Epidemiological Characteristics Of Human Infection With H7N9 Avian Influenza And Risk Factors Of Death

Objective The epidemiology of human infection with H7N9 avian influenza in Anhui Province from 2013 to 2017 was described,and its characteristics were comprehensively analyzed.To compare and analyze the epidemiological characteristics of human infection with H7N9 avian influenza cases in different epidemic seasons in Anhui Province from 2013 to 2017,and explore the differences in epidemiological characteristics and clinical characteristics between dead cases and surviving cases on the basis of analysis of the epidemiological characteristics of related cases.To explore the risk factors of death and provide a relatively scientific theoretical basis for future clinical treatment.Methods 1.Analysis on the epidemiological characteristics of 102 cases of human infection with H7N9 avian influenza in Anhui Province from 2013 to 2017 Data were entered using Excel 2016 software,the database was established using Epi Data3.1 software,and statistical analysis was performed using SPSS 23.0 software.Means consistent with normal distribution were compared using the t-test.For non-normal distribution data,the non-parametric test Mann-Whitney U test was used to compare the median,and the median and interquartile range(IQR)were also taken.For the comparison of enumeration data or classification data,2 test is mainly used,with test level?=0.05.Location distribution of cases was mapped using Arc GIS 10.2 software.2. Analysis of risk factors for death of 99 cases of human infection with H7N9 avian influenza in Anhui Province from 2013 to 2017 From March 30,2013 to August 31,2017,99 confirmed cases of human infection with H7N9 avian influenza reported by medical and health institutions at all levels in Anhui Province were used as the study subjects(excluding 3 cases with severely missing data).Epidata 3.1 software was used to establish a database,Excel 2016 software was used to collate the data,SPSS23.0 software was used for statistical analysis and receiver operating characteristic(ROC)curve was plotted.Means consistent with normal distribution were compared using the t-test,and means with non-normal distribution were compared using the non-parametric test Mann-Whitney U test,and medians and interquartile range(IQR)were taken.The?~2 test was mainly used for the comparison of enumeration data or categorical data,and the odds ratio(OR)value and 95%confidence interval(CI)were calculated.Test level?=0.05.Results:1.Epidemiological characteristics of human infection with H7N9 avian influenza Since the first wave of epidemic situation in Anhui Province in 2013,the fifth wave of epidemic situation occurred as of August 31,2017.102 cases of human infection with H7N9 avian influenza in 5 waves of epidemic situation were reported through the China Information System for Disease Prevention and Control,with a cumulative number of 51 deaths.Distribution of case onset time:The high incidence month was February?May each year,but the incidence of the fifth wave of epidemic was earlier than that of the first four waves of epidemic,and the number of cases increased but the mortality rate decreased.Distribution of age of onset of cases:The age information of 102 confirmed cases was reported from 2013 to 2017.The age ranged from 3 to 91 years,and 58 years.There was significant difference in the possibility of death of confirmed cases between age groups,with age and mortality.Gender distribution of cases:102 confirmed cases:27 females and 75 males.There was no statistically significant difference in gender composition among human infection with H7N9 cases diagnosed within the five epidemic seasons(?~2=9.14,P=0.06);occupational distribution of case incidence:of the 102 confirmed cases,25 were farmers and 23 were retirees;distribution of case incidence areas:during the five epidemic seasons from 2013 to 2017 in Anhui Province,102 human infection with H7N9 avian influenza cases were diagnosed cumulatively,of which 64 cases were from urban areas and 38 cases were from rural areas.There was no significant difference in the residence(rural or urban)of confirmed cases in different epidemic seasons(?~2=2.02,P=0.73);case exposure history:of 102 cases,61 cases had a history of contact with live poultry,accounting for 59.8%,of which 24 cases were exposed to domestic/free-range live poultry,accounting for 39.34%,5 cases were exposed to live poultry in farms,accounting for 7.84%,45.90%were exposed to live poultry in farmers'markets,and 4cases were exposed in other forms,accounting for 6.60%;case history of underlying diseases:the prevalence of underlying diseases in males was 60.0%(45/75),the prevalence of underlying diseases in females was 48.1%(13/27),and there was no difference in the prevalence of underlying diseases between genders(?