis. The morphology of the parasites was observed under light microscopy. The risk factors were analyzed statistically based on both univariate analyses and multivariate logistic regression. RESULTS: A total of 1391 small mammals were collected. Positive infection of B. microti was detected in 12.1% (168/1391) of small mammals from 15 out of the 16 districts. Both Kobe-type and U.S.-type B. microti, accounting for 9.5% and 2.7%, respectively, were identified. Classic diverse morphologic forms of B. microti were observed. Specific types of ecological habitats including shrub areas, broad-leaved forest, and cropland were revealed to be risk factors associated with B. microti infection. CONCLUSIONS: This study demonstrated the wide prevalence of B. microti infection in eight species of small mammals in Beijing, with Kobe-type more prevalent than U.S.-type. This study provides fundamental information for the development of informed prevention and control measures by public health authorities; the data gathered indicates a need for further monitoring of both clinical diseases in individuals presenting with babesiosis-like symptoms, as well as the infection status of ticks in high risk areas.

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.

Evaluation of four candidate VNTR Loci for genotyping 225 Chinese clinical Mycobacterium tuberculosis complex strains.

OBJECTIVE: To evaluate four candidate variable number tandem repeat (VNTR) loci for genotyping Mycobacterium tuberculosis complex strains. METHODS: Genomic sequences for two M. tuberculosis strains (CCDC5079 and CCDC5180) were generated, and using published sequence data, four candidate VNTR loci were identified. The VNTRs were used to genotype 225 Chinese clinical M. tuberculosis complex strains. The discriminatory power of the VNTRs was evaluated using BioNumerics 5.0 software. RESULTS: The Hunter-Gaston Index (HGI) for BJ1, BJ2, BJ3, and BJ4 loci was 0.634, 0.917, 0.697, and 0.910, respectively. Combining all four loci gave an HGI value of 0.995, thus confirming that the genotyping had good discriminatory power. The HGI values for BJ1, BJ2, BJ3, and BJ4, obtained from Beijing family strain genotyping, were 0.447, 0.878, 0.315, and 0.850, respectively. Combining all four loci produced an HGI value of 0.988 for genotyping the Beijing family strains. We observed unique patterns for M. bovis and M. africanum strains from the four loci. CONCLUSION: We have shown that the four VNTR loci can be successfully used for genotyping M. tuberculosis complex strains. Notably, these new loci may provide additional information about Chinese M. tuberculosis isolates than that currently afforded by established VNTR loci typing.

[Epidemiological characteristics and molecular typing of Salmonella in Beijing from 2008 to 2009].

OBJECTIVE: To study the epidemiological characteristics and molecular phenotypes of Salmonella by pulsed-field gel electrophoresis (PFGE) in Beijing from 2008 to 2009. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Estimation on the real number of novel influenza A (H1N1) cases, Beijing, 2009].

OBJECTIVE: To estimate the real number of novel influenza A (H1N1) infection in Beijing, 2009. METHODS: A multiplier model (Impact 2009 v 1.0 software) based on Monte Carlo approach was used to estimate the real number of novel influenza A (H1N1) based on the number of influenza-like illness (ILI) cases, novel influenza A (H1N1) positive rate among ILI cases and rate on clinical visit of ILIs in secondary and tertiary hospitals. RESULTS: There were 1.80 million (90%CI: 1.46 - 2.30) estimated novel influenza A (H1N1) cases in 2009 in Beijing with the rate of infection as 11.0%. One reported case would represent 167 real infections. The highest age groups of infection were 0 - 4 years and 5 - 14 years, being 32.5% and 33.3%, respectively. CONCLUSION: Laboratory-confirmed infections with novel influenza A (H1N1) only represented a fraction of the total cases in a population, suggesting that it was imperative to estimate the real number of novel influenza A (H1N1) infection.

[Outbreak of acute hemorrhagic conjunctivitis in Beijing City in 2007 caused by coxsackievirus A24 variant: molecular identification and phylogenetic analysis].

