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this type, nevertheless a clue to their nature will, as a rule, be discov- 

 ered if a careful study of a series of cases be made. In a group some 

 individuals are very likely to be found that will show, if they are yel- 

 low fever, unmistakable jaundice and a degree of albuminuria quite 

 out of proportion to the mildness of the attack, whereas, if they are 

 dengue, some cases will be found that will exhibit the ' characteristic 

 rash. In isolated instances, or until cases' presenting distinctive symp- 

 toms are encountered, the observer will do well to suspend judgment 

 and not assume, as is too frequently done, that mildness of attack and 

 a failure to die are pathognomonic of dengue. He should remember, 

 also, that the two diseases may occur side by side, thereby multiplying 

 the difficulties of the problem and rendering caution imperative. 



Grippe. — An attack of influenza is characterized, as a rule, by 

 symptoms referable to a catarrhal condition of the upper air pas- 

 sages. Cases in which these symptoms are marked hardly come into 

 consideration in the diagnosis of yellow fever. As with dengue it is 

 the less well-defined cases of influenza that counterfeit and are simu- 

 lated by mild and ill-defined cases of yellow fever; and much that has 

 been said concerning the diagnosis from dengue is here also applicable. 



Bvbonic plague — In localities where yellow fever and plague pre- 

 vail, and at quarantine stations in connection with vessels from such 

 ports, the question of differentiating the two diseases may arise. 

 Clinically there is only a very superficial resemblance between the 

 two, but in all cases of doubt a careful bacteriological examination 

 should be made of the sputum, blood, or aspirated juice from enlarged 

 glands; the latter, by the way, are but very rarely met with in uncom- 

 plicated yellow fever, while in plague they are not only enlarged but 

 inflamed and the surrounding tissue infiltrated. * 



Typhoid fever. — Early in the disease typhoid may be mistaken for 

 yellow fever, but the resemblance is slight and observation of the 

 patient for 3 or 4 days will be certain to resolve any doubts. At 

 this stage the general appearance and the increasing apathy of the 

 patient are distinctive. The°temperature is a gradually ascending one 

 or has reached the fastigium, and the pulse, though not fast, follows 

 the daily oscillations of the fever and does not, as in yellow fever, 

 tend to become slower from day to day. Jaundice is, at best, but a 

 rare complication of typhoid and may be said almost never to occur 

 early in the disease. The urine frequently gives the diazo reaction, 

 and at this time is usually free of albumin, though occasionally traces 

 of the latter constituent may be met with; nephritis is a late and not 

 common complication of typhoid fever. The bacillus of Eberth may 

 be isolated from the blood. 



In an attack of yellow fever of three or four days duration and with 

 a corresponding elevation of temperature the combination of symp- 

 toms distinctive of a well-defined attack of this disease would be clearly 



