YELLOW FEVER EXPEDITION 
509 
in the city that are chiefly attacked ; whilst in the great foci of paludism outside 
the city, and especially outside the municipal limit, febre remittente biliosa is very rare. 
In giving points for differential diagnosis from yellow fever, he says that 'the presence 
of an epidemic of yellow fever should always form a point for differential diagnosis' ; 
supposing that the relationship to yellow fever is more essential, the disregard of 
such cases would be just apt to foster the yellow fever and to ensure its reappearance. 
Guiteras 1 makes the following significant statement : ' The bilious remittent 
fever, that in our old text-books of medicine occupied so conspicuous a place in 
tables of differential diagnosis with yellow fever, has practically disappeared from 
the Southern Sea border since yellow fever ceased to be endemic there.' It is clear 
that in endeavouring to rid a neighbourhood of the yellow pest, notice and suspicion 
must be cast upon cases in which this other diagnosis is made, and they must be dealt 
with accordingly. Domingos Freire isolated a colon-like bacillus as the cause of the 
bilious fever, but said nothing concerning the malarial parasite ; which, however, may 
occur in mixed yellow fever and malaria. On the other hand, Azevedo and Couto 
look upon this bilious fever as a clinical form of malarial ( ' haemoglobinuric 
palustral') fever with icterus. It remains to be seen whether the condition is 
due to some further implantation in an old malarial patient of other organisms 
than that of malaria ; naturally the mere presence of the malarial parasites will not 
exclude the possibility of other factors. 
It is generally stated that second attacks of yellow fever are rare, and that there- 
fore the immunity against the disease is very complete. However, it is also commonly 
accepted that this immunity breaks down if the individual is long absent from infected 
regions, so that in reality it would appear that the acquired immunity is of com- 
paratively short (say a few years) duration ; constant exposure or rather constant 
reinfection is therefore essential for continuance of immunity. It is not to be 
expected that a typical attack will occur in a partially immune individual unless he 
has received a very severe dose of the infective agent. 
The following example is one of a not very typical attack occurring in an 
individual who had had yellow fever twelve years before at Pernambuco, and who 
had been engaged since in and about Brazil. Taken ill suddenly in the afternoon 
with rigor, temperature 101 0 , pulse 80, and took large dose of quinine. There was 
no typical facies ; some headache, much bilious vomiting, which continued for three 
days ; on the third day there was a trace of albumin in the urine, which soon cleared 
up. Temperature and pulse : — 
2nd day — morning temp., 102-6°, p. 86; afternoon temp., 102-6°, p. 88 ; 
3rd day— -morning temp., 103-6 ', p. 90; afternoon temp., 103-8°, p. 90 ; 
4th day — morning temp., 99-2° ; afternoon temp., 99-4° ; 
after which the temperature became normal. There was no icterus. Malaria parasites 
were not looked for on account of the quinine, but there did not seem any reason 
from the clinical side to suspect malaria. 
1. Guiteras, Report of U.S. Marine Hospital Service, 1898, p. 299. 
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