Twenty years ago it was generally agreed that typhoid fever rarely developed in children under the age of five years. The reason for this supposed comparative immunity was often discussed and it was generally accepted that even the fact of the simpler diet of such children causing little irritation and consequently providing fewer opportunities for the invasion of the disease, was not of itself sufficient to account for its comparative rarity. The assumption of some special protective factor as specific immunity seemed necessary to explain the infrequency of typhoid fever in young children. From more careful observation and more scientifically exact diagnosis, it has developed that this supposed immunity is only imaginary. Children of any age, except for the protection afforded by their fewer opportunities of infection, are just as liable to contract typhoid as older people.
Eichhorst1 says that the transmission of typhoid bacilli from the mother to