| Objectives:Following the global eradication of polio, the World Health Organization(WHO) has eliminated measles as the next target. With the unremitting efforts of all countries, the incidence of measles showed a significant decline but has not been eliminated. Measles elimination in China wasn’t going smoothly as well. The incidence in 2012 dropped tohistoric lows, but has been reboundedin 2013, besides that in 2014, there has been ameasles epidemic in different provinces, and therefore it is very necessary to study the epidemiology of measles outbreaks.In the background of high vaccine coverage, measles outbreaks in Jilin province are stilluncertain, we analyzed theepidemiological characteristics and clinical manifestation reported cases of measles in Jilin province from 2009 to 2014. Discuss the main reasons and factors of high measles incidence in Jilin province. Find high-risk populations and high-risk areas toprovide prevention counter measures and suggestions to reduce the incidence of measles. Methods:The data information of 2009-2014 Jilin province measles cases is collected from Measles Surveillance System(MSS) all reported cases. We described the epidemiological characteristics of measles outbreaks in Jilin province,all measles cases were divided into five groups according to age:<8 months old, 8-23 months, 2-6years old, 7-14 years and ≥15 years old, systematic random sampling200 cases from each group, from non-measles cases we randomly selected 200 in each age groupas controls, and analysised the factors associated with measles outbreaks,we collected laboratory confirmed measles cases, and analyzed the influence of different component of Measles-containing Vaccine(MCV) immune history on the clinical symptoms of measles.Using Excel2007 sorts through case data and Map Info software described the geographical distribution of measles incidence in different years. Using SPSS17.0 for statistical analysis, single factor Logistic analysis, inspection level is 0.05; multiple factors logistic analysis, using the enter method, inclusion criteria is 0.05, exclusion criteria is 0.1,qualitative data application test, non-parametric data usagerank sum test, inspection level of 0.05. Results:Epidemiological characteristics of measles: 6156 cases of measleswere reported in Jilin province from 2009 to 2014, the annual incidence rates were 8.79/100000, 1.15/100000, 0.08/100000, 0.08/100000, 0.61/100000 and12.96/100000 respectively, the average annual incidence was 3.95/100000, the male to female ratio was1.30:1;50% of the cases in Jilin province occurred each year from April to June, a high incidence of measles concentrated in the northwest, meanwhile other areas showed varying degrees of distributing; measles cases were mostly scattered children(3383 cases), followed by peasants(868 cases), mainly distributed in the age compositionof <8 months(26.1%), 8-23 months(26.0%) and over15 years old grown-ups(36.5%). 2014 measles outbreaks are approximately the same time compared with 2009, while the proportion of scattered children decreases, and the constituent ratio of house keeping service practitioners,unemployed people and workers increases, aslo the male proportion decreases; according to Jilin province statistical yearbook 2014 demographic data we analyzed the relations between gender and measles, it is shown that measles risk of maleis 1.267 times that of female(P<0.05, 95% CI: 1.205-1.332).Case-control study findings: excluding the influence of age and gender, in8-23 months old groupsthe measles risk of the population with MCV≥1 immune history is0.533 times than that of MCV=0 population,(P<0.05,95%CI: 0.353-0.806), the measles risk of immune history unknown population is 3.267 times than MCV=0 population(P<0.05,95% CI: 1.058-10.089); in2-6 years old groups, comparing with 0 in oculation of MCV, MCV≥1 population measles risk OR value is 0.622(P< 0.05, 95% CI: 0.392-0.986), the MCV immune history unknown population measles risk OR is 4.381(P< 0.05, 95% CI: 1.686-11.387); in 7-14 years old groups, comparing with MCV 0 in oculation, MCV≥1measles risk OR is 0.456(P<0.05, 95%CI: 0.240-0.869), the MCV immune history unknown population measles risk OR=0.258(P<0.05, 95% CI: 0.126-0.530); in ≥15 years old groups, comparing with MCV 0 in oculation,MCV≥1population measles risk OR is 0.376(P<0.05, 95%CI: 0.166-0.849), the MCV immune history unknown population measles risk OR=0.812(P < 0.05, 95% CI: 0.535-1.234). There is no significant difference of other influence factors between age groups(P>0.05).Clinical symptom analysis:among all laboratory confirmed cases, 99.3%showed fever,99.6%developed rash,95.2% had coughing, 79.1% were reported with catarrh symptoms, 77.4% and 57.4% were found with conjunctivitis and oral mucosa spot. The multi-factor Logistic regression analysis showed that the immune history MCV ≥ 1 measles cases versus MCV=0 cases,OR value of coughing was 0.514(P<0.05,95%CI: 0.369-0.714), oral mucosa was 0.451(P<0.05,95%CI: 0.386-0.529). ConclusionsMeasles outbreaks in Jilin province show seasonal and regional concentrating characteristics, mainly onset time is April to June each year, most cases concentrated in the northwest of Jilin province, infected population sare mostly scattered children and showing "bimodal distribution" from low age groups to adults, malesare more susceptible to measles than females; previous immunization strategy plays a protective role aganist measles, also strengthens the coverage of measles vaccines.Related factors analys is demonstrated that immune history MCV≥1 may be a protective factor for measles.Clinical characteristics of measles have changed under the vaccine interventions, measles cases with immune history MCV≥1 have milder symptoms of coughing and oral mucosa spot than the ones with 0 MCV inoculated history,therefore it is important tovaccinate MCV to reduce the risk and alleviate clinical symptoms. Summarizing the epidemiological characteristics findings above, to combine with the prevention and control measures for Jilin province high-risk areas and susceptible populations reported in 2015 Jilin province measles risk assessments, we shall make every effort to eliminate measles. |
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