Haemophilus type B meningitis in Saudi children under 5 years old.

This study was designed to determine the magnitude of bacterial meningitis in general and Hib meningitis in particular among children below the age of 5 years. A population-based, prospective descriptive and analytical study was conducted in five regions, one each in northern, southern, eastern, western, and central parts of Saudi Arabia. Active surveillance for cases of bacterial meningitis among the study population, which comprised 171,818 children under 5 years of age, was implemented. A total of 208 cases of meningitis were identified, of which 141 (67.8 per cent) were identified with a definite causative organism. The remaining 67 cases (32 per cent) were labeled as aseptic meningitis. The overall incidence of meningitis was 60.53/10(5) in under-fives with a disease spectrum similar to that reported in studies conducted in other countries. The three leading causes of meningitis were Hib (Haemophilus influenzae type B), MCM (Neisseria menigitides) and SPN (Streptococcus pneumoniae). Hib meningitis constituted 28 per cent of cases with an incidence rate of 16.88/10(5) children. There was a marked regional variation in Hib incidence. MCM was the second leading cause (18 per cent) of meningitis with an incidence of 10.77/10(5) while SPN comprised 11 per cent of cases and its incidence was 9.69/10(5). Almost all MCM cases were related to meningitis outbreaks that occurred in Saudi Arabia during two successive Hajj seasons (2000-2001). Hib cases showed a bimodal seasonality, one peak during March-May, the other during September-November. The fact that this study is the first national base-line data on meningitis in general and Hib incidence in particular, has augmented further justification for introducing Hib vaccine within the national Expanded Program on Immunization (EPI). Based on the experience gained during this study regarding surveillance of meningitis disease, optimal methods to strengthen meningitis surveillance were identified. A model of Meningitis Diseases Surveillance was generated that can be tested and then generalized. The study has documented beyond doubt the impact of Hajj seasons on MCM disease occurrence and further justifies the rigorous control and preventive measures being taken in this aspect.