PREVENTION OF HEMOPHILUS-INFLUENZAE TYPE-B DISEASE

To determine the efficacy of rifampin prophylaxis in eradication of oropharyngeal carriage of H. influenzae type b and prevention of secondary H. influenzae type b disease, a multicenter placebo-controlled trial was conducted among selected persons with invasive H. influenzae type b disease. Households and day-care classrooms were randomized so that their members received either rifampin (initially at a dose of 10 mg/kg per dose for 2-4 days [rifampin-10], but subsequently at 20 mg/kg per dose for 4 days [rifampin-20]) or placebo. Pretherapy H. influenzae type b colonization rates were similar in the treatment groups. Therapy with either rifampin regimen significantly reduced carriage (rifampin-20, 97%; rifampin-10, 63%; placebo, 28%). New acquisition of carriage was also significantly reduced by either rifampin regimen (rifampin-20 or rifampin-10, 2% vs. placebo, 6%). No rifampin-resistant H. influenzae type b isolates emerged after treatment. Four of 765 placebo-treated contacts experienced secondary disease in contrast to 0 of 1112 rifampin-treated contacts. Because chemoprophylaxis of close contacts with rifampin seems to reduce significantly the risk of secondary H. influenzae type b disease, the administration of prophylaxis in households or day-care classrooms where children < 4 yr old were exposed to the disease is recommended.