Analysis of current epidemiological and clinical characteristics for laboratory confirmed epidemic cerebrospinal meningitis cases in Shandong Province, 2007-2016

Abstract

Objective: To analyze epidemiological and clinical characteristics of laboratory confirmed epidemic cerebrospinal meningitis cases. Methods: Epidemiological and clinical informations and cerebrospinal fluid (CSF) and blood specimens of AMES (acute meningitis/encephalitis syndrome) cases were collected in the six sentinel hospitals from 2007 to 2016. neisseria meningitides (Nm) species and serogroup identification were detected by the methods of real-time fluorescent quantitative polymerase chain reaction (Real-time PCR) and bacterial culture, and epidemiological and clinical characteristics of laboratory confirmed epidemic cerebrospinal meningitis cases were analyzed. Results: 6 809 AMES cases were reported from 2007 to 2016. Total 4 422 cases were detected, and 90 cases were Nm positive. Through the methods of Real-time PCR, bacterial blood culture and CSF culture, the numbers of Nm positive cases were 90, 2 and 1 respectively. Twenty-two Nm cases were identified from 2007 to 2011 (4 cases were ungrouped), which with the highest incidence in serogroup C cases (17/18), and one cases was ungroupable Nm. Nm laboratory confirmed cases (68 cases) were increased dramatically and mainly occurred in serogroup B cases (43/67, 64.2%) from 2012 to 2016, with serogroup C cases highly decreased (5/67, 7.5%) and ungroupable Nm cases increased (13/67, 19.4%) meanwhile. Serogroup W135 and X cases were first detected at 2012 and 2014, and serogroup A remaining a low level which only detected one case at 2013. The morbidity of epidemic cerebrospinal meningitis was occured in the whole year, and mainly in winter and spring. The ratio of Nm laboratory confirmed cases to AMES cases during November to May (3.5%, 67/1 920) was higher than that during June to October (0.9%, 23/2 502) (χ(2)=34.45, P<0.001). Most Nm cases were children, students and farmers, and account for 30.0% (27/90), 31.1% (28/90), 18.9% (17/90), respectively. The majority of Nm cases were under 20 years old (60/90, 66.67%), and serogroup C cases (17/22, 77.3%) mainly occurred in over 12 years old population, while serogroup B (24/43, 55.8%) and ungroupable (6/14) cases mainly occurred in under 12 years old population. The main clinical symptoms of epidemic cerebrospinal meningitis cases were fever (78/90, 86.7%), headache (59/90, 65.6%) and vomiting (51/90, 56.7%). Misdiagnosis rate of admitting diagnosis was up to 87.8% (79/90) for the reason of atypical features in specific symptoms and blood or CSF positive index. The well-healed ratio in correct diagnosed group (7/11) was higher than that in misdiagnosed group (2.5%, 2/79) (χ(2)=40.61, P<0.001). Conclusion: The clinical symptoms of epidemic cerebrospinal meningitis cases were atypical, and the diagnosed sensitivity and accuracy would be improved by enhanced molecular biology detection. The predominant epidemic serogroup of Nm switched from serogroup C to B, and the key work was surveaylance of serogroup transition.