VI. NOTES ON POINTS OBSERVED IN YELLOW FEVER 
A. Typical Bites 
One of the cases seen in Cuba called our attention to a lesion of the skin which 
in our notes we referred to as ' typical bites.' These are small rounded rather pur- 
plish petechia-like patches some two or three millimetres in diameter, surrounded by 
a pale zone which makes them the more prominent ; they are without local swelling. 
In Para we have heard them called 'petechiae,' but on pressure they can be almost com- 
pletely banished so that the chief part of the lesion is a vascular dilatation ; also on the 
post-mortem table they are represented by palish rather violet patches which are not 
very prominent. In distribution they are found on exposed parts especially 
wrists and ankles, but not infrequently occurring as high as the elbow and up the leg. 
We met with an occasional case in which they were distributed more generally over 
the body ; thus one case is noted as covered with ' typical bites ' — on ' face, forearms, 
shins, and ankles, also chest and abdomen and a few on back, thighs free.' We rather 
tended to think that the prognosis was grave in cases in which they were abundant ; 
this particular case recovered after a severe attack. It may be mentioned that the 
pauper in Para is often not very thoroughly clad, and at night perhaps any part of the 
frame may be exposed to the attacks of mosquitoes. In general the face escapes so 
far as very obvious lesions are concerned, but close inspection sometimes shews quite 
minute punctiform dot spots (it may be noted that at one autopsy the cervical lymphatic 
glands were examined and found to be deeply congested and haemorrhagic) also with 
a circumferential pallor. 
They do not occur always, probably in about a quarter of the cases (they are 
noted in twenty-three out of ninety-four cases). Besides this many patients are seen 
to have been freely bitten as evidenced by the lesions and complaints. 
There are several questions of interest concerning these 'typical bites ' ; in the 
first place they were only observed in yellow fever cases, so that it may be presumed 
that they have something to do with the fever. If they are lesions caused by gnat 
bites are they due to the bite of a particular kind of gnat ? As judged by the bites 
we received they are not caused either by S. fas data or C. fatigans. Are they due to 
the bite of an uninfected gnat, in a person suffering from yellow fever in whom the 
vascular dilation and haemorrhagic tendency are present ? The answer here is, I 
think, in the negative since the patients in the yellow fever hospital were abundantly 
bitten by the above kinds, but typical bites did not occur after admission as far as was 
observed ; judging by the fewness of the cases of infection derived at the hospital and 
the late stage of the disease at which the patients were often admitted, the gnats about 
the place were probably mostly uninfected. 
