YELLOW FEVER EXPEDITION 
49 1 
It is commonly stated that one attack of the fever confers a long and lasting 
immunity against further attacks. The completeness of this immunity, however, is 
called in question by the cases which we had the opportunity of seeing. Thus out of 
the two or three dozen cases we saw, no fewer than four were reputed to have had 
previous attacks ; the previous attacks were not believed in as genuine yellow fever 
by those physicians who accept a rigid immunity as the fact. A tew words may be 
said of one of these cases as illustrative of several points : — 
' A lady had an attack of yellow fever in New Orleans, at the age of nine- 
teen, in 1866 ; her account of the symptoms she experienced, and the fact that 
her sister had a " typical " attack at the same time tend to the conclusion that 
the illness was indeed yellow fever. Last year she was occupied as an " immune " 
in nursing yellow fever cases in Cuba during July and August, and then re- 
mained in the outskirts of Havana (Cerro) for the winter and spring. This 
summer she went to live in an insanitary house close to the hotel we have 
already alluded to as an infected house, situated in an " infected " neighbour- 
hood. She soon contracted an illness of the nature of which there could be 
no doubt — a severe and prolonged attack of yellow fever.' 
But our knowledge of infectious diseases all goes to show that a complete and 
absolute immunity is never acquired by a single attack, though second attacks are 
usually of a comparatively mild, or at any rate recoverable, type. 
The coloured people and natives are also supposed to escape the disease, but we 
are informed that this is a statement which is not true, although so frequently re- 
peated in text-books. We were lucky enough to see one negro during the course of 
a typical attack. The Cubans and the Cuban doctors are in the habit of asserting 
that the Cuban system is not capable of having yellow fever. It appears, however, 
that they are not unknown to suffer from a disease called ' borras.' Clinically 
' borras ' is like yellow fever — sometimes with black vomit and death with suppression 
of urine ; pathologically the lesions of yellow fever are said to be present in fatal 
cases. The Cubans also suffer and die from ' pernicious malarial fever,' the sympto- 
matology and pathological anatomy of which are very suggestive of yellow fever. 
We were informed that the Cuban children frequently suffer from mild attacks of 
fever, which our informants believe are really mild attacks of yellow fever, and which 
give a comparative immunity in after-life. 
It has already been mentioned that a sojourn of a non-immune for some hours 
in an infected house is very likely to lead to an attack ; and that this is supposed to 
be especially the case at night. Since many of the cases we saw were soldiers, their 
movements could be traced to some extent, and in more than one instance there was 
evidence of a single exposure after breaking bounds for a single night. Similar ex- 
periences are told of ship's crews under similar circumstances ; another example is to 
be found in the case of one hundred American military prisoners who were confined 
