In each country, informed consent will be obtained from adults selected to participate in the study and for the children under their care. Written informed assent will also be obtained from participants aged 12 to 15 years. Oral assent will be obtained from younger children. Once consent or assent has been obtained, a structured questionnaire will be completed following discussions with the head of the household which records information about sleeping and cooking arrangements in the household. Each study participant or their guardian will complete a questionnaire which collects information on potential risk factors for meningococcal carriage such as occupation, smoking, recent travel, including travel on the pilgrimage, attendance at social gatherings, and recent respiratory infection. Following interview, a pharyngeal swab will be obtained from each study participant. A 5 ml blood sample will be obtained from 200 randomly selected subjects in each of the four older age categories and from 50 infants aged 6 - 11 months (a total of 850 samples) during the initial survey to measure serogroup A bactericidal and Immunoglobulin G ELISA serogroup A, C, W135, X and Y meningococcal antibodies. Blood will not be collected from infants under the age of 6 months.