Epidemiology of invasive meningococcal disease in Austria 2010.

Introduction: Neisseria meningitidis is a leading cause of meningitis and sepsis worldwide. Thus, monitoring the epidemiology of invasive meningococcal disease (IMD) is an important public health measure. The National Reference Centre for Meningococci at the Austrian Agency for Health and Food Safety is operating the laboratory-based surveillance database.
Methods: IMD isolates from all over Austria are collected at the National Reference Centre for Meningococci, where the microorganism is characterised by serological and molecular methods, as well as by antimicrobial susceptibility testing. These laboratory-based surveillance data from 1995 to 2010 were analysed by time, place and person. Long-term and seasonal trends were analysed by log-linear regression, yielding an annual average percentage change (AAPC), and by cyclic regression models, applying either a simple linear or a negative binomial regression, including one sine and one cosine term.
Results: Over the past 16 years, IMD incidence ranged between 0.73 and 1.41/100,000 persons, with a decreasing trend in Serogroup B IMD incidence (AAPC: -2.1%; p = 0.0396) and an increasing trend in Serogroup C IMD incidence (AAPC: +4.3%; p = 0.043). In 2010, 80 cases of IMD were recorded, corresponding to an incidence of 0.95/100,000 population. Ten deaths were registered, which results in a case-fatality of 12.5% and a mortality incidence of 0.12/100,000 population. The predominant serogroup in Austria was serogroup B, followed by serogroups C, Y and W-135.
Discussion: Although the incidence of IMD in 2010 is below the average incidence rate over the last 15 years, serogroup C IMD in Austria is increasing. Within the previous 10 years two provinces initiated vaccination campaigns for a monovalent meningococcal conjugate vaccine, following the increasing trend of Sg C IMD incidence. An ongoing study on the impact of these vaccination campaigns on the IMD burden will yield further scientific evidence for supporting the introduction of this vaccine into the publicly funded childhood immunisation program.