RESUMO
Objective To study the trends over time in meningococcal meningitis with Neisseria meningitidis .Methods Routine reported data on Meningococcal meningitis with Neisseria meningitidis in Shijiazhuang from 1949 to 2014 were used to study the trends of disease severity,disease distribution and serogroup switching of Neisseria meningitidis strains over time.The qualitative description and the quantitative evaluation was performed by the annual percent change (APC)in incidence to demonstrate the secular trends.The t test and χ2 test were performed when appropriate.Results From 1949 to 2014, 53 779 meningococcal meningitis cases were reported in Shijiazhuang.Of the 53 779 cases,36 170 were male and 17 609 were female,which was significantly different (χ2 =581 .04,P =0.000).It occurred all the year round,with an increased incidence between February and April,accounting for 81 .44%.The epidemic peak occurred about every 10 years.The range of annual incidence rate was from 0.01/lakh to 387.21/lakh.APC was -4.65 (t=-11 .72,P =0.000).The significant decline of APC were found in the age group of 0—1 year (t=-10.56,P =0.000),1 —5 year (t =-14.32,P =0.000),5 —10 year (t=-11 .01 ,P =0.003 ),10—15 year (t = -8.34,P =0.033 )and 40—50 year (t = -7.42,P =0.045).The risk population was those under 5 years old during 1949 to 2002 period and the serogroup was dominated by A strains.Whereas during 2003 to 2014,that was those of 5 —15 years old,and the dominant serogroup was C strains. Conclusions There is a remarkable decline in incidence of meningococcal meningitis in Shijiazhuang.The serogroup changes from A strains to C strains and the risk population of cases shifts to older children.