[Study on assessing early epidemiological parameters of COVID-19 epidemic in China].

Objective: To study the early dynamics of the epidemic of coronavirus disease (COVID-19) in China from 15 to 31 January, 2020, and estimate the corresponding epidemiological parameters (incubation period, generation interval and basic reproduction number) of the epidemic. Methods: By means of Weibull, Gamma and Lognormal distributions methods, we estimated the probability distribution of the incubation period and generation interval data obtained from the reported COVID-19 cases. Moreover, the AIC criterion was used to determine the optimal distribution. Considering the epidemic is ongoing, the exponential growth model was used to fit the incidence data of COVID-19 from 10 to 31 January, 2020, and exponential growth method, maximum likelihood method and SEIR model were used to estimate the basic reproduction number. Results: Early COVID-19 cases kept an increase in exponential growth manner before 26 January, 2020, then the increase trend became slower. The average incubation period was 5.01 (95%CI: 4.31-5.69) days; the average generation interval was 6.03 (95%CI: 5.20-6.91) days. The basic reproduction number was estimated to be 3.74 (95%CI: 3.63-3.87), 3.16 (95%CI: 2.90-3.43), and 3.91 (95%CI: 3.71-4.11) by three methods, respectively. Conclusions: The Gamma distribution fits both the generation interval and incubation period best, and the mean value of generation interval is 1.02 day longer than that of incubation period. The relatively high basic reproduction number indicates that the epidemic is still serious; Based on our analysis, the turning point of the epidemic would be seen on 26 January, the growth rate would be lower afterwards.

Characterization of antibody and memory T-cell response in H7N9 survivors: a cross-sectional analysis.

OBJECTIVES: Despite the importance of immunological memory for protective immunity against viral infection, whether H7N9-specific antibodies and memory T-cell responses remain detectable years after the original infection is unknown. METHODS: A cross-sectional study was conducted to investigate the immune memory responses of H7N9 patients who contracted the disease and survived during the 2013-2016 epidemics in China. Sustainability of antibodies and T-cell memory to H7N9 virus were examined. Healthy individuals receiving routine medical examinations in a physical examination centre were recruited as control. RESULTS: A total of 75 survivors were enrolled and classified into four groups based on the time elapsed from illness onset to specimen collection: 3 months (n = 14), 14 months (n = 14), 26 months (n = 28) and 36 months (n = 19). Approximately 36 months after infection, the geometric mean titres of virus-specific antibodies were significantly lower than titres in patients 3 months after infection, but 16 of 19 (84.2%) survivors in the 36-month interval had microneutralization (MN) titres ≥40. Despite the overall declining trend, the percentages of virus-specific cytokine-secreting memory CD4+ and CD8+ T cells remained higher in survivors at nearly all time-points in comparison with control individuals. Linear regression analysis showed that severe disease (mean titre ratio 2.77, 95% CI 1.17-6.49) was associated with higher haemagglutination inhibition (HI) titre and female sex for both HI (1.92, 1.02-3.57) and MN (3.33, 1.26-9.09) antibody, whereas female sex (mean percentage ratio 1.69, 95% CI 1.08-2.63), underlying medical conditions (1.94, 95% CI 1.09-3.46) and lack of antiviral therapy (2.08, 95% CI 1.04-4.17) were predictors for higher T-cell responses. CONCLUSIONS: Survivors of H7N9 virus infection produced long-term antibodies and memory T-cell responses. Our findings warrant further serological investigation in general and high-risk populations and have important implications for vaccine design and development.

[Establishment of Geographic Information System on risk assessment regarding infectious diseases imported to China].

Objectives: To establish a geographic information application system for analyzing the spatial and temporal distribution of major infectious diseases in various regions of the world and to assess the risk of importation of those diseases, to China. Methods: We collected and integrated the following information on: 1) outbreaks and areas of epidemics of major infectious diseases in the world from 2000 to 2017, 2) cases of infectious diseases in arriving travelers through active surveillance at international entry-exit ports in mainland China from 2014 to 2016, 3) numbers of annual global international flights and travelers in the country. With the above information, a global space-time distribution database on major infectious diseases was then established, using the technology related to the system. Models regarding technologies on time-space analysis, probabilistic risk assessment and geographic information visualization, were applied to establish a geographic information system on risk assessment of infectious diseases that imported to China. Results: Through integration of information on outbreaks and epidemic areas of 60 major infectious diseases in 220 countries and regions around the world, as well as 42 kinds of infectious diseases identified among the international arrivals in mainland China, a system was then developed. Information on the distribution of major infectious diseases and their potential risks in the worldwide various regions, characteristics of spectrum and disease burden of infectious diseases imported to each province of mainland China were displayed. Thus, risks on importing infectious diseases in each province via air way were able to be evaluated and simulated by the probabilistic risk assessment model, under the information on specific kind of infectious disease, outside China. Conclusion: Geographic Information System on Risk Assessment Regarding Infectious Diseases Imported to China provides basic data for epidemiological reconnaissance and assessment on risks of importing infectious diseases outside China, thus would be helpful for the improvement of strategies on surveillance, prevention and control regarding the importing infectious diseases, in China.

