Prevalence of meningococcal carriage in children and adolescents aged 10-19 years in Chile in 2013.

In 2011, Chile experienced an increase in the number of cases of IMD caused by Neisseria meningitidis group W. This epidemiological scenario prompted authorities to implement prevention strategies. As part of these strategies, the Institute of Public Heath of Chile conducted a cross-sectional study to determine the prevalence of pharyngeal carriage of N. meningitidis in a representative sample of healthy children and adolescents aged 10-19 years. The identification of presumptive N. meningitidis strains was performed by testing carbohydrate utilization in the National Reference Laboratory at the ISP. Association of meningococcal carriage with risk factors was analyzed by calculating the Odds Ratio. Selected variables were included in a logistic model for risk analyses. The prevalence of carriage of N. meningitidis was 6.5% (CI: 5.7-7.3%). Older age (carriers: 14.2±0.29 vs. non-carriers: 13.8±0.08 years old; p=0.009), cohabitation with children (carriers: 0.9±0.13 vs. non-carriers: 0.7±0.03; p=0.028), number of smoking cohabitants (carriers: 0.55±0.13 vs. non-carriers: 0.44±0.03) and frequent attendance to crowded social venues (carriers: 49% vs. non-carriers: 37%; p=0.008) were determined to favor carriage. Statistical modeling showed that meningococcal carriage was associated with older age (OR: 1.077, p-value: 0.002) and cohabitation with children (OR: 1.182, p-value: 0.02).

Neisseria meningitidis ST-11 clonal complex, Chile 2012.

Serogroup W Neisseria meningitidis was the main cause of invasive meningococcal disease in Chile during 2012. The case-fatality rate for this disease was higher than in previous years. Genotyping of meningococci isolated from case-patients identified the hypervirulent lineage W:P1.5,2:ST-11, which contained allele 22 of the fHbp gene.