Prevalence of asymptomatic carriers of Neisseria meningitidis among medical students at the University of São Paulo, Brazil

Abstract

Meningococcus is a major cause of bacterial meningitis and sepsis worldwide. Invasive meningococcal diseases are caused by a limited number of strains while isolates from the nasopharynx of asymptomatic carriers belong to multiple lineages, many of which are not associated with meningococcal disease. Despite the high rates of asymptomatic nasopharyngeal carriers in the population, the disease is rare. In Brazil, in 2009, the incidence rate of meningococcal disease was 1.36 cases/100.000 inhabitants, 12.58 cases/100.000 infants under one. Most studies of asymptomatic carriers in the world show that the main carriers of meningococcus are young adults between 15 and 24 years of age. This population is responsible for meningococcal transmission. In September 2010, the meningococcal C conjugate vaccine was introduced in the routine of the Brazilian National Immunization Program for children under two years, the age group with the highest meningococcal disease incidence rates. In the UK, the vaccination of the population between 0 and 19 years of age resulted in a significant reduction in the meningococcal carrier state in young adults, reducing the transmission and the number of cases of disease in all ages (herd protection). There is no data on asymptomatic carriers of Neisseria meningitidis in a Brazilian setting. Data on the rate of asymptomatic nasopharynx carrier are essential to understand the epidemiology of the disease and to direct public policy on vaccination. (AU)