[Epidemiology of scrub typhus and influencing factors in Yunnan province, 2006-2013].

Objective: To understand the epidemiological characteristics of scrub typhus and influencing factors in Yunnan province, and provide further information for the prevention and control of scrub typhus. Methods: Based on the incidence data of scrub typhus reported in Yunnan from 2006 to 2013, the epidemiological characteristics of scrub typhus were analyzed and related environmental factors were identified with panel negative binomial regression model. Results: A total of 8 980 scrub typhus cases were reported during 2006-2013 in Yunnan. The average annual incidence was 2.46/100 000, with an uptrend observed. Natural focus expansion was found, affecting 71.3% of the counties in 2013. The epidemic mainly occurred in summer and autumn with the incidence peak during July-October. The annual incidence was higher in females than in males. More cases occurred in children and farmers, the proportions of cases in farmers and pre-school aged children showed an obvious increase. Panel negative binomial regression model indicated that the transmission risk of scrub typhus was positive associated with monthly temperature and monthly relative humidity. Furthermore, an "U" pattern between the risk and the increased coverage of cropland and grassland as well as an "inverted-U" pattern between the risk and increased coverage of shrub were observed. Conclusion: It is necessary to strengthen the scrub typhus surveillance in warm and moist areas as well as the areas with high coverage of cropland and grassland in Yunnan, and the health education in children and farmers who are at high risk.

[Study on the epidemiological characteristics and influencing factors of scrub typhus in the autumn-winter natural foci, from 2006 to 2013].

OBJECTIVE: To investigate the spatiotemporal expansion and risk factors of scrub typhus (ST) in Shandong, Jiangsu and Anhui provinces. METHODS: Based on the reported cases in Shandong and Jiangsu from 2006 to 2013, and Anhui from 2008 to 2013 epidemiological characteristics of ST and associated environmental factors were analyzed, using the panel negative binomial regression model. RESULTS: A total of 2 968, 2 331 and 3 447 ST cases were respectively reported in Shandong, Jiangsu and Anhui during 2006-2013, with the average annual incidence rates as 0.39, 0.38 and 0.94 per 100 000 population. Uptrend in Shandong and Jiangsu, but a slight rollback seen in Anhui were observed. Expansion of natural foci was found in the 3 provinces, with affected counties accounted for 38.0%, 48.2% and 46.5% in Shandong, Jiangsu and Anhui, respectively in 2013. Cases were clustered in autumn but with a peak of single epidemic appeared in October or November, in all the 3 provinces. More female and elderly patients were seen, than in the other age groups, in all the 3 provinces. Majority of the cases were farmers, with an increasing trend in incidence, in all these provinces, followed by housekeepers in Shandong and preschool children in Anhui. The risk factors of transmission in all the 3 provinces were negatively associated with the monthly precipitation, and showing an " inverted-U" pattern in association with monthly temperature. A positive relationship between the risk of transmission and monthly relative humidity was found in Shandong and Jiangsu provinces. However, an " inverted-U" pattern between the risk of transmission and the monthly sunshine hour, appeared in Shandong and Anhui provinces. The incidence of Scrub typhus in Shandong was also positively related to the coverage of forest. CONCLUSION: Surveillance programs and health education measures should focus on the warm and moist areas in all the 3 provinces, and also on forestry areas in Shandong. Health education and prevention on mite-bite should be targeted, especially on high-risk populations as the elderly and farmers, in the 3 provinces. Housekeepers in Shandong and children in Anhui should also be under special concern.

Gene expression signature analysis and protein-protein interaction network construction of spinal cord injury.

