Diphtheria in the first year of life is rare, according to most authorities. Rolleston1 and Deacon2 found an incidence of 0.7 per cent in 2,600 and 31,000 infants, respectively; Baginsky3 reported an incidence of 0.15 per cent in 2,700 infants under 6 months of age. However, McCollum and Place4 give the incidence as 2.75 per cent. This rarity is variously attributed to (1) inherited immunity through placental transmission of antitoxin; (2) lack of exposure; (3) acid secretions in the infant's mouth, and (4) antitoxin transmitted through the mother's milk. Most textbooks merely make general statements concerning the relative immunity that is present in infants under 6 months of age.5 On the other hand, Ribadeau-Dumas, Lacomme and Loiseau6 claim that diphtheria in the new-born is uncommon only because it is often overlooked.
In 2,400 consecutive admissions for diphtheria on the contagious service of the Cincinnati
RAVENEL SF. DIPHTHERIA IN INFANCY. Am J Dis Child. 1927;34(2):258-262. doi:10.1001/archpedi.1927.04130200102012