New case is a basic concept in epidemiology and often serves as the numerator for the indexes of the frequency of disease in a population． However，the exact definition of new case is still un- clear． Based on the natural history of disease combined with the concept of event-state，this article rede- fines case-related concepts and compares them with traditional concepts． The study found that the so- called new cases in traditional epidemiological studies are actually the cases firstly discovered，including newly discovered cases and identifiable newly incident cases ( disease initiation) ． In the real world，new cases are often difficult to measure，and together with the continuous process of disease development and iceberg phenomenon，those may affect the accuracy of disease frequency measurement and causal infer- ence． A correct understanding of the meaning of case-related concepts，the meanings they reflect，and the differences between them help to rationally interpret the results of epidemiological research．

Objective To analyze the regional and age-specific differences in the effects of mor- tality from respiratory diseases on life expectancy in China form 2010 to 2015． Methods We used na- tional bureau of statistics 2010 to 2015 population census，the " Chinese cause of death monitoring data set" published by China center for disease control and prevention and center for health statistics and infor- mation，national health and family planning commission． Abridged life table and arriaga method were used to explain life expectancy increment in different age groups and different regions． Ｒesults The mortality rate of respiratory diseases in China decreased from 2010 to 2015． The life expectancy after elimination of respiratory disease increased by 2. 0 years and 1. 6 years in 2010 and 2015，respectively． The contribution of the decreased mortality from respiratory diseases accounted for 15. 4 percent of life expectancy in the eastern region，12. 5 percent in the central region and 55. 6 percent in the western region． In terms of age，declines in mortality in the 0-5 and over 70 age groups contributed the most to life expectancy． Con- clusions The decline in life expectancy due to respiratory diseases was 20. 0% across the country from 2010 to 2015，showing significant regional differences． Chronic lower respiratory diseases had the greatest impact on life expectancy，but contributed less to the increment of life expectancy． Pneumonia contributed significantly to the increase in life expectancy，and the improvement of pneumonia in people aged 0-10 years promoted the increase of life expectancy．

Objective To analyze the status and trends for the prevalence，morbidity，mortality， and DALY of tuberculosis ( TB) in China from 1990 to 2017，so as to provide scientific basis for TB pre- vention and control． Methods From 1990 to 2017 in China，the United States，India，Japan，and the global，the TB ( standardized) prevalence，( standardized) morbidity，( standardized) mortality，and ( standardized) DALY rates were obtained from Institute for Health Metrics and Evaluation ( IHME) web- site，and comparative analysis of changes in these indicators with years were carried out． Ｒesults In 2017， the prevalence，morbidity，mortality，and DALY rate of TB in China were higher in the high-age group than in the low-age group． The prevalence，morbidity，mortality，and DALY rates were all higher for males than females． The prevalence was 29 641. 59/100 000 and 28 803. 26/100 000 for male and female，respectively． The male and female mortality rates were 72. 23/100 000 and 44. 85/100 000． The male and female mortali- ty rates were 3. 85/100 000 and 1. 67/100 000，and the DALY rate of male and female were 156. 95/100 000 and 84. 73/100 000． From 1990 to 2017，the prevalence of TB decreased from 32 178. 39/100 000 in 1990 to 29 231. 80/100 000 in 2017，the morbidity rate of TB decreased from 141. 83/100 000 in 1990 to 58. 83/100 000 in 2017，the mortality rate of TB decreased from 13. 82/100 000 in1990 to 2. 78/100 000 in 2017，and the DALY rate of TB decreased from 582. 87/100 000 in 1990 to 121. 60/100 000 in 2017． Conclusions The burden of TB in China declined markedly from 1990 to 2017． Although some progress has been made in the prevention and treatment of TB in China，but there is still a certain gap compared with de- veloped countries． It is still necessary to further reduce the morbidity rate and mortality rate of TB．

Objective To understand the distribution and epidemic characteristics of common pathogens of pneumonia among hospitalized children in Suzhou． Methods Nasopharyngeal secretions were collected from hospitalized children with clinical pneumonia admitted to the respiratory department of Children＇s Hospital Affiliated to Suzhou University from April 2011 to March 2018 to detect common viral and bacterial pathogens of children＇s pneumonia． Ｒesults The total positive rate of pathogens was 75. 6% in the 4 765 clinical pneumonia cases. The positive rate of bacterial pathogens was 57. 4%. Streptococcus pneumoniae ( SP) was the highest，followed by Haemophilus influenzae ( H. i) ; The positive rate of viral pathogens was 44. 1%. Ｒespiratory syncytial virus ( ＲSV) was the highest，followed by Bocavirus ( BoV) . The mixed infection rate of bacteria and virus was 25. 9%，and the most common types were ＲSV and SP，BoV and Streptococcus viride ( SV) ． Conclusions SP，H．i，ＲSV and BoV are the main pathogens of clinical pneumonia in children． There are statistical differences in different age groups and seasons of hospitalized children＇s pneumonia in Suzhou． The mixed infection rate of bacteria and virus is high．

