IMPOETANOE OF EAELY DIAGNOSIS. 



The knowledge that we now have of the transmission of yellow 

 fever gives us a secure basis upon which to lay our plans against the 

 Introduction of the disease or to prevent its spread when introduced. 

 There is, however, one link wanting to give us absolute control of the 

 disease, and that is the etiological factor. The consensus of opinion 

 up to the present time is that it is a micro-organism, ultramicroscopic, 

 and as yet beyond our means of detection. The importance of deter- 

 mining this causative agent is apparent from every point of view, but 

 especially so as an aid to diagnosis, for the prompt and positive diag- 

 nosis of yellow fever is one of the most important factors in the pro- 

 phylaxis of the disease, especially when it appears in a locality where 

 it was previously unknown or that has been free of it for some time. 



In order to take measures against the spread of a disease it is first 

 of all necessary that we should be aware of its presence. In the case 

 of yellow fever considerable embarrassment presents itself in deter- 

 mining this fact, both on account of the inherent difficulty in making 

 the diagnosis and the natural fear of the attending physician of the 

 alarm and other unfortunate consequences which will usually follow 

 a declaration of its presence, and especially the fear that he may be, 

 after all, mistaken in the diagnosis. This applies particularly to 

 those localities where yellow fever is a new or an infrequent visitor 

 and where there exists an unreasonable fear of the disease. 



It is foreign to the purpose of this paper to enter into a discussion 

 of the differential diagnosis of yellow fever, but I desire to impress 

 upon the reader the importance, from a prophylactic point of view, 

 of the early diagnosis of all cases of this disease. We know that the 

 Stegomyia calopus can only become infected by biting the patient 

 during the first three' days of the illness; hence the diagnosis should 

 be made in its very incipiency. Frequently it is not easy to do this, 

 especially in mild cases. It is here that our knowledge is at fault and 

 all our energies should be bent to discover some means of making a 

 positive diagnosis, one which can not be controverted. When this is 

 achieved the citadel will have been won and the last vestige of 

 danger from this disease removed. 



USUAL CONDITIONS WHEN YELLOW FEVEE IS DEOLAEED. 



Under present circumstances the following conditions almost inva- 

 riably confront us in an outbreak of yellow fever in a locality usually 

 free from it, such as, for instance, our South Atlantic and Gulf 

 coast: A case of fever presents itself to a physician who is not on 

 the lookout for yellow fever and who perhaps has never seen the 

 disease. If it be a* mild case of yellow fever, it will probably get 

 well without his suspicions being even aroused. If, however, it be 



