Risk of Subsequent Disease among Day-Care Contacts of Patients with Systemic Hemophilus Influenzae Type B Disease

There is controversy about whether to provide rifampin prophylaxis routinely to contacts in day-care facilities of a patient with a primary case of Hemophilus influenzae type b disease. We prospectively investigated primary cases of H. influenzae type b disease in day-care facilities in Dallas County, Texas, to determine the rate of subsequent disease among contacts. Ninety-one children with primary cases of H. influenzae type b disease who were attending day-care facilities were enrolled from October 1982 to October 1984. A total of 587 classroom contacts of these children under four years of age were not given rifampin. During 60 days of follow-up, there was one subsequent case in a classroom contact. Untreated children under two years of age who were directly exposed to a patient with a primary case were considered to be at highest risk of disease, but there were no subsequent cases in this group of 361 children. However, there were two cases in new enrollees who started attending day-care facilities during the 60-day follow-up period but who were not exposed to a patient with a primary case. At day-care centers in which there was a second case during the follow-up period, there was a high prevalence of colonization with H. influenzae type b in both patient and nonpatient groups of preschool children. These data indicate that the rate of subsequent disease in classroom contacts of patients in day-care facilities is lower than that reported in households (1 of 587 vs. 20 of 829, P = 0.001) and that this rate may be similar to the base rate of primary disease in day-care facilities. We conclude that rifampin prophylaxis may not be appropriate after the occurrence of a primary case of H. influenzae type b disease in a day-care facility in Dallas County. (N Engl J Med 1987; 316:5–10.) HEMOPHIL US influenzae type b is the most frequent cause of meningitis and other serious bacterial infections in children in the United States. 1 Young household contacts of patients with hemophilus disease have an increased risk of its development. 2 It is estimated that at least 50,000 children are exposed annually to a patient with this infection while attending day-care facilities. 3 Because households and day-care facilities provide similar opportunities for transmission of infectious agents and because clusters of cases have occurred in day-care facilities, 4 it has been hypothesized that children in day-care facilities are also at increased risk of disease after exposur