Objective To explore the epidemiological characteristics and influencing factors of fall of elderly aged ≥ 60 years in Guangzhou from 2014 to 2018 ，so as to provide evidence for effective prevention and control measures． Methods Data on fall of the elderly was collected from the first diagno- sis in injury surveillance hospitals in Guangzhou from 2014 to 2018，and distribution description and epi- demiological analysis were adopted． Ｒesults 9 503 cases of fall of the elderly were reported in 5 injury surveillance hospitals，accounting for 49．41% of injuries in the elderly，and had occupied the first place in the cause of injury in 5 consecutive years． The sex ratio of men to women was 1 ∶ 1．67． Most of the patients had a primary or junior school degree，high rate in October-December，mainly occurred at home when doing leisure activities or life activities． The fall mainly led to injuries of head or lower extremities， contributed to contusion /bruise or fracture． And most of them were mild and moderate injury． Logistic re- gression showed that female，old age，high educational level，December to February，at home，walking， leisure activities and life activities were risk factors for falling among the elderly in Guangzhou ( all P ＜ 0．001) ． Conclusions Fall is the primary cause of injuries to the elderly in Guangzhou，especially the elderly female population． The targeted prevention and intervention measures should be developed ac- cording to their distribution characteristics．

Objective Focusing on four types acute myeloid leukemia ( AML) fusion oncogenes，so as to explore the network difference with time series expression data and further identify important genes in networks． Methods Gene network difference analysis was conducted while focusing on the global attributes of the union network． The CompNet neighborhood similarity index ( CNSI) was adopted to assess network similarity．“fast-greedy”algorithm was used to detect communities based on the union network，and further identify hub genes． Ｒesults The CNSI value between NUP98-HOXA9-3 d and NUP98-HOXA9-8 d was 0． 73，while AML1-ETO-6 h and PML-ＲAＲA-6 h was 0．25． We identified ten AML associated genes and sev- en of them ( TNF，VEGFA，EP300，EGF，CD44，PTGS2，SMAD3) were reported in the literature． Conclu- sions The network difference analysis revealed the pattern and heterogeneity of AML gene expression change across different time points，and further provided target genes for efficient treatment of AML with different types of fusion oncogenes．

Objective To analyze urine volume and dietary salt intake assessed by two 24 h urine specimens，to discuss its application value for evaluating population level and individual level dietary salt intake． Methods The subjects aged 18-69 years were selected from four counties in Shandong Province and Jiangsu Province from 2013 to 2014 by using multi-stage stratified cluster random sampling method． A questionnaire survey was conducted and two 24 h urine with an interval of one day were collected． The differences between two 24 h urine volume，and the dietary salt intake between two 24 h urine were assessed at individual level and population level． Ｒesults A total of 1 288 subjects was( 42．3± 14．0) years old，of which 626( 48．6%) were males． The average urine volume of the subjects was ( 1 462±437) ml． The first 24 h urine volume ( 1 427±488) ml was lower than the second 24 h urine volume ( 1 498± 552) ml ( t = -4．439，P＜0．001) ． The dietary salt intake was ( 9．8±3．3) g，and the dietary salt intake of males ( 10．1±3．5) g was higher than that of females ( 9．5±3．1) g ( t = 3．09，P= 0．002) ． There was a significant difference in dietary salt intake among different age groups ( F= 7．57，P＜0．001) ． The dietary saltintake of 1 136 ( 88．2%) subjects was higher than the recommended level． At the individual level，the participants with the absolute difference with 1g between the subjects’two 24 h urinary salt excretion was 279 ( 21．7%) ，and the participants with the absolute difference with ＞3 g was 48．5%． At the population level，the first 24 h urinary salt excretions ( 9．9 ± 4．1) g was similar to that in the second 24 h urine and ( 9．7±4．0) g ( P= 0．1021) ． The intraclass correlation coefficients between salt excretions in the two 24 h urine was 0．508( 95% CI: 0．451-0．559) ． Conclusion The results of this study suggest that 24 h urinary salt excretion can better assess the salt intake at population level，but cannot accurately reflect the individual’s salt intake．

