"Contribution to the Question of Pneumotyphus": a discussion of the original article by J. Ritter in 1880.

In 1880, Dr. J. Ritter wrote a classic infectious disease article (originally in German) on psittacosis entitled, "Contribution to the Question of Pneumotyphus." In this article, Ritter meticulously describes a mini-epidemic--in which three individuals died--of seven cases of psittacosis caused by parrots and finches caged in the study of his brother's house in Uster, Switzerland. Ritter accurately identified the study as the site of the source of infection, considered the birds as vectors, and determined both the incubation period and the nontransmissability of the disease from human to human. His main differential diagnosis was a choice between typhoid and typhus; with pneumonitis being the main pathologic finding, he coined the term pneumotyphus. Ritter's article elegantly describes the clinical presentation, epidemiology, pathologic findings, and natural history of infection due to Chlamydia psittaci. Ritter's astute observations and their significance are discussed in this paper.