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however, end between the fourth and the ninth day; after that date, 

 therefore, the chances of recovery are increased. 



Distribution of the three Clinical Forms. — The relative frequency of 

 the three forms of yellow fever varies in different epidemics, but the 

 following proportions may be taken as an approximate estimate among the 

 civil population of Havana in private practice. The majority of the cases 

 are probably "non-albuminuric", and the balance "melano-albuminuric." 

 The number of the latter appears to be, in some measure, dependent on the 

 treatment instituted at the onset of the attack. Among the military and 

 in certain classes of the civil population, the proportion of severe cases 

 must be greater owing to their being treated for ordinary complaints in 

 hospitals where yellow fever patients are at the same time admitted, and 

 the chances of infection from the worst forms of the disease must be thereby 

 increased. 



Diagnosis. — During the period of invasion, and before any signs of 

 albumen are likely to appear in the urine, the diagnosis can often be made 

 with a tolerable degree of probability, provided that the symptoms are 

 sufficiently characteristic; but a positive differential diagnosis is rarely 

 possible at that early date, specially if eruptive fevers, typhoid, or in- 

 fluenza, prevail at the same time. It happens, too, that the invasion of 

 yellow fever is sometimes preceded by one or two accessions of intermittent 

 fever, which might easily throw the physician off his guard. It is therefore 

 a safe rule in yellow fever countries, and during an epidemic, to look upon 

 every doubtful fever as possibly connected with that disease. This 

 suggestion, so far as disinfecting the alimentary canal is concerned, can 

 always be acted upon without inconvenience, even if other indications have 

 to be attended to. 



With the appearance of albumen in the urine between the second and 

 the fourth day of a continued fever, the diagnosis, in Havana, is considered 

 to be established. Black vomit in its characteristic forms may, as a rule, 

 be considered as a decided confirmation of the diagnosis, though it cannot 

 be said to differ (microscopically, at least) from some few samples which 

 I have obtained on rare occasions from cases that had no presumable 

 connexion with yellow fever. Black vomit is, moreover, a characteristic 

 symptom in a form of fever which, in Cuba, attacks native children, and 

 regarding which the profession is divided as to its relations with yellow 

 fever or malaria (the former being probably the correct view.) 



Next in importance among the diagnostic signs may be ranged the 

 thermometric curve, with a remission between the third and fourth or fifth 

 day, and defervescence (below 37° C.) between the fifth and the eighth. 

 Indeed, some of the "non-albuminuric" cases have to be diagnosed upon 

 this feature alone. A haemorrhagic tendency, even when very slightly 

 marked between the third and the seventh day, constitutes a valuable sign 