Objective To analyze the treatment outcome and related influencing factors of Tibet- an nationality new smear-positive pulmonary tuberculosis patients in Qinghai Province，so as to provide evidence for tuberculosis control and treatment among Tibetan population． Methods Statistical analysis was conducted on 5 564 Tibetan nationality new smear-positive pulmonary tuberculosis cases in Qinghai province who were reported in the China Tuberculosis Information Management System and approved to receive treatment from 2008 to 2017． The main influencing factors were detected by unconditional Logistic regression model analysis，dependent variable was successful treatment or not，independent variables were other factors related to the treatment outcome． Ｒesults The treatment success rate of Tibetan nationality new smear-positive pulmonary tuberculosis cases was 87. 1% ( 4 848 /5 564) ，and the adverse outcome rate was 12. 9% ( 716 /5 564) ． Unconditional Logistic regression model analysis indicated that non-full- course supervision management，living in agricultural and pastoral area，having severe disease，floating population，and age older than 60 years were risk factors of adverse outcome． The odds ratio( OＲ) 95% confidence interval( CI) of the above risk factors were 13. 044( 10. 671-15. 944) ，2. 305( 1. 703-3. 119) ， 2. 090( 1. 346-3. 243) ，1. 967( 1. 443-2. 682) ，and 1. 909( 1. 410-2. 586) ． Clinical consultation，farmers and herdsmen were protective factors． The OＲ( 95% CI) were 0. 451( 0. 375-0. 543) ，and 0. 786( 0. 627- 0. 985) ． Conclusions Treatment success rate of Tibetan nationality new smear positive pulmonary tuberculosis cases was low． Therefore，the directly observed treatment short-course ( DOTS) strategy should be strictly implemented and the full-course supervision management should be strengthened to improve the treatment success rate． More attention should be paid to the elderly，severe，floating，agricultural and pastoral populations among the Tibetan population．

Objective To analyze the epidemic situation and characteristics of spatial autocorrelation and spatiotemporal regular of hand，foot and mouth disease( HFMD) in Yunnan Province during the period from 2014 to 2018，thus to provide theoretical basis for HFMD prevention and control． Methods Descriptive epidemiologic method was used to analyze the epidemic situation of HFMD，spatial autocorrela- tion was used to analyze the spatial cluster aggregation，and discrete Possion model in spatio－temporal in scan was used to detect HFMD＇s spatio－temporal clustering condition． Ｒesults The incidence of HFMD in Yunnan Province had been risen rapidly during the past 5 years． Cases mainly occurred among the group of male，0－4 years old group and scattered children． The predominant pathogen had changed，Other enterovir- us gradually replaced enterovirus 71( EV71) to be the predominant． HFMD cases and pathogen showed sig- nificant spatial clustering aggregation，HFMD cases hot spots mainly concentrated in the central and south－ central part of Yunnan Province． The amount of EV71 cases hot spots increased gradually，and the hot spot areas augmented and extended to the central and south－central part of Yunnan Province． There was obvious spatial－temporal aggregation of HFMD，annual scan results detected 3 first－level cluster areas and 1 second －level cluster area． Clustering time was mainly concentrated in April to October of each year． Conclusions Distribution characteristics of HFMD among people in Yunnan Province did not change significantly during the period from 2014 to 2018，while the proportion of pathogenic spectrum changed significantly． The key areas of HFMD control and prevention were still in the central and central－south part of Yunnan Province，while the aggregation and break of HFMD in these areas from April to October should be concerned．

Objective To analyze genetic characteristics of hemagglutinin( HA) gene of H9N2 avian influenza viruses( AIVs) circulating in Anhui Province from 2013 to 2018． Methods All H9N2 positive samples tested by real－time polymerase chain reaction( PCＲ) were inoculated into specific patho- gen free ( SPF) chicken eggs for isolation and purification． Viral ＲNA was reversely transcribed into cD- NA and then amplified with gene specific primers． PCＲ products were sequenced and the gene sequences were analyzed using molecular and bioinformatics software． The DATAMONKEY online server was conducted to analyze selection pressure，and protein structure homology modelling was computed by the SWISS－MODEL server． Ｒesults 33 H9N2 AIVs isolated from live poultry markets belonged to h9．4．2．5 in the phylogenetic tree． The receptor binding sites of HA gene at 183，226 and 227 position were mutated into N，L and M，respectively． Meanwhile 189 and 190 sites presented with genetic polymorphism． Since 2015，all H9N2 viruses in this study carried 6 potential N－linked glycosylation sites． It was found that po- sition 160 of HA gene was subjected greater positive selection pressure，presented 7 spatial conformations at least． Conclusions The H9N2 viruses isolated from live poultry markets in Anhui Province possess the molecular characteristics of infecting mammals and the ability of antigenic drift，so we need to pay more attention to the genetic characteristics of the viruses．