| Measles is a common acute childhood respiratory infectious disease caused by measles virus(MV),which is mainly transmitted by respiratory droplets,direct and indirect contact.MV has a single serotype,so it is theoretically feasible to eliminate measles by vaccination.Vaccination campaigns have achieved remarkable results in reducing morbidity and mortality in children,but in recent yearly,some countries have seen an increase in the incidence.Therefore,measles remains an important public health problem worldwide.The incidence of measles in Shandong Province is basically consistent with that in the whole country.The disease burden of measles in Shandong Province was relatively heavy and the incidence rate was high before 2017,and the situation improved in recent years.However,MV is highly contagious and easily spread among regions.Therefore,relevant departments should not relax their vigilance against measles prevention.Measles has a high incidence in winter and spring every year,suggesting that the spread of the disease may be affected by meteorological factors.MV is highly contagious,and outbreaks are very likely to occur in densely populated places,suggesting that the spread of the disease may be related to human contact.Although measles can be prevented by vaccines,under the premise that the national vaccination rate of measles is high,the incidence still has the characteristics of uneven distribution in various cities,suggesting that it may be related to economic,medical,and et al.Therefore,it is of great significance to explore the influence of meteorological factors,demographic and socioeconomic factors on measles.A review of a large number of literatures found that the incidence of measles has obvious spatial autocorrelation,spatiotemporal aggregation and spatial trend,but the current researches on relationship between influencing factors and measles seldom consider the impact of spatiotemporal effects.With the development of spatiotemporal statistical analysis methods,spatiotemporal Bayesian model has been widely used in the field of infectious diseases.Compared with traditional modeling methods,this model uses priori information and integrated nested Laplace approximations(INLA)to estimate the posteriori margins of effects,and comprehensively considers independent and identically distributed(iid)spatiotemporal random effects,spatial intrinsic conditional autoregressive(iCAR)and nonparametric temporal trends,which can not only be used to estimate the regional risk of disease,but also adjust the effects of influencing factors.So the influencing factors and spatiotemporal effects of measles can be well estimated.This study based on measles data,using spatiotemporal Bayesian model to estimate the impact of meteorological,demographic and socioeconomic factors on the measles in Shandong Province at the county scale.It aimed to provide theoretical evidence for formulate of accurate and efficient public health measures for measles elimination,and also to provide reference ideas for the other infectious diseases research.Materials and MethodsThe surveillance data of measles cases in 136 counties(districts)of Shandong Province from 2009 to 2017 were collected,and the three distribution characteristics of measles were epidemiologically described.The data on monthly meteorological factors,annual demographic and socioeconomic factors data in the same period were collected for the next step.The covariables were sorted into categorical variables and divided into four levels from Q1 to Q4.Considering the spatiotemporal random effects of measles,zero inflation and over dispersion of data,using the zero-inflated negative binomial spatiotemporal Bayesian model estimated the effects of meteorological,and demographic and socioeconomic factors on measles,and to evaluate the measles risk areas at county(district)level.At the same time,the case population was divided into multiple subgroups according to different genders,ages and occupations,and differences in the effect of influencing factors in the subgroups analysis was compared.Results1.During the study period,15673 measles cases were reported in Shandong Province.The male-female ratio of cases was 1.32:1.The cases age groups were mainly<5 years old(49%)and 20～39 years old(32%),among which male cases were predominant in children<5 years old,and female cases were mainly in adults aged 20～39 years,and it was more common among diaspora children(48%)and farmers(25%).The incidence of measles fluctuated greatly year by year with a high incidence from February to May,with obvious single peak seasonal characteristics.The incidence of measles in the western part of Shandong was significantly higher than that in the eastern part,but the incidence of measles in individual counties(districts)along the east coast was higher.2.The risk of measles was lower when the temperature or relative humidity were higher.The risk of measles was higher when the wind speed,the sunshine hours or the diurnal temperature variation were higher.The effects of precipitation on the measles showed a "V"shape.Taking the lowest level of the variable(Q1)as a reference,the RRs(95%CI)for higher temperatures(Q2～Q4)were 0.79(0.69～0.91),0.54(0.44～0.65),and 0.48(0.38～0.61),respectively;the RRs(95%CI)for higher relative humidity(Q2～Q4)were 0.76(0.66～0.88),0.56(0.47～0.67),and 0.49(0.38～0.63),respectively;the RRs(95%CI)for higher wind velocity(Q2～Q4)were 1.43(1.25～1.64),1.85(1.57～2.18),2.00(1.59～2.52),respectively.Subgroup analysis found that adults aged 20～39 and farmers subgroups were more vulnerable to meteorological factors such as sunshine duration and wind velocity.3.The counties with high population density and high urbanization rate had a high risk of measles.When the per capita net income of rural was at mid-low level(Q2),the risk of measles was reduced.Taking the lowest level of the variable(Q1)as a reference,the RRs(95%CI)for higher population density(Q2～Q4)were 1.29(0.99～1.67),1.61(1.21～2.13),1.63(1.20～2.21),respectively;the RRs(95%CI)for higher urbanization rate(Q2～Q4)were 1.30(0.93～1.80),1.28(0.87～1.90),1.62(1.05～2.51),respectively;the RRs(95%CI)for higher per capita net income of rural(Q2～Q4)were 0.73(0.56～0.96),1.06(0.76～1.43),1.12(0.80～1.57),respectively.4.The medium-high-risk counties(districts)of measles were mainly concentrated in Jinan City,followed by Heze,Zaozhuang,Liaocheng,Binzhou,Jining,Linyi,Qingdao,Dezhou City,and other cities had no medium-high-risk counties,which was basically the same as the regional distribution of measles incidence.Conclusions1.The male-female ratio of measles cases in Shandong Province was 1.32:1.The main cases were people aged<5 years,20～39 years,scattered children and farmers.The incidence of measles showed single peak seasonal fluctuation.The incidence in the west was higher than that in the east of Shandong Province.2.Temperature,relative humidity,wind velocity,and sunshine duration were the main factors affecting the measles.Compared with other subgroups,the risk of measles in adults aged 20～39 years and farmers subgroups was more affected by meteorological factors such as sunshine duration and wind velocity.3.In counties with high population density and high urbanization rate,the risk of measles was high;when the per capita net income of rural was at mid-low level(Q2),the risk of measles was reduced.4.The medium-high-risk counties of measles in Shandong Province were mainly concentrated in some counties in the northwestern,southern of Shandong and central Shandong. |
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