Meningococcal Disease: Epidemiology and Early Effects of Immunization Programs

Meningococcal disease (MD) is a major public health problem and remains an important cause of meningitis and sepsis in several Latin American countries. Most cases of MD are sporadic, with seasonal variations and outbreaks occurring at irregular intervals. Outbreaks are more likely to involve olderchildren and young adults, usually associated to increased case fatality rates (CFRs). During the last decade, incidence rates of MD varied widely in the region, from less than 0.1 cases per 100 000 in countries including Mexico, Peru, Paraguay, and Boliviato2c ases per 100 000 in Brazil, with the highest incidence generally observed in infants [1, 2]. The availability and quality of published data for MD are not uniform across the region, with limited data available and exceedingly low rates of MD reported by some countries [1, 2]. Serogroups B and C are responsible for the majority of cases reported in the region. However, an increased number of serogroup W disease cases, associated with the ST-11 complex, was recently reported in Argentina and Chile [2].According to the SIREVA program implemented by the Pan-American Health Organization and the World Health Organization, a total of 901 meningococcal isolates were characterized in 2012, of which 513 came from Brazil, 172 from Argentina, 100 from Chile, 30 from Colombia, 28 from Venezuela, and 24 from Uruguay. These 6 countries were responsible for more than 95% of the isolates reported in the region. Serogroup C was the prevalent serogroup, responsible for 44% of the meningococcal isolates characterized; serogroup B was responsible for 29%; serogroup W was responsible for 20%; and serogroup Y was responsible for 5% [3].