[Analysis on the secondary attack rates of SARS-CoV-2 Omicron variant and the associated factors].

Objective: To evaluate the secondary attack rates of the SARS-CoV-2 Omicron variant and the associated factors. Methods: A total of 328 primary cases and 40 146 close contacts of the SARS-CoV-2 Omicron variant routinely detected in local areas of Jiangsu Province from February to April 2022 were selected in this study, and those with positive nucleic acid test results during 7 days of centralized isolation medical observation were defined as secondary cases. The demographic information and clinical characteristics were collected, and the secondary attack rate (SAR) and the associated factors were analyzed by using a multivariate logistic regression model. Results: A total of 1 285 secondary cases of close contacts were reported from 328 primary cases, with a SAR of 3.2% (95%CI: 3.0%-3.4%). Among the 328 primary cases, males accounted for 61.9% (203 cases), with the median age (Q1, Q3) of 38.5 (27, 51) years old. Among the 1 285 secondary cases, males accounted for 59.1% (759 cases), with the median age (Q1, Q3) of 34 (17, 52) years old. The multivariate logistic regression model showed that the higher SAR was observed in the primary male cases (OR=1.632, 95%CI: 1.418-1.877), younger than 20 years old (OR=1.766, 95%CI: 1.506-2.072),≥60 years old (OR=1.869, 95%CI: 1.476-2.365), infected with the BA.2 strain branch (OR=2.906, 95%CI: 2.388-3.537), the confirmed common cases (OR=2.572, 95%CI: 2.036-3.249), and confirmed mild cases (OR=1.717, 95%CI: 1.486-1.985). Meanwhile, the higher SAR was observed in the close contacts younger than 20 years old (OR=2.604, 95%CI: 2.250-3.015),≥60 years old (OR=1.287, 95%CI: 1.052-1.573) and exposure for co-residence (OR=27.854, 95%CI: 23.470-33.057). Conclusion: The sex and age of the primary case of the Omicron variant, the branch of the infected strain, case severity of the primary case, as well as the age and contact mode of close contacts are the associated factors of SAR.

[Clinical distribution and drug resistance characteristics of carbapenem-resistant Klebsiella pneumoniae].

To explore the clinical distribution and drug resistance characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP), in order to provide reference for the prevention and treatment of CRKP infection. Retrospective analysis was performed on 510 clinical isolates of CRKP from January 2017 to December 2021, and strain identification and drug sensitivity tests were conducted by MALDI-TOF mass spectrometer and VITEK-2 Compact microbial drug sensitivity analyzer. The carbapenemase phenotype of CRKP strain was detected by carbapenemase inhibitor enhancement test. The CRKP strain was further categorized by immunochromogenic method and polymerase chain reaction (PCR) was used for gene detection. The results showed that 302 strains (59.2%) were derived from sputum, 127 strains (24.9%) from urine and 47 strains (9.2%) from blood. 231 (45.3%) were mainly distributed in intensive care, followed by 108 (21.2%) in respiratory medicine and 79 (15.5%) in neurosurgery. Drug susceptibility test result shows that the resistant rate of tigecycline increased from 1.0% in 2017 to 10.1% in 2021, the difference was statistically significant (χ2=14.444,P<0.05). The results of carbapenemase inhibitor enhancement test showed that 461 carbapenemase strains (90.4%) of 510 CRKP strains, including 450 serinase strains (88.2%), 9 metalloenzyme strains (1.8%), and 2 strains (0.4%) produced both serine and metalloenzyme. 49 strains (9.6%) did not produce enzymes. Further typing by immunochromogenic assay showed that 461 CRKP strains were KPC 450 (97.6%) and IMP 2 (0.4%). 7 NDM (1.5%); 2 strains of KPC+NDM (0.4%); PCR results were as follows: 450 strains of blaKPC (97.6%), 2 strains of blaIMP (0.4%), 7 strains of blaNDM (1.5%), and 2 strains of blaKPC+NDM (0.4%). In conclusion, CRKP strains mainly originated from sputum specimens and distributed in intensive care department, and the drug resistance characteristics were mainly KPC type in carbapenemase production. Clinical microbiology laboratory should strengthen the monitoring of CRKP strains, so as to provide reference for preventing CRKP infection and reducing the production of bacterial drug resistance.

[Construction of urban scale-free network model and its epidemiological significance in the prevention and control of COVID-19].

