LIVE POLIO IRUS VACCINES

Epidemiological, Virological Survey Following Oral Administration 139
w >'
Oc.
u- uz
. v
L Z
u
LU Z
1 11 III IV V
97 152 143 499 384
I 11 III IV V II I III IV V REGION
108 86 170 524 272 95 40 103 260 129 NUMBER OF
INDIVIDUALS
EXAMINED
7
6
5
TYPE 1
TYPE 2
3
2-
TYPE 3
1957
FIG. 5.
1958 1959
Incidence of virologically confirmed poliovirus infections.
logs for highly virulent strains and more than
four logs for highly attenuated strains, so that,
in agreement with Yoshioka, Riordan, and Horstmann
4 , the strains were classified as:
T+: difference less than 2 logs.
I: difference 2 to 3.9 logs
T: difference 4 logs or more
Table 2A shows that all Type 1 strains excreted
by vaccinated individuals, with the exception
of one intermediate strain, possess the T
character. This character is correlated with absence
of neurovirulence following intracerebral
inoculation of amounts of virus varying from
105.7 to 10 s - 2 TCD,5, with the exception, however,