Meningococcal Disease in Korea: an Epidemiologic Study of the Underestimated Infectious Disease

which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Editorial Meningococcal disease presenting with meningitis or sepsis is a life-threatening illness with significant morbidity and mortality worldwide. Despite providing appropriate antibiotic therapy and supportive care, invasive meningococcal disease could lead to death within a few hours to days, with a case fatality rate of 10-15% [1]. The incidence of meningococcal disease varies from 1 to 1,000 cases per 100,000 persons in different regions of the world. Age-specific incidence of meningococcal disease is the highest among children younger than 1 year; the second incidence peak is observed in adolescents and young adults of 15-24 years of age. The burden of meningococcal disease in Korea was reported to be relatively low based on the national notifiable diseases surveillance system, which reported an annual incidence of 0.01 to 0.08 cases per 100,000 persons [2]. However, the burden of meningococcal disease in Korea was expected to be substantially higher than that shown by the documented reports. It was difficult to understand me-ningococcal disease in the Korean population because of limited epidemiological data. Kang et al. [3] investigated age-specific seroprevalence of human serum bactericidal antibody (hSBA) titers against Neiserria meningitidis serogroups A, C, W-135, and Y in Korean adolescents and adults aged between 11 and 50 years nationwide. Their study could bridge the gap between surveillance data and actual burden of meningococcal disease. Their study suggests varied levels of natural immunity against the four serogroup meningococci, which reflects exposure to meningococcal capsular antigen. Meningococci are transmitted only from one human to another by infected respiratory secretions or saliva via airborne respiratory droplets usually under crowded living conditions. After exposure, it colonizes the oropharygeal mucosa known as carriage. The immune response elicited by the carried meningococci results in protective antibody responses [4]. In their study, protective antibodies with hSBA titers ≥8 were highly prevalent (74%) in serogroup W, and the lowest prevalence was observed in serogroup A (9%). To understand seroprevalance of N. meningitidis in Korean population, the carriage state needs to be investigated. Although carriage state was not included in that study, recent findings in carriage-related studies were slightly different from that in the seroprevalence study. A carriage related study among freshmen living in a Korean university dormitory showed that serogroup C was the most prevalent serogroup among groupable isolates [5]. Another study