COVID-19 is a public health emergency currently. In this study, a scale-free network model is established based on the Spring Migration data in 2020.The cities is clustered into three different modules. The epidemic of the cities in the black module was the most serious, followed by the red and the cyan. The black module contains 9 cities in Zhejiang province and 8 cities in Guangdong province, most of them located in the southeast coastal economic belt. These cities should be the key cities for epidemic prevention and control.

[Spatial-temporal characteristics of other infectious diarrhea in Jiangsu province, 2010-2017].

Objective: To analyze the spatial-temporal characteristics of other infectious diarrhea (OID) in Jiangsu province from 2010 to 2017, and to provide evidence for setting up prevention and control programs of the disease. Methods: Data was from the Chinese Center for Disease Control and Prevention and the Statistics Bureau of Jiangsu province. Descriptive methods were used to illustrate the epidemiological characteristics of OID from 2010 to 2017. Global autocorrelation statistics method (Moran's I) was used to detect the spatial autocorrelation of OID, annually. Kulldorff M spatiotemporal scan statistics was used to analyze the spatial-temporal clustering of OID. ArcGIS 10.0 software, SaTScan 9.4 software and Excel 2017 software were also applied. Results: A total of 126 341 OID cases were found in Jiangsu province from 2010 to 2017 with an average annual incidence as 19.96/100 000. Children under five accounted for 55.08% (69 590/126 341) of the total cases. Obvious seasonal backshift with the increasing trends of the OID was noticed. There appeared four areas with high incidence of OID in the whole province, including Wuxi, Suzhou, Yancheng and Xuzhou. OID showed positive spatial autocorrelation at the county level with higher Moran's I from 0.19 to 0.33 (P<0.01). There appeared four positive clusters, all occurred in the high incidence period of OID, including the cluster area from the intersection areas of Changzhou and Wuxi (RR=7.61, LLR=2 605.80, P<0.01), respectively. Conclusion: With the increasing trends and the seasonal backshift of OID cases, pathogen surveillance programs set for those scattered children under five, in clustered regions and epidemic seasons should be strengthened.

[Interpretation for diagnosis of Yersiniosis].

Yersiniosis is one of the "other infectious diarrhea" of the notifiable infectious diseases and also an important food-borne disease. However, it lacked the basis or standard for diagnosis. The Chinese Preventive Medicine Association coordinated experienced researchers from National Institute for Communicable Disease Control and Prevention, China CDC and other institutes to produce the group standard entitled "Diagnosis of Yersiniosis" (T/CPMA 005-2019). Based on the principle of "legality, scientificity, advancement, and feasibility" , the standard gives a clear definition for Yerisiniosis, stipulates diagnosis basis, principles and main differential diagnosis and provides two informative appendixes for epidemiological and clinical characteristics and a normative appendix for laboratory detection. The standard provides accurate basis and methods of Yersiniosis diagnosis for hospitals and CDCs at all levels in China. It will solve the problems that Yersiniosis cannot be clearly diagnosed for clinical cases and in the outbreaks.

[Cost-effectiveness analysis of rabies immunization strategy based on dynamic-decision tree model].

Objective: To evaluate the cost-utility of different immunization strategies for rabies in China, and to provide a reference for determining the optimal immunization strategy. Methods: The system dynamics model was used to simulate the epidemic of canine rabies and a decision tree model was conducted to analysis different immune strategies. Relevant probabilities were obtained through literature search and on-site investigation. Sensitivity analysis was used to explore the important influenced factors. Results: At baseline, from a social perspective, 70% vaccination of dogs was the optimal strategy compared to current vaccination strategy (43% vaccination in dogs, human category-Ⅱ exposure vaccination/category-Ⅲ exposure vaccination combined with RIG). The total cost was 14 084 354 CNY, and the total utility value was 22 078 616.23 QALYs, and the incremental cost-utility ratio was-62 148 147 CNY/QALY; if human vaccination was considered, 55% vaccination of dogs combined with strategy one was the optimal strategy, its incremental cost-utility ratio was-444 620 557 CNY/QALY. The probability that an injured dog carries rabies virus was the most sensitive parameter. When it was greater than 0.005 03, strategy four was the optimal strategy. When it was less than 82/100 000, strategy one was the optimal strategy; when it was between 82/100 000 and 120/100 000, strategy two was the optimal strategy; when it was between 120/100 000 and 503/100 000, strategy two was the optimal strategy. Conclusion: It was conducive to increase the vaccination coverage of canine for the prevention and control of rabies.