BACKGROUND: The aim of this study was to investigate the gene expression profile of thoracic propriospinal neurons between post-injury rat and controls. MATERIALS AND METHODS: Microarray dataset GSE20907 was downloaded from GEO database, including 12 Spinal Cord Injury (SCI) rat and 12 controls. Student's t test was employed to identified differentially expressed genes with a fold-change > 1.2. Then, we used DAVID to perform functional enrichment analysis to uncover dysfunctional biological processes and molecular signatures database (MsigDB) to find any potential relationship between SCI gene expression signature and other published gene expression signature. Protein-Protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. Functional analysis of the hub protein was performed by BinGO. RESULTS: The maximum change of gene expression profile was found at 3-days post injury and immune response was found upregulated all tested time points. Interestingly, genes upregulated 2-weeks post injury was found significantly overlapped with genes upregulated in brains from Alzheimer's disease patients. Protein interaction network analysis found that LYN, PTPN6 and SMAD1 could be of great value for further investigation. CONCLUSIONS: It could be inferred that understanding the underlying molecular mechanism post injury, especially at early moment, may provide novel insight for development of therapeutics strategy.

An approach to estimate the number of SARS cases imported by international air travel.

The worldwide spread of severe acute respiratory syndrome (SARS) raised questions about the risk of importation of such infection, in particular by air travel. Entry screening was implemented in some countries although poor evidence on its effectiveness is reported. We developed a model to estimate the number of imported SARS cases between regions, using the 2003 SARS epidemic data to apply this model for two scenarios: from Beijing to Frankfurt and from Hong Kong to London. We back-calculated the data to estimate individuals' time of infection and built a model where every individual has a probability of being isolated, of traveling, and of being undetected at arrival. The findings, consistent with what was observed in 2003, suggest that entry screening does not affect the predicted number of imported cases. Inversely, importation depends on the transmission dynamic in the country of origin (including control measures in place) and on the intensity of air travel between regions.

Granulocytic Ehrlichiae in Ixodes persulcatus ticks from an area in China where Lyme disease is endemic.

A total of 372 adult Ixodes persulcatus ticks were collected from vegetation in a forest area of Heilongjiang Province in northeastern China, where Lyme disease is known to be endemic. The ticks were examined for the presence of granulocytic ehrlichiae by heminested PCR with primers derived from the 16S rRNA gene. Of 310 ticks obtained from the Dahe forestry farm, two pools (each containing 5 ticks) were found positive, with a minimum infection rate of 0.6%. Ehrlichial DNA was also detected in one female (1.6%) of 62 ticks collected from the Yulin forestry farm. The overall minimum infection rate of the 372 I. persulcatus adults was 0.8%. The nucleotide sequences of 919-bp PCR products from the three positive tick specimens were identical to each other and very closely related to the members of the Ehrlichia phagocytophila genogroup. This is the first identification of granulocytic ehrlichiae in ticks in Asia and the first report of infection in I. persulcatus anywhere.

Identification of Ehrlichia chaffeensis by nested PCR in ticks from Southern China.

A total of 717 ticks collected from southern China were examined by nested PCR for the presence of Ehrlichia chaffeensis. Sixteen (55. 2%) of 29 adult Amblyomma testudinarium ticks and 28 (11.7%) of 240 adult and at least 4.2% of 215 nymphal (pooled specimens) Haemaphysalis yeni ticks tested positive. Four other species of ticks were negative. Selected positive amplicons were confirmed by DNA sequencing.

[Morphological and histological studies on the Chinese drug shan-dou-gen].

The Chinese drug "Shan-Dou-Gen" has been used for removing toxic heat, promoting the subsidence of swelling and soothing the sore throat since the ancient time. The authors made a survey of the drug "Shan-Dou-Gen" available in drug markets as well as the plant origin from the drug producing districts. The results showed that the drug "Shan-Dou-Gen" used in different regions in China at present are the roots or rhizomes derived from 9 species: Sophora tonkinensis Gagnep. (Leguminosae), Menispermum dauricum DC. (Menispermaceae), Indigofera amblyantha Craib (Leguminosae), I. carlesii Carib, I., fortunei Craib, I. decoa Lindl. var. ichangensis Y. Y. Fang et C. Z. Zheng, I. kirilowii Maxim. et Palibin, I. potaninii Craib, and Beesia calthaefolia (Maxim.) Ulbr. (Ranuculaceae). In this paper, the morphological characters of the crude drugs are described, compared and illustrated with photographs. The histological structures of the used parts are described, compared and illustrated with line drawings. The morphological and histological similarities and differences found among the above 9 species are summarized, and the key for the identification of the crude drugs is provided. As the drug "Shan-Dou-Gen" derived from different species has different actions and dosages, it is necessary to give different names to different species and use them correctly.