In 2007, an outbreak of acute hemorrhagic conjunctivitis (AHC) occurred in Beijing. In order to identify the etiology of this outbreak, 57 eye conjunctival swabs were collected from 57 outpatient patients, and detected for adenovirus, human enterovirus 70 (HEV70) and Coxsackievirus A24 variant (CVA24v) genes by using RT-PCR or PCR methods. The results showed that 38 were positive for CVA24v, the positive rate was 66.7%, but none was positive for HEV70 and adenovirus, showing that this outbreak was caused by CVA24v. 9 viral isolates were obtained from 57 clinical specimens by using viral isolation method, and all were identified as CVA24v by molecular typing method. All 9 CVA24v isolates were performed by VP1 sequencing, the results showed that except for strain 0744/BJ/CHN/2007, the variability at nucleotide acid level and amino acid level among other 8 CVA24v were relatively low, and the homologies were more than 99.6% and 100.0%, respectively; the homologies of nucleotide acid and amino acid between strain 0744/BJ/CHN/2007 and other 8 CVA24v were 96.8%-97.2% and 99.7%, respectively. Phylogenetic analysis of 9 CVA24v revealed that they represented the Clade 4 and Clade 5 in Group I, showed that this outbreak was caused by at least 2 viral transmission chains. Comparing to 3C region of CVA24v frequently used before, VP1 region was considered as the most rigorous target for molecular epidemiology study of CVA24v. To enhance the research of sero-epidemiology and molecular epidemiology of CVA24v and to know the genetic characterizations and molecular evolution of CVA24v are most important to prevent and control the outbreaks of AHC in China.

[Etiological analysis of enteric infectious diseases during Beijing Olympic Games].

OBJECTIVE: To understand pathogen patterns of enteric infectious diseases and its impact on this pattern due to aggregation of a great deal of foreign visitors during Beijing Olympic Games. METHODS: The diarrheal patient's rectal swabs and stool specimens were collected from Olympic stadium and hospitals of four districts, including Dongcheng, Xicheng, Haidian and Chaoyang. Enteric multiple pathogens were detected from the total 45 specimens. The culture method was used for the enteric bacteria, ELISA and RT-PCR for the enteric viruses. Molecular typing of Salmonella Enteritidis isolation was completed by PFGE. RESULTS: It was found that 26 out of 45 cases were positive with 57.8 percent for pathogen detection, and 24 were identified as enteric pathogenic bacteria, including Vibrio parahaemolyticus, Salmonella, diarrheagenic Escherichia coli and Campylobacter jejuni, two as norovirus. There were mixed infections of two pathogenic bacteria for three cases. Ten kinds of pathogens were detected from foreign cases, while five kinds from Chinese cases. A total of 5 PFGE patterns were identified in 10 Salmonella Enteritidis isolates from national and foreign diarrheal cases, which were concentrative in some extent. CONCLUSION: Vibrio parahaemolyticus, Salmonella, diarrheagenic Escherichia coli and Campylobacter jejuni were found to be the primary bacterial pathogens during the Olympic Games. Enteric virus infection existed in summer diarrhea.

[Investigation on the source of the first human of avian influenza A (H5N1) case in Beijing].

OBJECTIVE: To investigate the source of the first human case of avian influenza A (H5N1) infection in Beijing. METHODS: Interviewing the relatives of the case and other key persons, collecting and detecting samples of related biological, epidemiological and environmental data of the case were conducted. Later, the infection source was thoroughly investigated. RESULTS: The case ever contacted a slaughtered duck 5 days prior to the onset of illness, and the duck was bought from a stall of a wet market in Yanjiao area of Hebei province. Ten environmental samples were collected in this stall and the neighboring stall of the market. Another 6 samples were tested positive for H5N1 virus by PCR method, with 5 virus strains isolated. The whole-genome sequencing indicated that the amino acid homology between the H5N1 virus strains from the environment and the virus isolated from the case reached 99.8% - 100%. CONCLUSION: From both epidemiological and virological evidence, it was proved that the first human case of avian influenza A (H5N1) infection in Beijing was infected by a duck that carrying H5N1 virus the case contacted 5 days proceeding the onset of illness.