[Antimicrobial resistance and molecular subtypes of Salmonella typhi and Salmonella paratyphoid isolates from Jiangsu province, 2012-2015].

Objective: To retrospectively analyze the antimicrobial resistance phenotype and molecular typing characteristics of Salmonella (S.) typhi and S. paratyphi in Jiangsu province from 2012 to 2015. Methods: The samples were collected from typhoid and paratyphoid patients in Jiangsu province. The biochemical identification and serotyping were carried out after isolation and culture. Kirby-Bauer (K-B) testing was used to detect the drug susceptibility of the strains. The molecular typing characteristics of S. typhi and S. paratyphi were analyzed by pulsed field gel electrophoresis (PFGE). Results: The resistant rates of 134 S. typhi and S. paratyphi A strains to nalidixic acid were highest (61.2% and 86.7%), while the resistant rates to remaining antibiotics were less than 15.0%. Most of S. typhi and S. paratyphi A strains were resistant to only one antibiotic. Multidrug-resistant (MDR) strains of S. typhi and S. paratyphi A accounted for 2.6% and 13.3% respectively. The composition of the all-sensitive strains of S. typhi increased by 44.3% in 2015, at the same time, there were also MDR S. paratyphi A strains, which were resistant to 5 and 6 antibiotics. S. paratyphi A could be divided into eight molecular patterns by PFGE, showing that the similarity between the MDR strains and other strains was relatively low. The S. paratyphi A strains with same pattern were resistant to same antibiotics. S. typhi could be divided into 68 molecular patterns by PFGE, with large variability between different patterns. There was no corresponding relationship between the patterns and the drug resistance characteristics. Conclusions: The overall antibiotic resistance of S. typhi and S. paratyphi A strains showed a decreasing trend, but the number of antibiotics to which they were resistant increased. PFGE patterns of S. typhi showed diversity without correspondence to antibiotic characteristics. PFGE patterns of S. paratyphi A were less with correspondence to antibiotic characteristics. We should pay more attention to key patterns in key areas.

[Prognosis and related risk factors for 465 subjects infected with hepatitis C virus in Danyang, Jiangsu province].

Objective: To investigate the clinical features and viral load of persons infected with HCV and the risk factors for severe outcomes. Methods: Medical testing and questionnaire survey were conducted on 465 cases who were infected with HCV, 20-30 years back. HCV RNA, alanine transaminase (ALT), aspartate transaminase (AST), albumin, globulin and bilirubin were tested for these subjects. Factors as demography, tobacco and alcohol consumption, SNP of rs7453920 and rs2856718 on HLA-DQ gene of subjects with HCV RNA, were analyzed by multiple logistic regression method to explore the risk factors for severe outcomes among the patients. Result: Totally, 465 subjects had symptoms as hypodynamic (15.70%, 73/465), digestive system (17.63%, 82/465), and arthrodynia (10.32%, 48/465). HCV RNA was positive in 68.60% (319/465) of the subjects with median viral load as 76.01×10(4) copies/ml (min-max: 592 copies/ml -1.08×10(10) copies/ml). Totally, 11.83% (55/465) of the cases appeared having liver inflammation by routine ultrasound exams. ALT and AST was seen higher than 80 (IU/L) in 12.70% (59/465) and 11.18% (52/465) of the subjects, separately. Factors as being male (OR =2.298, 95%CI: 1.247-4.238), GA genotype compared with AA type in rs2856718 (OR=1.716, 95%CI: 1.070-2.752), alcohol intake ≥7 times per-week (OR=2.966, 95% CI: 0.979-8.988) etc., were independently related to HCV RNA sustained positivity. Factors as: being male (OR=1.694, 95%CI: 0.975-2.942), in 50-59 years age group (OR=2.414, 95%CI: 1.156-5.042), having other liver diseases (OR=2.592, 95% CI: 1.105-6.079) and carrying positive HCV RNA (OR=3.479, 95% CI: 1.648-7.343) etc. were independent risk factors for abnormal liver function. Conclusion: High rates of carrying sustained positive HCV RNA and abnormal liver function appeared in subjects who got the HCV infection 20-30 years ago. Factors as being male, in old age, being frequent alcohol taker, GA genotype in rs2856718 and with other liver diseases etc. were related to higher risk for developing severe outcomes.