Prediction Of The Incidence Of Rubella And Analysis Of Rubella Virus Genetics,in Yinchuan

Objective:In this study,through epidemiological surveillance,the prediction for incidence rate of rubella,and the genetic study of rubella virus,we aim to understand the epidemic trend of rubella,rubella virus genotype distribution and try to trace the possible routes of transmission,so as to prevent and control the epidemic of rubella in Yinchuan City.Furthermore,providing reference data to help improve the rubella laboratory monitoring system and to promote the further development of immunization against rubella in order to bring significant social and economic benefits.Methods:1.Using statistical software to analyze and describe the three distribution characteristics of rubella in Yinchuan from 2005 to 2016;2.The exponential smoothing method and ARIMA model were used to predict the seasonal incidence of rubella in Yinchuan City in 2017;3.The molecular epidemiological characteristics of 24 rubella strains in Yinchuan from2014 to 2015 were analyzed by isolating,culturing,amplifying,purifying and sequencing of rubella virus.Results:1.The average annual incidence of rubella in Yinchuan from 2005 to 2016 was 11.75 /100000,the highest was in 2009(50.30 / 100000),and the lowest was in 2016(0.14 / 100000).The prevalence of rubella in Yinchuan was characterized by seasonal increase with single peak.The incidence peak was from March to July each year.Xingqing District was the most frequently reported area of rubella in Yinchuan,with Helan County reported at the least.Male patients in rubella cases were 1.24 fold to female patients(the difference was statistically significant).The high-incidence age group of rubella was 5 to 20 years old and mainly occurred among students and children(e.g.diaspora and kindergarten)with the transferring trend to older crowd.2.According to the characteristics of time series,the Winters’ multiplicative exponential smoothing method was used to model the incidence of rubella in Yinchuan,and the prediction of the incidence of rubella in Yinchuan in 2017 is 0.95 / 100000,0.17 / 100,000,0.04 /100,000,0.07 / 100,000;ARIMA model method(1,0,0)×(0,1,1)12 was the best one to model Yinchuan rubella monthly incidence,in 2017 the predictive value of Yinchuan rubella monthly incidence is 3cases,2 cases,3 cases,5 cases,7 cases,6 cases,2 cases,2 cases,1 case,1 case,3 cases and 1 case.3.Gene affinity analysis found that 24 cases of rubella virus isolated in Yinchuan from2014 to 2015 and WHO 2B genotypes of three reference strains together go into one branch,which independently clustered with TAN-IND-00-2B strain(Washington,USA).Yinchuan rubella formed two different cluster branches according to the year: In 2014,the cluster branch and the reference strains from Shandong,Hainan,Heilongjiang,Shanxi and Chongqing belonged to one branch.In 2015,cluster branch and the reference strains from Anhui,Tianjin,Shanghai,Hunan and Jiangsu belonged to one branch;The nucleotide homology was 98.1% ~ 100% and the amino acid homology was 97.5% ~ 100% in 24 cases of rubella virus isolated from Yinchuan.The nucleotide homology was 93.9%-100.0% with amino acid homology 95.6%-100.0% to WHO 2B genotype reference strain.The nucleotide homology between the rubella virus from Yinchuan and the national vaccine strain BDR2-CH-80-2A was 96.1% ~ 100.0%,with amino acid homology 93.4% ~ 100.0%;To compare Yinchuan rubella virus with WHO 2B genotype reference strains,although the mutation of amino acid site occurred but the key gene like E1 N-type glycosylation,neutralizing epitopes,hemagglutination inhibition and antigen epitope reminded no mutation.Compared with the vaccine strain in our country,the mutated amino acid sites were more,and the individual variation sites were located in the core functional region of the rubella virus.Conclusion:1.In recent years,the annual incidence of rubella in Yinchuan has been declining down and is controlled at a low level,mainly occurred in distribution or aggregation.We should focus on rubella in the early spring and early summer,especially among primary and junior school students or women of child-bearing age.Besides,high population density or economic condition at relatively low areas should be under the monitoring,prevention and control.2.For the time series,exponential smoothing method and ARIMA model both are qualified predictors to the seasonal incidence of rubella in Yinchuan,but the prediction model is not static.After the time series is updated and supplemented,the prediction model needs to be amended and updated accordingly.3.24 cases of Yinchuan rubella virus strains are 2B genotype and independently clustered with the reference strain from Washington DC;Yinchuan rubella may be spread from Guangdong Zhanjiang through multiple transmission chain;The core sequence of E1 gene isolated from Yinchuan rubella virus did not mutate,remaining highly conserved state;The RV-Vaccine could provide good-efficiency immune protection for Yinchuan rubella virus.