| Mumps is an acute respiratory infection caused by mumps virus invading the parotid glands and a high prevalence in children and adolescents who are most susceptible to it.It can be prevented through vaccines.With the use of mumps vaccines,the incidence of mumps has decreased significantly in many countries.However,in recent years,some countries reported mumps outbreaks.Since 2008,China has integrated the measles,mumps and rubella vaccine into the national immunization program,which has controlled the occurrence of mumps to a certain extent.However,the incidence of mumps is still high,with hundreds of thousands of mumps cases reported every year.As a province with a large population and population movement,the cases of mumps in Shandong Province in 2012 and 2013 were as high as 25/100000,suggesting that mumps is still an important public health problem in Shandong Province.Climate change has become a serious threat to human health.Most current studies have also shown that meteorological factors are related to the incidence of mumps,but most of these studies are based on the use of different analysis methods or different models in a single city or region to explore the effects of meteorological factors on mumps.Provincial-level studies are very limited.Therefore,the purpose of this study was to describe the epidemiological characteristics of mumps in the province and its cities during the study period based on time series data,to explore the relationship between meteorological factors and mumps in 17 cities in Shandong Province,and to obtain a province-levels average impact of meteorological on mumps and explore its heterogeneity,provide a basis for mumps prevention and control,help relevant departments to take targeted measures,adapt to local conditions,and reduce the risk of mumps.Methods:Daily reported mumps cases and meteorological factors from January 1,2009 to December 31,2017 in various cities in Shandong Province were collected.Describe the epidemiological characteristics of mumps in the province and its cities during the study period.Adopted two-stage analysis method.In first stage,by modeling distributed lag nonlinear model,the effects of daily mean temperature and daily mean relative humidity on mumps were studied under the control of long-term trend,seasonal trend,day of the week and other meteorological factors.In the second stage,the effects of temperature and relative humidity on mumps in different cities were pooled by multivariate meta-analysis to obtain the average effect value at the Shandong provincial level.The effects of temperature and relative humidity on mumps were stratified.Meta regression was used to explore the influence of the covariates included in this study on the merger effect in meta-analysis in an attempt to identify the source of heterogeneity.Results:1.From 2009 to 2017,a total of 104,685 cases were reported in Shandong province,with an average annual incidence of 11.94/100,000.The top three cities were Dongying,Zaozhuang and Jining,while Yantai and Weifang had relatively low incidence.Daily mumps cases in Shandong Province showed a certain periodicity and seasonality,indicated a slight decline(2009-2010),then an accelerated rise(2010-2012),and then continue to decline(2012-2017).The incidence of mumps in various cities was similar to the whole province.There were two peaks each year in the province and its cities,a large peak was from April to July,and a small peak was from December to January.The incidence of male was higher than female in all cities and the high incidence of mumps was mainly in the age of 0-20 years,and the age of 5-15 years old was highest.The high incidence population was students,nursery children and scattered children.During the study period,mumps occurred in almost all counties in Shandong Province,but the main occurrence areas were different in different years.The overall trend showed a high incidence in the west,a low incidence in the east,a high inland and a low coastal.2.There was a large overlap between the daily mean temperature and the daily mean relative humidity range in each city.According to the median daily mean temperature of 14.7? in Shandong Province,the exposure response curves between temperature and mumps in each city were non-linear and vary from city to city,but most of the curves were "V","L" and "S" type.Taking the median daily relative humidity of 67%as a reference,it showed that the exposure response relationship between relative humidity and mumps in different cities was non-linear,and the effects of different cities were different,most of the curves showed a "V"and "S"type.3.At the level of Shandong province,the exposure-response curve between temperature and mumps was approximately "L".With the reference of 14.7?,the pooled cumulative relative risk of mumps was the highest at-12.6?,RR=2.429(95%CI:1.339-4.407),and the lowest at 29.7?,RR=0.759(95%CI:0.545-1.056).The cold effect of temperature on mumps presented a dangerous effect at different lag time,and the risk was the highest at lag 1day,RR=1.035(95%CI:1.002-1.069),and the risk was the lowest at lag 14 days,RR=1.022(95%CI:1.008-1.036).The thermal effect of temperature on mumps presented a protective effect at different lag time,but had no statistical significance.The exposure response curve between relative humidity and mumps was similar to "S" type,with 67%as the reference.The relative risk was the highest when relative humidity was 99%,RR=1.255(95%CI:0.975-1.615),and the lowest when relative humidity was 16.5%,RR=0.767(95%CI:0.463-1.272),but there was no statistical significance.The effect of low relative humidity on mumps was not statistically significant at every lag time,but at high relative humidity,the effect appeared at 13 day's lags,with the highest risk at 15 days,RR=1.015(95%CI:1.002-1.028).4.There was heterogeneity in the pooled effect of temperature on mumps(Q=95.447,P=0.000),and the heterogeneity size I2=49.7%.The Wald test results showed that the heterogeneity came from the proportion of primary and secondary school students(Stat=8.374,P=0.039).There was heterogeneity in the pooled effect of relative humidity on mumps(Q=75.505,P=0.007),and the heterogeneity was I2=36.4%.However,there was no statistical significance in Wald test when covariates such as longitude were included in this model.Conclusion:1.During the study period,the incidence of mumps in Shandong province and various cities showed seasonality.The cities with higher incidence rates were Dongying city,Zaozhuang city ang Jining city,and Yantai city,Weifang city were relatively low.The high incidence age group was 5-15 years old and main population was students,nursery children and scattered children.Mumps occur in almost all counties,and the main areas were different in different years.The overall trend was approximately high in the western and inland regions,and low in the eastern and coastal regions.It was suggested that relevant departments should focus on high-risk populations and areas to do the early warning and prevention of mumps.2.The effect of daily mean temperature on mumps in Shandong province was that the risk was high at low temperature and was low at high temperature,and the effect of low temperature was delayed.The effect of daily relative humidity on mumps showed that under the threshold,the relative risk increases gradually with the increased of daily relative humidity,and then decreased and then increased gradually.The exposure-response curve of daily average temperature and relative humidity to mumps varies in different cities.Most cities were similar to provincial levels.It was suggested that relevant departments should strengthen the prevention and control of mumps when the temperature was relatively low and/or the relative humidity was low to reduce the risk of mumps.3.There was heterogeneity in the pooled effect of daily mean temperature and relative humidity on mumps.A high proportion of elementary and middle school students can increase the risk of mumps at low temperatures.The results suggested that protection of population of primary and middle school students should be strengthened at low temperatures,increase public awareness,and the supply of health resources. |
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