In this age of serotherapy and prophylaxis the question of immunity is one of prominence. Typhoid is a prevalent and constant disease. Its causation and its avenues of attack are comparatively well known. No one to-day disputes the fact that a characteristic bacillus most commonly water borne and cultivated in the intestinal canal is the prime cause, but there has been a question in the literature of typhoid regarding the immunity of infants under one year old.
Previous to 1840 infantile intermittent fever was a commonly described disease with nurslings. About this time, 1840, Rilliat and Taupan each independently published articles to show that what was previously described as infantile intermittent fever was in truth typhoid fever. I have not been able to discover exactly on what Rilliat and Taupan based their deductions.
We find, however, in 1847, Condie, in his book, "Diseases of Children," saying: