YELLOW FEVER EXPEDITION 529 
the diagnosis of Case 3 as yellow fever can also hardly be questioned. Case 4 has 
already been discussed ; Case 5 was also, probably, mild yellow fever, and was diag- 
nosed as such at the Hospital. 
Although it is not clear where the original infection came from, and the records 
are imperfect, the mild case of fever (Case 1) is of interest, since this may have been 
the 'infecting case' for the husband (Case 3), with a twenty-day incubatory interval. 
The connexion between cases 1 and 2 probably must go back to the same source of 
infection. It is also of interest that, although the cases started in the chalets on the 
one side of ours and then appeared on the chalets on the other side, we ourselves did 
not become infected. It may be noted that we were generally away during the 
daytime, and therefore avoided the active time of the local S. fasciata, and at night 
were so efficiently protected by mosquito nets that we were hardly ever bitten at 
night by C.fatigans nor at dawn by S. fas data. 
Our own illness was so long after these cases that I do not think it can possibly 
have been directly derived from them. It happened that we projected altering out- 
abode to the neighbourhood of the yellow fever hospital, chiefly owing to the rains 
and the deficient means of transport to and from the Institute. However, on 
January 10, we learned that one of the nursing sisters was laid up with yellow fever 
(from which happily she recovered), and about a week previously another sister had 
been laid up with a slight attack of fever 'which could not be yellow fever because 
she was a Brazilian.' We consequently judged that the hospital should be considered 
an infected house, and that it would be better not to transfer to its neighbour- 
hood. 
On the 14th we performeci two autopsies (one on a yellow fever case and the 
other not) ; that day we remained to dine at the hospital, and returned to the Marco 
about 8.30 p.m., otherwise we had not been at the hospital after dark since December. 
Seeing that I was taken ill with a rigor and vomiting on the night of the 15th, I do 
not think it possible that we could have been infected owing to this exposure, for the 
incubation would have been very considerably less than forty-eight hours. Curiously 
enough, just four days before, I had been most of the day catching mosquitoes about 
the sewage outfall of the hospital ; but as my companion had never been near the 
place, and was almost certainly infected simultaneously with myself, the infection 
cannot have been due to some bite received there. Most probably we must have 
been infected whilst about the wards of the hospital, or whilst at lunch some days 
before; if this is the case, the infection must have been during the daytime, and 
therefore by S. fasciata. It remains to be said that my colleague was taken suddenly 
ill on the morning of the 1 6th of January, and unhappily he went rapidly down hill, 
and anuria setting in, carried him off upon the 20th, notwithstanding the constant 
care of the Governor, Dr. Paes de Carvalho, Dr. Pontes de Carvalho, and the 
assiduous ministrations of the nursing staff. 
