| Objective To analyze the epidemiological characteristics,spatial aggregations and risk factors for human infections with avian influenza H7N9 in Fujian Province,and provide scientific evidence for developing and adjusting related control strategies.Methods Descriptive statistics was used to describe the epidemiological characteristics of human infections with avian influenza H7N9 in Fujian province.Spatial analysis was performed to examine the spatial aggregation characteristics.Multi-factor logistic regression was conducted to identify the potential risk and protective factors for human infections with H7N9 avian influenza in a case-control study.Results1.There were a total of 108 cases and 28 deaths reported and confirmed as human infections with H7N9 avian influenza in Fujian Province from April,2013 to December,2018.The case fatality rate was 25.93%.2.96.30%of human infections with avian influenza H7N9 in Fujian were sporadic.Patient age ranged from 1.75 to 88 years old,with a median age of 55.50.There were more incidences in winters and springs(?~2=192.67,P<0.01),more incidences in rural areas than urban areas(?~2=7.41,P=0.01),more male patients than female patients(male 76.85%,female 23.15%,?~2=8.04,P=0.04).The most frequent patient occupations were peasants(30.56%),household workers and workers waiting for employment(25.00%),and retired workers(9.26%).92.59%of reported cases had exposure history to poultry,of which 63.89%were exposed in live-poultry markets.71.43%of the exposure sites tested positive.15.12%to 30.71%of poultry and environmental samples tested positive,and the positive rates were increasing by the year(Z=2.98,P<0.01).The median durations from onset to treatment,hospitalization,diagnosis and antiviral therapy were 3 days,5 days,7 days,and 6 days,respectively.The median duration from disease onset to death were 16 days.46.3%of the cases also had chronic diseases.The increase of age was associated with elevated chronic disease prevalence(Z=4.75,P<0.01)and the incidence of critically ill cases(Z=5.07,P<0.01).No significant differences were found in case fatality rates between male and female(?~2=1.67,P=0.20),nor among the age groups(?~2=2.23,P=0.53).However,case fatality was related to cardiovascular disease(OR=2.60,95%CI:1.06-6.39),pneumonia(OR=1.27,95%CI:1.13-1.42),critically ill(OR=1.24,95%CI:1.13-1.42),requiring ICU(OR=3.80,95%CI:1.20-11.99),multiple bacteria infections with antibiotic treatment(OR=1.19,95%CI:1.08-1.32)and requiring hormonal treatment(OR=7.47,95%CI:1.64-33.95).3.Results from global spatial autocorrelation and high/low clustering analysis indicated that case aggregation at the county level was in the shore areas(Z=3.74,P<0.01;Z=5.26,P<0.01).Changle,Fuqing,Jinjiang and Siming were the four high-high aggregation areas and local hot-points.Two spatial aggregation areas were identified,both occurred during December 2014 to March 2015.The most probable spatial aggregation identified was an area with 63.04 Km radius and centering Zhangpu county(RR=4.72,LLR=11.41,P<0.01).The second probable spatial aggregation identified was an area with 81.98 Km radius and centering Fuqing city(RR=4.07,LLR=7.96,P=0.03).4.Risk factor analysis of the case-control study showed that the two contrast groups had no significant differences in terms of gender,age,residency(urban or rural)and BMI index.Univariate analysis suggested 36 factors associated with avian influenza infection,including having chronic diseases,exposure to live poultry market,exposure to domestic poultry,exposure to wild fowl,exposure to poultry workers,personal hygiene and behavioral habits.Further analysis using multi-factor stepwise logistic regression had found risk factors for the infection with avian influenza H7N9:pulmonarydisease(OR=4.95,95%CI:1.36-18.00),diabetes(OR=4.46,95%CI:1.64-12.09),exposuretolivepoultrymarket(OR=3.66,95%CI:1.58-7.66),exposuretopoultryepilationsites(OR=5.78,95%CI:1.84-18.13),contact with poultry cage(OR=5.77,95%CI:2.20-15.12),exposure to wildfowl feces.Regular hand-washing(OR=0.07,95%CI:0.04-0.16),may reduce the risk of disease.The regression equation had 89.40%prediction accuracy on training samples and fair goodness of fit statistics.Conclusion Human infections with avian influenza A(H7N9)virus in Fujian Province had more occurance in winter and spring,in rural areas,in coastal areas,in male and in the elderly.Cases that were critically ill increased with age.Pulmonary disease,diabetes,exposure to live poultry market,exposure to poultry epilation sites,contact with poultry cage and exposure to wildfowl feces were the risk factors for human infections with avian influenza H7N9.Regular hand-washing was a protective factor. |
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