WHICH CONTACTS OF PATIENTS WITH MENINGOCOCCAL DISEASE CARRY THE PATHOGENIC STRAIN OF NEISSERIA-MENINGITIDIS - A POPULATION-BASED STUDY

Objectives: To determine the prevalence of the pathogenic strain of Ne isseria meningitidis in contacts of patients with meningococcal diseas e, and to determine which contact groups are likely to be carriers and warrant chemoprophylaxis, Design: Population based study. Setting: No rwegian county of Telemark. Subjects: 1535 primary contacts of 48 pati ents with meningococcal disease, and 78 secondary contacts. Interventi ons: Carriers of the pathogenic strain were treated with rifampicin. A ll household members and kissing contacts under 15 years of age were t reated with oral penicillin. Contacts were taught to recognise the sym ptoms of meningococcal disease. Results: In 21 of 48 cases investigate d, contacts carrying the pathogenic strain of N meningitidis were foun d. A total of 42 such contacts were identified. Contacts were stratifi ed into three classes according to the assumed closeness of contact wi th patients. In class 1 (household members and kissing contacts) the p revalence of the pathogenic strain was 12.4% (95% confidence interval 5.5% to 19.3%). In classes 2 and 3 the prevalence was 1.9% (0.9% to 3. 4%) and 1.6% (0.14% to 3.1%). Conclusions: There is a high rate of car riage of the pathogenic strain of N meningitidis in patients' househol d members and kissing contacts, and this supports the practice of givi ng chemoprophylaxis to these contacts. The prevalence of carriage amon g other contacts is 2-3 times that found in the general population (0. 7%); the benefits of chemoprophylaxis to these contacts may be margina l.