~2=1.14,P=0.29);Complications occurred during treatment in 83 cases.Sixty-six patients were male and22 were female;4 patients had complications from 0 to 14,17 patients had complications from 15 to 44,24 patients had complications from 45 to 59,22 patients had complications from 60 to 69,and 16 patients were over 70 years of age;disease duration:the median time from onset to first admission,onset to diagnosis,time interval from admission to diagnosis,time interval from onset to first use of oseltamivir,time interval from use of oseltamivir to death or cure,and time interval from onset to first use of Tamiflu were 4 days,7 days,3 days,6 days,14 days,and 6 days,respectively,and the time interval from admission to diagnosis of confirmed cases was significantly different in five different epidemic seasons(Z=9.97,P=0.04).2. Analysis of risk factors of death in human infection with H7N9 avian influenza Deaths occurred mainly with the emergence of the H7N9 avian influenza epidemic,38males,accounting for 76.00%of the total deaths,and 12 females,accounting for24.00%of the total deaths.Most of the deaths were older,with an average age of 64years,the youngest was 28 years old,and the oldest was 91 years old.Deaths aged 60years and above accounted for 68.00%(34/50)of the total deaths.There was a significant difference in the age of cases between the two groups(t=5.12,P<0.01);the occupational distribution of deaths caused by human infection with H7N9 avian influenza was mainly retirees and farmers,accounting for 60.00%of the total deaths,of which the mortality rate of retirees was significantly higher than that of the cured group,and the difference was statistically significant(?~2=8.11,P<0.01);60 cases had a history of live poultry exposure,accounting for 60.61%of the total cases;63 cases had a history of farmers'market exposure,accounting for 69.70%of the total confirmed cases.The history of farmers'market exposure before the onset of the disease in the death group was higher than that in the cured group,but there was no significant difference between the two groups(?~2=0.89,P=0.35);54.90%of the deaths had a history of hypertension,significantly higher than 21.57%in the cured group,and there was significant difference between the two groups(?~2=13.26,P<0.01);there was significant difference in the occurrence of complications,such as ARDS,septic shock and MODS,between the cured group and the dead group;the median duration of the disease was 23days in the cured group and 17 days in the dead group,and there was significant difference between the two groups(Z=-2.82,P<0.01);the median latency period was 3days in the cured group,1 day in the longest was 17 days,and there was significant difference in the length of latency period between the cured group and the dead group(Z=-2.05,P=0.04);There were 8 cases who used antiviral drugs within 48 hours after the onset of cure,accounting for 16.33%of the total number of cases in the cured group.There was no significant difference between the two groups,but the proportion of drugs used within 72 hours in the cured group was significantly higher than that in the death group,and the difference was statistically significant(?~2=4.55,P=0.03);patients aged?60 years(OR=5.28,95%CI:2.23-12.48),hypertension(OR=4.18,95%CI:1.62–10.78),ARDS(OR=7.98,95%CI:2.78–22.95),septic shock(OR=17.38,95%CI:2.01–150.00),MODS(OR=23.68,95%CI:2.92–191.92)and incubation period>3 days(OR=6.22,95%CI:1.57–24.59)could increase the risk of death in H7N9 avian influenza cases;ROC curve analysis results showed that age(AUC=0.77,95%CI:0.67–0.86,P<0.01),incubation period(AUC=0.65,95%CI:0.51–0.79,P=0.04)and disease duration(AUC=0.66,95%CI:0.56–0.77,P<0.01)of confirmed cases of human infection with H7N9 avian influenza had some predictive value for the prediction of clinical death outcomes.Conclusion:The occurrence of the epidemic situation of human infection with H7N9avian influenza in Anhui Province showed a significant seasonal high incidence,with more incidence in winter and spring and fewer cases in summer and autumn.There was no obvious time and regional clustering characteristics of human infection with H7N9avian influenza cases in Anhui Province,which mainly occurred with the emergence of H7N9 avian influenza cases.There were many elderly cases infected with H7N9 avian influenza virus;the mortality rate of retirees in the death group of human infection with H7N9 cases in Anhui Province was higher than that in the cured group,and most deaths would have complications,mainly severe pneumonia and ARDS,and the occurrence of ARDS,septic shock and MODS complications may be risk factors for the death of human infection with H7N9 avian influenza cases.Neither history of live poultry exposure nor history of farmers'market exposure was associated with the outcome of the disease.