Epidemiological analysis of measles in Loudi City of Hunan Province from 1978 to 2006

Objective The study was conducted to explore the epidemiological characteristics of measles in Loudi City and to provide scientific bases for effective measles control.Methods Measles cases were notified through the surveillance system;serum samples were collected and tested by ELISA to detect measles IgM and IgG antibodies.Analyses were conducted using Excel and SPSS.Results 32 642 measles cases were reported from 1978 to 2006,the average annual incidence being 30.71/lakh.Significant differences were observed in incidence rates of different districts/counties and of different time periods.The epidemic trend went ascending,then declining and finally returned,and could be divided into 3 periods.After the three major peaks in period I,the epidemic continuously declined from 1987 to 2000 until a minor peak recurred in 2004.79 deaths with a fatality rate of 0.24% were reported in the 29 years.Cases were mostly reported in March to June from 1991 to 2006,while in 2004 when the incidence rate re-ascended,peaks were seen during February to April.60.47% of the cases occurred in children under 5 years old and dispersed children accounted for 55.48% of all the cases.Measles vaccination coverage rates ranged from 71.50% to 99.76% in the 29 years,which were negatively correlated with the annual incidences.The total antibody positive rate was 91.18% in serologic surveillance.Among the cases reported from 2005 to 2006,only 15.30% of them had a clear history of vaccination.Conclusion The incidence rate of measles decreased 89.14% in Loudi,while in recent years a recurring increase was seen,which may have resulted from relatively low immunization coverage and gaps in population immunity.In recent years of high epidemic,onset seasons became earlier with stronger epidemic strength,and characterized by a little-age epidemic pattern.