THE EHRLICH DIAZO REACTION^'^ 



By James R. Arneill, A. B., M. D., 

 Associate Professor of Medicine, University of Colorado 



In a preliminary report of the commission appointed by Surgeon- 

 General Sternberg to investigate typhoid fever during the late war, 

 Vaiighan states that the chief difficulty with which the commission 

 had to contend was the utter worthlessness in numerous instances of 

 the diagnoses of the volunteer physicians. As a result of inability 

 and lack of opportunity to make blood examinations for plasmodia 

 malaria and Widal's test for typhoid fever, thousands of cases of 

 typhoid fever were diagnosed malaria, typho-malaria, continued fever, 

 dengue, indigestion, and diarrhoea, and treated as such. 



It may seem an extravagant statement, but it is none the less 

 true, that if the diazo test had been applied in a routine way, and 

 alone depended upon for the diagnosis of typhoid fever, the vast ma- 

 jority of these cases would have been correctly diagnosed. 



Before recording my observations and deductions in detail, I will 

 give a short resume of the history and the chemistry of the diazo re- 

 action. 



In 1860, Peter Griess discovered and produced the azo dyes. 

 He early made use of sulphanilic acid and naphthylamin salts for the 

 demonstration of nitrous acid and its salts by means of color re- 

 actions. In 1875 the chemist Weselsky demonstrated phloroglucin 

 by combining it with nitrodiazobenzol, the product being a red dye. 

 Ehrlich believed that in the urine of certain diseases aromatic bodies 

 were excreted which would become diazotized under proper chemical 

 treatment. With this idea in mind, in 1882 he experimented upon 

 the urines of a large number of infectious and non-infectious diseases, 

 and obtained a specific diazo reaction, especially in the urines of ty- 



(M Reprinted by courtesy of the editor of The American Journal of the Medical Sciences, 

 March. 1900. 



