Underestimation of Invasive Meningococcal Disease in Italy

• DOI: 10.3201/eid2203.150928
• Publication Date: 2016-01-25T13:33:45Z
• Authors: Chiara Azzari; Francesco Nieddu; Maria Moriondo; Giuseppe Indolfi; Clementina Canessa; Silvia Ricci; Leila Bianchi; Daniele Serranti; Giovanni Maria Poggi; Massimo Resti
• Keywords: Adult; Male; 0301 basic medicine; Adolescent; Meningococcal Vaccines; Infectious and parasitic diseases; RC109-216; Neisseria meningitidis; Real-Time Polymerase Chain Reaction; Young Adult; 03 medical and health sciences; Humans; misdiagnosis; Diagnostic Errors; Child; underreporting; Retrospective Studies; Research; Incidence; invasive meningococcal disease; underestimation; R; Infant; 3. Good health; Meningococcal Infections; PCR; Italy; Italy; Neisseria meningitidis; PCR; bacteria; bacterial meningitis; invasive meningococcal disease; misdiagnosis; underestimation; underreporting; Adolescent; Adult; Child; Child, Preschool; Diagnostic Errors; Female; Humans; Incidence; Infant; Italy; Male; Meningococcal Infections; Meningococcal Vaccines; Real-Time Polymerase Chain Reaction; Retrospective Studies; Young Adult; Neisseria meningitidis; Epidemiology; Microbiology (medical); Infectious Diseases; Child, Preschool; Medicine; Female

Knowing the incidence of invasive meningococcal disease (IMD) is essential for planning appropriate vaccination policies. However, IMD may be underestimated because of misdiagnosis or insufficiently sensitive laboratory methods. Using a national molecular surveillance register, we assessed the number of cases misdiagnosed and diagnoses obtained postmortem with real-time PCR (rPCR), and we compared sensitivity of rPCR versus culture-based testing. A total of 222 IMD cases were identified: 11 (42%) of 26 fatal cases had been misdiagnosed or undiagnosed and were reclassified as IMD after rPCR showed meningococcal DNA in all available specimens taken postmortem. Of the samples tested with both rPCR and culture, 58% were diagnosed by using rPCR alone. The underestimation factor associated with the use of culture alone was 3.28. In countries such as Italy, where rPCR is in limited use, IMD incidence may be largely underestimated; thus, assessments of benefits of meningococcal vaccination may be prone to error.