ACUTE INFECTIOUS DISEASES. 



domiiial typhus as a higher grade, exanthematic typhus as a lower 

 grade of the infection with typhus poison, for there have been epidem- 

 ics of the latter that were more malignant than those of abdominal ty- 

 phus ; and even in the milder epidemics of exanthematic typhus, the 

 intensity of the symptoms, especially of the fever, was almost always 

 greater in the individual cases than in most cases of abdominal typhus. 

 While the fact that patients with varioloid often infect others with 

 variola, and vice versa, shows us that variola poison and varioloid poi- 

 son are identical ; the fact that persons infected by patients with ex- 

 authematic typhus always have that disease, never abdominal typhus, 

 shows us that the poison inducing the former is not identical with that 

 of the latter, and that, in spite of some similarity of symptoms, the twc 

 diseases are of different nature. If the resemblance between measles 

 and scarlatina were even greater than it actually is, the single fact, that 

 infection with measles poison never induces scarlatina, would suffice to 

 prove the non-identity of these diseases, and that the difference be- 

 tween them is not only one of degree ; but we shall not deny the 

 possibility that the two typhus poisons resemble each other more 

 closely than do those of scarlatina and measles ; nor shall we compare 

 the prevalence of one or other form of typhus, at certain times and 

 places, with the repeated epidemics of measles at certain times and 

 places, or with the almost exclusive occurrence of scarlatina epidemics 

 at other times and places. The belief in the relationship, or, to speak 

 more generally, in the resemblance of the poisons which induce exanthe- 

 matic and abdominal typhus, is supported by the similarity of the 

 causes favoring their development, as well as by the similarity of their 

 effects, that is, of the symptoms of the disease, as will appear from what 

 follows. 



I consider the extension by contagion, as well as by miasm, as even 

 more probable in abdominal than in exanthematic typhus, or (to speak 

 in a way that shall better show my position in regard to the views on 

 contagion and miasm), that the germs which cause abdominal, typhus 

 may develop and multiply as well in the organism of a typhus patient 

 as they would under favorable circumstances outside of it. It is true, 

 I cannot prove the correctness of this hypothesis, but I must also deny 

 that the recent assertions, that abdominal typhus spreads solely by 

 contagion, have been proved, or even rendered very probable, by the 

 facts adduced. 



The contagion of abdominal typhus is not so intense as that of ex- 

 anthematic typhus. There is no doubt that it clings particularly to 

 the dejections of the patient, and that persons exposed to the emana- 

 tions from typhus stools are most apt to be infected. On the other 

 hand, I consider it doubtful if the contagion be transferred by the ex 



