Meningococcal carriage prevalence in university students, 1824 years of age in Santiago, Chile
Introduction
Meningococcal invasive disease is unique to human beings. It is a major public health problem given its global distribution, epidemic potential and short and long-term morbidity [1], [2], [3]. It has an unexpected initiation, an unpredictable evolution and sometimes a fulminant course, mainly in healthy infants and adolescents [3]. It has an overall incidence ranging from rates below 0.5 to 1000/100,000 population per year depending on the evaluated geographical area [4], [5], [6]. The epidemiological situation in Chile has been classified as “low endemicity” since 2001, with an annual incidence of 0.5/100,000 inhabitants [7], mainly serogroup B. As of 2010, the country has experienced a gradual increase in serogroup W cases, with a clear predominance of this serogroup from 2012 onwards [7]. Despite important advances in diagnosis and intensive care management, case fatality rates remained stable since 1930 between 8% and 14%, and increased in 2012 up to 25% parallel to the serogroup W ST-11 clonal complex circulation [3], [10].
Neisseria meningitidis is part of common nasopharynx flora and is present in about 3–25% of the general population, which is known as pharyngeal carriage [4], [5], [8]. This successful, dynamic and time variable relationship between the microorganism and the host is considered an important source of infection for susceptible individuals [5], [9]. The pharyngeal carriage prevalence varies by age group, from 0.7% in children under 4 years up to 32% among young people aged 20–24 years [3], [4].
Several carriage risk factors have been described, such as age, male sex, overcrowding, active and passive smoking, alcohol consumption and number of kissed people, among others [4], [10], [11].
The relationship between carriage prevalence and invasive disease incidence is not clearly understood. However, carriage studies can provide valuable information on epidemiological basis, pathogenesis, serogroup distribution, transmission patterns and hyperinvasive strain detection. All this helps understand the potential effects of control programs, such as vaccination and antimicrobial treatment opportunity [10], [12].
Latin American data shows a pharyngeal carriage prevalence of 1.9% in children and 2.9% in adolescents in Mexico [11], [13] and 1.5% in schoolchildren in Venezuela [13]. Chilean information goes back to 1979, with a described prevalence of 12% in 2–15 year old subjects; no data have been published since [14].
The aim of this study was to estimate the meningococcal pharyngeal carriage prevalence in healthy university students aged 18–24 years in Santiago, Chile. Secondary endpoints were to assess the presence of known pharyngeal carriage risk factors and to identify and sequence serogroups in the isolated strains.
Section snippets
Overview
Cross sectional study, held in Santiago, Chile, during October 2012. We recruited 500 healthy individuals, all university students belonging to different faculties of Universidad de Chile, between ages 18 and 24 years old. Exclusion criteria: previous meningococcal disease, chronic diseases such as diabetes, kidney or liver disease, congenital or acquired immunodeficiencies (hemato-oncological diseases, systemic corticosteroids for longer than seven days, use of immunosuppressors), use of
Population
We enrolled 500 students from different faculties of the Universidad de Chile, during October 2012. The demographic characteristics of the study population are described in Table 1. The median age of study subjects (pc 25–75) was 20 years (18–24) and 50% were male. No students lived in dorms and 84% did not share their room. One hundred and two students (20.4%) belonged to high socioeconomic level, 174 (34.8%) to medium level and 224 (44.8%) to low level (P = 0.4). The educational distribution of
Discussion
The previous report of pharyngeal meningococcal carriage in Chile was published in 1979, 33 years before this study [14]. Currently, the prevalence found in a sample of university students between 18 and 24 years of age was 4%. Most strains were not capsulated, similar to previous reports. From these 20 isolated strains, 20% were serogroup B, of which only two corresponded to the clone ST41/44 and 15% were serogroup W without the presence of clone ST11 hyperinvasor, responsible for invasive
Conflict of interest
The authors declare no conflicts of interest.
Funding
This work had no funding sources.
Acknowledgements
Sampling: Rosario Berríos, Cecilia Concha, Verónica Contardo, Verónica de la Maza, Carolina Godoy, Pamela Lama, Rossana Mendies. Microbiology Laboratory Hospital Luis Calvo Mackenna: Gloria Donoso, Lorena Cifuentes, and Tatiana Arcos.
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