[Prevalence of Neisseria meningitidis carriers in a school population in the metropolitan area of Madrid].

The prevalence of healthy carriers of Neisseriae meningitidis has been addressed by studying oropharynx samples of 1,172 schoolchildren in Madrid. The sample design took into consideration social status, age and sex. The total prevalence of healthy carriers was 2.30%, with 66% or these in the six year old age group (RR = 2.88, p < 0.005). Serotype B was found in 74% of the carriers, again mainly in the six year old age group, and 18.5% were serotype A, with most of them being found in the fourteen year age group. Serotype A carriers were females in 80% of the cases (p = 0.04). Serotype C was only found in six year old males. The prevalence of healthy carriers of Neisseriae meningitidis in our school-age population, in a non-epidemic situation, is in accord with results reported from other countries around us and agrees with previous reports of a higher prevalence among younger children and in males. In addition, the association between sex and some serotypes is confirmed.