8 
(6) I have likewise been unable (p. 20) to confirm the hypothesis that this disease 
is transmitted by ticks, for while there is a certain amount of circumstantial evidence 
against this arachnoid, one of the fundamental premises of the tick theory (namely, 
the piroplasmatic nature of the disease) is called into question; and, further, cases 
are known in which a history of tick bite has not been established (p. 22). 
(c) I am unable to see any valid arguments (p. 25) in support of the view that the 
burrowing squirrel {CiteUus columhianus) forms the original host for the disease, 
while I find several arguments against this hypothesis. 
Having failed to confirm the piroplasmatic nature of Eocky Mountain “spotted 
fever” by direct evidence, I attempt to do so by indirect evidence, namely, by compar- 
ing the symptoms reported for this disease with those reported for known j^iroplas- 
matic maladies; but in this also my work is negative, for while a thin, watery, anemic 
condition of the blood, a thick condition of the bile, marked emaciation, prominence 
of hemoglobinuria, practical absence of skin lesions, and the occurrence of the cases 
in groups (corresponding to the extreme fertility of ticks) are the striking features 
described for piroplasmosis in animals, “spotted fever” patients present a thickened 
blood, fluid bile, no marked emaciation (at least so far as reported), little or no 
hemoglobinuria (Wilson and Chowning), prominent skin lesions, and the occurrence 
of isolated cases, widely separated. Accordingly, if this disease is a piroplasmosis, 
Piroplasma has an effect in man markedly different from the effect it has in cattle, 
sheep, dogs, and horses. 
Rocky Mountain “ spotted fever ” is reported for Idaho, Montana, Nevada, Oregon, 
Wyoming, ?Washington State, and possibly Utah and Alaska (p. 25). About 200 
cases are said to have occurred in the Bitter Root Valley since 1872 (p. 29) ; of these, 
139 have been collated, showing a lethality of 70.5 per cent. It is rather striking 
that the cases seem to be more or less confined to valleys (p. 30) , and infection seems 
to take place chiefly in the foothills. In the Bitter Root Valley the cases occur 
chiefly on the west side of the river, and are confined to the months of (January) 
March to September, inclusive; April, May, and June are the worst months. It is 
rather striking that more cases seem to develop under moist conditions (p. 33), as 
on the west side of the river, and during or following a rise in the streams caused 
by rain or melting snow, than under dry conditions; but the significance of this 
popular view is not altogether clear. Both sexes and all ages (p. 37) are subject to' 
the disease, but it is more common in males from 21 to 40, and in females from 11 to 
40 years of age, than at other times of life; the lethality varies, being in the Bitter 
Root Valley 45.4 per cent for females from 11 to 20 years of age up to 100 per cent for 
all patients over 60 years old. So far as one can judge, occupation (p. 38) seems to 
play a role, for a very large percentage of the patients are on farms or are connected 
with the lumbering industry. 
In Idaho, a mild type (p. 39) of the disease exists, with a lethality of about 1 to 3 
percent. In Montana, physicians speak of a mild type (without spots), medium 
cases, and severe, very fatal cases; some men also speak of cases of “localised” 
spotted fever (p. 39). 
About 90 per cent of the cases give a history of exposure to wet or cold (p. 39). 
The period of incubation (p. 40) is variously given as 2 to 21 days. The attack may 
be preceded by a few days of malaise, or the onset (p. 41) may be marked by sudden 
chill, followed by fever, with or without nausea; the disease usually lasts about 10 to 
21 days (p. 42); usually only one case occurs in a family (p. 43), but instances are 
known in which two members of a family are attacked the same day, or within a few 
days of each other; it is almost universally admitted (p. 44) that the disease is not 
contagious, but cases are known where contagion does not seem to be entirely 
excluded. 
The patients may assume a position of general flexion in bed (p. 45), and may have 
a peculiar urinous odor (p. 45) about them. 