[Study on the epidemiologic characteristics of norovirus infection in Beijing].

OBJECTIVE: To investigate the epidemiological characteristics of norovirus infection in Beijing. METHODS: Both outbreaks and sporadic cases of acute gastroenteritis were studied through questionnaires while the stools of patients were collected. Noroviruses were detected by ELISA or RT-PCR, and PCR products were cloned and sequenced. RESULTS: Eight outbreaks were reported between November 2006 and March 2007, which were confirmed as nosocomial infections. A total of 158 positive cases were detected among 409 sporadic cases of acute virus gastroenteritis with a positive rate of 38.63%. The highest positive rate (55.00%) was found in group aged from 40 to 44, while the lowest positive rate (21.74%) fell into groups aged from 55 to 59. The positive cases aged from 6 months to 91 years with the mean age of 40 years old including 84 males and 74 females. Data from sequence analysis showed that norovirus epidemic strains helonged to the GII/4 variants in Beijing, which were almost identical to the variants causing epidemics both in the Netherlands and in Japan. CONCLUSION: Norovirus was important, causing virus-borne diarrhea between 2006 and 2007 in Beijing, and the epidemic strains were consistent with those isolated from both the Netherlands and Japan in 2006.

[Metabolic syndrome strongly linked to stroke in Chinese].

OBJECTIVE: To assess the association of the metabolic syndrome with stroke in Chinese using the definition of ATP III, and revised definition according to Chinese criteria for abdominal obesity. METHODS: Multi-center case control study, 1934 first-ever-stroke patients (Atherothrombosis, lacunar infarction, and intracerebral hemorrhage) aged 30 to 74 years were sequentially recruited. And 1839 age, gender and geographically matched subjects were included as controls. RESULTS: The prevalence of metabolic syndrome defined by either ATP III or Chinese criteria was significantly increasing in patients with lacunar infarction, cerebral atherosclerosis, or intracerebral hemorrhage than control subjects. After age- and sex-adjusted and further adjusted age, sex, total cholesterol, smoking, drinking, and education levels, the metabolic syndrome defined by ATP III criteria was associated with a 2.7 to 4.3 fold and 2.5 to 4.0 fold higher risk of the three stroke subtypes, respectively. CONCLUSION: the metabolic syndrome defined by ATP III and revised according to Chinese criteria of abdominal obesity was positively associated with the risk of stroke in our case control study. This study underscores the need for well-designed prospective study in Chinese to give further evidence to the link between metabolic syndrome and stroke.

[Alpha-adducin gene G/W460 polymorphism is associated with intracerebral hemorrhage in Chinese].

OBJECTIVE: To explore the association between alpha-adducin (ADD1) G/W460 and intracerebral hemorrhage (ICH) in Chinese. METHODS: Samples of peripheral blood were collected from 456 patients with ICH diagnosed by CT or MRI from 7 clinical centers in China and 454 age, sex, and geographically matched subjects as controls. The ADD1 G/W460 polymorphism was detected by PCR. Information about prior exposure to various potential risk factors was collected by questionnaire survey. RESULTS: The distribution of ADD1gene G460W polymorphisms in the ICH patients and controls were in agreement with the Hardy-Weinberg proportion. The prevalence of 460W allele among ICH cases was 82.2%, higher than that in the controls (76.0%, crude odds ratio, 1.46; 95% CI, 1.05 to 2.05). The ADD1 460W allele was still significantly associated with ICH after adjustment for hypertension and other ICH putative risk factors (adjusted odds ratio, 1.38; 95% CI, 1.01 to 1.88). CONCLUSION: Alpha-adducin gene G/W 460 polymorphism is significantly associated with the risk of ICH. This association does not appear to be mediated by established ICH risk factors, specifically hypertension status.