192 
MALARIA 
DAT OF DISEASE 
Fig. 3. No. B-2813 (P. malariae): Upper panel shows a double quartan course becoming quotidian. 
Two cycles disappear resulting in a simple quartan course. Lower panel shows postponement of one 
cycle and its final merger with another cycle. 
teristic of our artificially induced infec¬ 
tions. Thayer and Hewetson (1895) and 
Craig (1909) appeared not to have seen as 
many instances of multiple cycles as has 
been our experience. It ought to be pointed 
out that these authors were dealing wholly 
with naturally inoculated patients. As we 
shall mention later, our naturally induced 
infections were also of a simple pattern. 
Boyd (1940b) further observed that in the 
case of paroxysms prior to remissions of 
over 8 days in artificially inoculated 
patients, most of the quotidian paroxysms 
occurred in the patients who experienced 
primary attacks of less than 73 days’ dura¬ 
tion; and where the attacks lasted over 
144 days they chiefly consisted of simple 
quartan paroxysms and no quotidian ex¬ 
perience was evident. On the other hand, 
in the case of naturally inoculated patients, 
with pre-remission attacks of less than 73 
days duration, none exhibited quotidian 
paroxysms though these were noted in a 
few attacks of longest duration. 
In comparing the parasite densities at 
the onset of paroxysms in 23 artificially 
induced quartan infections, with the lapse 
of time between first appearance of para¬ 
sites and first paroxysms, there was noted 
a significant positive correlation (Table I). 
As Boyd (1940b) observed, the tolerance for 
these parasites is surprising in view of the 
scarcity of quartan malaria in this country. 
TABLE I 
Coeeelation between Tolerance FOR P. malariae 
and Interval from First Detected 
Parasites to First Paroxysm 
Days elapsing between first 
Parasite 
detection of parasites and 
density per 
clinical onset. Number 
cmm sit 
of patients 
clinical onset 
0-7 
8-14 
10-500 
15 
1 
500 + 
1 
6 
X2 = 15.38 P <T 0.01 
