In Reply.—Dr Sawyer's second patient falls in the category that we prefer to call coprimary rather than secondary. In our review of intrafamily spread of Haemophilus influenzae infection in confirmed cases, the time interval between the disease in the index case and siblings ranged from 24 hours to two months, with a mean time interval being 8.5 days. Our present policy is to diagnose H influenzae meningitis expediently by smear (80% to 85% positive) and counterimmunoelectrophoresis (90% to 95% positive). Once a diagnosis is made, we ask the parents to bring in the siblings. Cultures are taken from all siblings, and those under 3 years of age are given ampicillin, 100 mg/kg/day orally, for ten days. Using this regimen, we have not seen a secondary or coprimary case in two years. Siblings over 3 years of age, if culture positive, are also treated; the rationale here is to reduce