178 
MALARIA 
TABLE XIII 
P. vivax: Relation of Peeiod of Renewed Activity to Peeiod of Inoculation 
(Boyd and Kitchen 1937d) 
Period of 
inoculation 
Period of renewal 
Quiescent 8-24 weeks 
Quiescent more than 24 weeks 
Winter Spring Summer Fall Total 
Winter Spring Summer Fall Total 
Winter . 
Spring . 
Summer . 
FaU . 
Total . 
1 ... 1 
2 4 6 
1 1 
2 1 ... ... 3 
2 1 3 5 11 
2 1 ... ... 3 
4 ... ... 4 
1 2 2 ... 5 
3 7 2 0 12 
Another feature of interest in relation 
to these long term recurrences is shown in 
Table XII. 
It is to be noted that we have not ob¬ 
served long term recurrences subsequent to 
artificial inoculation. It may be mentioned 
that neither Yorke and Macfie (1924a) nor 
James (1931) have observed renewed ac¬ 
tivity following the termination of at¬ 
tacks induced by artificial inoculation 
after periods of quiescence of more than 
8 weeks duration. 
The season in which renewed activity 
after a long quiescence has occurred is com¬ 
pared with the season of inoculation in 
Table XIII. 
It is thus seen that renewed activity has, 
in our experience, less frequently followed 
inoculations made in the winter months 
than those made at other seasons. It is 
interesting to observe that most secondary 
attacks after the longest intervals of quies¬ 
cence have occurred in the winter or spring. 
The longest interval we have observed be¬ 
tween the termination of a primary vivax 
attack and a secondary attack has been 394 
days. 
These long term recurrences present 
another feature of interest as may be seen 
from Table XIV. If we assume that re¬ 
newed activity within 8 weeks of the termi¬ 
nation of the primary attack may be re¬ 
garded as essentially a part of the latter, 
and group our cases accordingly, it will 
then be noted that either the primary attack 
or an early secondary attack had been in¬ 
terrupted in all patients who experienced 
clinical activity 24 weeks after the termi¬ 
nation of the primary attack, and that 
interference had also been practiced in the 
TABLE XIV 
Showing the Manner in Which the Peimaey Attack and Eaely Secondaey Attacks Weee Ter¬ 
minated, in Certain Cases of Vivax Malaria who Subsequently Experienced 
Long Term Recurrences 
Termination 
of primary 
attack 
Duration of 
original at¬ 
tack (days) 
Recrudescence 
0-7 weeks: 
termination 
Persons 
with re¬ 
lapse in 
8-24 
weeks 
Previous 
recrudescence 
0-7 weeks; 
termination 
Previous re¬ 
lapse 8-24 
weeks; termi¬ 
nation 
Recur¬ 
rences 
after 24 
weeks 
Spont. Induced 
Spont. Induced 
Spont. Induced 
7-20 
2 
2 
... 
... 
Spontaneous 
21-41 
1 
2 
2 
... 
2 
Over 42 
1 
. 
7-20 
1 
2 
2 
1 
6 
Induced 
21-41 
1 2 
3 
1 
4 
Over 42 
. 
1 
. 
