The Study Of Measles Epidemic Factors In Quanzhou

ObjectThrough the analysis of the characteristics of measles epidemic in Quanzhou and its morbidity factors, to provide a basis for measles prevention and control measures.MethodAnalyzing characteristics of measles epidemic situation in Quanzhou via descriptive epidemiology ; for analyzing measles morbidity factors, using 1:2 case-control study; by way of multi-stage random, sampling bloods taken from children under the age of 15 years old and neonatal umbilical cord blood from obstetric hospitals at city-levels and township-levels for measles IgG antibody level tests; applying micro-cell culture to isolate wild strains of measles virus in Quanzhou, and using RT-PCR and molecular biology methods such as gene sequencing to conduct genotyping and mutation analysis of popular wild strains of measles virus, using neutralization test to analyze antigenic drift of wild measles virus; through the emergency vaccination of the target population evaluating effectiveness of vaccine inoculation.Results1.Through 2006 to 2008, the areas in Quanzhou where measles incidences were relatively higher were Jinjiang City, Shishi City, Licheng District, Fengze District, and Nanan City, representing 86.82% of the total number of cases in Quanzhou; annually, the incidence peak occured in the May-to-August period; among the cases,children under the age of 15 accounted for 77.75%, the percentage of less-than-8-month-old cases increased from 5.81% in 2004 to 15.67% in 2008 , the cases of floating population accounted for 57.01% of the total; the cases with the measles vaccine immunization history accounted for only 10.76 %.2. Measles vaccine(MV) immunization was a protective factor, with MV protective effect being 91.5% ~ 99.9%; visting hospitals and contacts with rash patients 1～3 weeks prior to illness onset were risk factors;the risk of morbidity arised with the increase of exposures to hospitals;The risk increased gradually with exposures to the village-level health care units, the-county-level medical units and Quanzhou Children's Hospital respectively, the riskiest being to the highest City Children's Hospital,OR = 54.160 (95% CI = 7.219～406.317).3. The positive rate and protection rate of measles antibody among healthy resident children in Quanzhou were 82.50% and 62.21% respectively, with antibody geometric mean titer (GMT) at 1:1804.68. Measles antibody levels were closely related to the incidence of measles.There were differences in antibody positive rates and GMTs in different areas of Quanzhou , with the lowest in Fengzhe and the highest in Huian. GMT levles in rural areas were higher than in urban areas. Antibody positive rates and GMTs increased with the increase of measles vaccination needle times.4.In 2008 we examined measles antibody of umbilical cord blood of normal-childbirth newborn babies, antibody-positive rate being 96.97% in accordance with the postive criteria of 1:200 and above ,or 90.40% in accordance with the postive criteria of 1:800 and above, average geometric mean antibody titer being 1:3020.65. The GMT level of the measles incidence group was much higher than the vaccination group and the group without both measles vaccination and incidence history, being at 5877.60 (95% CI = 4450.41 ~ 7762.47).5. The prevalent wild strain of measles in Quanzhou belonged to new genotype H1 and gene subtypes H1a , matching the dominant genotype popular in the China mainland;The neutralization level of antibody produced by vaccine Immunization against the wild strain virus was lower by at least two titers than against vaccine strain virus, as suggesting antigenic drift may have occured in prevalent wild strain virus . 6. The measles vaccination rate of local children was maintained at over 90%; among floating children under the age of 7, measles vaccine inoculation rate of the first needle was 77.99% , the second-needle rate only 46.50%. Measles incidence decreased after the measles vaccination intervention. Conclusion Low vaccination rates and declining levels of population immunity against measles are major factors of increase in measles incidence, the poor management of infection sources is one of important factors in measles incidence. Effective measures should be taken to ensure than all children complete a measles vaccination course .Enhancing the management of the sources of infection remains the main measles prevention and control measures in Quanzhou. Emphasis should be made on strengthening immunization of floating child, and implementing the precheck and triage system in medical institutions at all levels to prevent iatrogenic infection.