LIVE POLIO IRUS VACCINES

Vaccination with Attenuated Polioviruses in Costa Rica
571
screened by the conference panels, 59 were accepted
as paralytic poliomyelitis. Forty-five of
these occurred in non-vaccinated persons. Results
of virological studies on the 27 of the 45
from whom specimens were obtained are summarized
in Table 2. Poliovirus was isolated
from 15 of these stool samples. Type 2 poliovirus
was isolated from 12 patients, Type 3 from
two, and Type 1 from one. Non-polio enteroviruses
were isolated from four, no virus was
obtained from five stools, and the results in three
instances are pending. Of the 59 polio cases, 26
were in the metropolitan area and 13 of these
were in non-vaccinated individuals. The remaining
33 cases were scattered among all of the
seven provinces and 32 of them were in nonvaccinated
persons. It should be noted that two
of the cases in non-vaccinates, which were clinically
accepted as paralytic poliomyelitis, were
seronegative for all three types of poliovirus
and in one of these patients the serologic finding
was confirmed by a second blood specimen
obtained one month after the first.
The remaining 14 of the 59 confirmed paralytic
poliomyelitis cases occurred in individuals
who had received oral poliovirus vaccine. Thirteen
of the 14 cases were reported from the
metropolitan area and the other came from the
province of San José. The virological findings
in these cases are summarized in Table 2, where
it may be seen that six poliovirus isolates were
recovered. Types 2 and 3 were both recovered
from one patient, and four of the other five isolates
in cases were Type 2 poliovirus. Type 1
was not recovered. Non-polio enteroviruses
were isolated from two specimens and one
failed to yield any virus. Stool examinations
are incomplete in two instances.
Table 3 presents a summary of accumulated
data pertaining to the 14 paralytic cases which
had a history of oral poliovirus vaccination.
Stool and blood specimens were collected from
13 of them, and from one case serum only was
obtained. Up to this time, complete laboratory
results are available for seven of the 14 patients.
For three others, serologic findings are available,
and in two of these stool examinations are incomplete.
Of the remaining four recently reported
cases, neither stool nor blood specimens
have yet been examined.
With the exception of case No. 286 which will
be discussed separately, all of the patients received
oral poliovaccine more than seven weeks
before the onset of illness.
Case No. 53. Isolation of ECHO virus from
the fecal material obtained more than one
month after onset is not very significant for the
implication of this agent as the cause of the
illness; however, the isolation of ECHO virus
from four of its six household contacts gives
reason to entertain this possibility. The absence
of Type 2 antibodies more than a month
after the illness started shows clearly that the
symptoms were not caused by Type 2 virus,
either wild or of vaccine origin, although it does
indicate a lack of response to the Type 2 vaccine.
Type 1 vaccine was not fed to this patient
and the high titer of Type 1 antibodies suggests
the possibility that a Type 1 infection may have
been the cause of the disease.
Cases Nos. 269, 270, 277, and 283. Two of
the patients received the full course of oral vaccination
with monovalent strains, and one received
trivalent vaccine. The last one (283)
received only Type 2 vaccine. The lapse of time
between vaccination and onset exculpates the
vaccine as the cause of symptoms in all four of
these cases. The isolation of Type 2 poliovirus
from the fecal specimens of these cases plus
the presence of Type 2 specific antibodies in
their sera indicate a lack of response to the Type
2 vaccine. Also the serologic results of Cases
Nos. 270 and 277 indicate a lack of response to
Type 1 vaccine.
Case No. 228. No stools were collected. Serology
establishes Type 1 infection and lack of
response to Type 2 vaccine administered at six
months of age.
Case No. 282. The last monovalent vaccine
dose was administered five months before illness
occurred. No enteric viruses were found in the
stool collected nine days after onset. The serology
indicates the possibility of Type 1 infection
and consequently a Type 1 vaccine failure.
Case No. 286. This patient received trivalent
vaccine ten days before the onset of illness.
Preliminary examination of the stool collected
nine days after onset, indicated the presence of
Types 2 and 3 poliovirus. Also, the presence of
a Coxsackie virus is suggested by mouse inoculation
results. A serum taken on the same day
as the stool sample showed an antibody titer of
1:128 against Types 1 and 2, and a titer of 1:4
against Type 3. The stool examination is not