| ObjectiveTo investigate the epidemiology of invasive meningococcal disease occurred in Hefei city during2000-2010and guide rational use to control this disease.To study the clinical characteristics of cases infected with serogroup C by compareing clinical data between serogroup C disease with serogroup A disease.To understand molecular biological characteristics of neisseria meningitidis (N. meningitidis) isolate strains of serogroup C、B and serogroup A by MLST in Hefei city.Materials and MethodsThe study was based on the National Notifiable Disease Surveillance System in Hefei city. We conducted national laboratory-based surveillance for invasive meningococcal disease during2000-2010.We study the epidemiology data of all cases with invasive meningococcal disease.reported to the Center for Disease Control (CDC).the test results of specimens (e.g., CSF, blood, and isolate strains) were analysed.We calculated the incidence on the basis of the number of laboratory-confirmed cases reported each year from1January through31December divided by midyear population estimates for each year, as supplied by Statistics Hefei city. In2006, the estimated population of Hefei city was1.85million. Serogroup-specific disease rates were calculated assuming that the distribution of serogroups.We reviewed the available medical information of all cases which were reported to Hefei CDC during1January2000to30December2010. The captured data included patients’history,clinical manifestations and complications, laboratoryresults,therapy, and outcome.Patients were categorized as either meningitis or meningococcemia. Because serogroup A has specific epidemiological features and a history of predominance in Hefei city. The prevalence of other serogroups in the area did not vary over time and caused minimal disease,so serogroup C disease was compared with serogroup A disease alone.50sreogroup meningococcal strains isolated from1990to2010in Hefei city were characherized by multilocus sequence typing (MLST)ResultsDuring the period of2000-2010,the were emergence of endemic meningococcal disease.with a total of845cases of invasive meningococcal case.The annually average incidence increased to4.15cases per100,000population. During the three yeas of2000-2002, the incidence keep relative low with1.19-1.57cases per100,000. Rates of reported disease increased from1.25cases per100,000population in2000to3.14cases per100,000population in2003(P<0.001). The incidence of invasive meningococcal case increased obviously and incidence arrived to6.92-8.43cases per100,000during2004-2007. The incidence was6.92cases per100,000population (2004.),8.43cases per100,000population(2005)、7.24cases per100,000population (2006) and7.08cases per100,000population (2007).Duing2008-2010, the annually average incidence was2.93cases per100,000population, experiencing some decrease than that of2004-2007, but still2.5times than that of2000-2002.Endemic meningococcal disease was mainly the result of a increase in the incidence of serogroup C disease. The percentage of cases of disease caused by serogroup C increased from9%(2of23cases)and0.11cases per100,000population in2000to57%(33of58cases) and1.76cases per100,000population in2003(P<0.01).During2004-2007, the incidence of serogroup C kept at5.57-6.05per100,000population, In the later part of the study period(2008-2010), the incidence of serogroup C decrease to0.92-3.14, still higher than the numbe before2003. During the same time,the incidence of serogroup A disease remained stable and proportion of serogroup A cases fluctuated markedly by year.For the period2000-2002, a total of59(80%) of74cases of disease were due to serogroup A, with the number decreasing to22(38%) of58cases in2003. During2004-2007, the percentage of serogroup A keeped relatively lower level at10%-15%.During the11-year period reviewed,584(69.1%) of845cases were caused by serogroup C, whereas208cases (24.6%) were occurred to serogroup A. The distribution across age groups was different between serogroups C diseases and sreogroup A diseases.For patients with serogroup C disease, the median age and average were respectively19years (interquartile range,6months-78years)and17.4years, compared with6.9years (interquartile range,2months-31years) and2years, respectively, for serogroup A disease(P<0.05). A higher proportion of serogroup C disease occurred in relatively older age groups.The highest incidence(13.57cases per100,000) and highest rates(43.0%) for serogroup C were the15-24-year age group,compared with the highest incidence(6.16cases per100,000) and highest rates (54.8%) for serogroup A in the1-4-year age group.During the11-year period we analyzed,a total of374meninggococcal strains were isolated and90%of meninggococcal strains were susceotiable to ceftriaxone, cefotaxime and meropenem. Meninggococcal isolates of serogroup A strains kept high susceptible to penicillin,arriveing90.7%(88/97), correspondingly, the susceptible rate only was80.7%(213/264) for serogroup C strains(P=0.023).SMZco had the same condition with91.9%serogroup A strains sensitive and85.2%serogroup C resistant.Complete detailed clinical information was available on84%(493/584) of patients with serogroup C and85%(177/208) of patients with serogroup A. Serogroup C disease was found to be more likely to cause meningococcemia (76.9%vs.48.0%;OR:3.60;95%CI:2.51-5.17; p<0.001). Patients in serogroup C were significantly more likely than those in serogroup A to have shock(18.5%vs7.3%; p<0.001) and DIC(12.2%vs.4.0%;p=0.002). It suggested that patients infected with serogroup C were severe and more frequently involved in seroious complications.There was enough information to objectively assess sequelae in655survivors. About nine percent of serogroup C cases (46of484cases) and4%of serogroup A cases (6of171) were affected (P=0.013) During the period of study,a total of64fatal cases were reported to Hefei CDC. It was mainly resulted from increasing death cases caused by serogroup C disease. And case-fatality rates of serogroup C meningitis was11.4%, which was significantly higher than it for serogroup A meningitis (5.3%, P=0.021). Factors associated with death in univariate analysis were age of15-24years, infection with serogroup C, and meningococcemia. In multivariable analysis, age group and meningococcemia were significantly associated with death.There was a marginal association between serogroup C infection and increased risk of dying (adjusted OR,2.73; p=0.052)Ten sequence types (STs) were identified in20strains of serogroup C.The main ST was ST-4821and ST-4821complex was the most prevalent lineage for serogroup C(17/20).These study also showed a high level of ST-5(belong to ST-5complex) for serpgroup A(14/20)and also remained diversification for serogroup A isolates, as indicated by the number of variants of the ST-7(5/20) and ST-1(1/20).Complexing trend of ST-4821in serogroup B also was found in this study because50percent STs were identified to ST-4821for10strains serogroup B.The results of this study allow us to draw a profile of the molecular characteristics of N.meningitidis strains in Hefei city.These data are helpful for monitoring the spread of virulent strains and will provide valuable information for the prevention of bacterial meningitis in China.ConclusionsThe incidence of meningococcal disease has substantially increased and serogroup C has become endemic in Hefei, causing disease of greater severity than did the previous predominant serogroup A strain. The main ST was ST-4821and ST-4821complex was the most prevalent lineage for serogroup C. |
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