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Indian Journal of Community Medicine

Vaccine Polioviruses In Stool Samples of AFP Cases

Author(s): Yash Paul

Vol. 31, No. 3 (2006-07 - 2006-09)

Vaccine polioviruses contained in OPV replicate and multiply in the gut of vaccine recipient, may produce antibodies against one or two serotypes at a time, thus inducing immunity. During this process some polioviruses may mutate and become neurovirulent, capable of causing vaccine associated paralytic poliomyelitis (VAPP). The vaccinee may continue to shed, both attenuated vaccine polioviruses as well mutant neurovirulent vaccine polioviruses in feces for 4-6 weeks. The immunocompromised vaccinees may continue virus shedding for a prolonged period.

A case of acute flaccid paralysis (AFP) who had fever at the time of onset of asymmetric paralysis, the residual paresis persists beyond 60 days of onset, and vaccine polioviruses had been detected in the stool samples, but, OPV had not been administered less than 4 days before or after onset of paralysis is called VAPP case. If OPV had been taken 4-40 days before onset of paralysis, it is called a recipient VAPP case1,2. In case OPV had been taken more than 40 days before onset of paralysis, then it is called a contact VAPP case, because, mutant vaccine polioviruses had reached the child through secondary spread of viruses shed by some vaccine recipient.

Presently all the AFP cases where vaccine polioviruses are detected in stool samples are discarded as non-polio cases by the National Polio Surveillance Project (NPSP). Because of this policy many polio cases are being missed on two counts: (1) vaccine associated paralytic polio cases are being discarded as non polio cases, and (2) compatible polio cases are being missed in case OPV had been administered after onset of paralysis or less than four days before onset of paralysis i.e. during the incubation period, but, before collection of stool samples. Some representative AFP cases are being presented in Table 1.

Case number 1 had residual paralysis on 31 st July i.e. well beyond 60 days follow up. The child had received OPV more than 40 days before onset of paralysis, so this was a contact VAPP case but had been discarded as non-polio because vaccine polioviruses had been detected in stool sample. Case number 2 had residual paralysis on 23rd May i.e. after 80 days of onset of paralysis. Because vaccine polioviruses had been found in the stool sample, this case was discarded as non-polio with a final diagnosis of GBS, although the common presentation of GBS is symmetrical paralysis without fever at onset of paralysis. Case number 3 also had similar presentation and had been labeled as GBS, and not a recipient VAPP case.

Case number 4 had been discarded as non-polio case because vaccine polioviruses had been found in both stool samples. This was a compatible polio case. No date of OPV administration for case number 5 was mentioned, but had been discarded as non-polio because vaccine polioviruses had been found in stool sample, although had residual paralysis after 9 weeks of onset of paralysis. It was a case of VAPP, either recipent or contact, depending on whether OPV had been administered 4-40 days before onset of paralysis, or earlier. Case number 6 had been administered OPV one week after onset of paralysis, but discarded as non-polio because vaccine polioviruses had been detected in stool samples. This should have been labeled as compatible polio case because wild poliovirus had not been detected in stool samples.

Cases at numbers 7 and 8 did not fulfil the criteria to be labeled as polio, because fever at onset of paralysis and asymmetric paralysis both were absent, and there was no residual paralysis on followup. One child had been administered OPV after onset of paralysis and other one expected to be found in the stool samples, and had been rightly discarded as non-polio cases.

Thus every AFP case where vaccine polioviruses are found in stool samples should be scrutinized for being a case of polio, either caused by vaccine or a compatible polio case where OPV had been administered shortly before collection of stool samples.

The AFP line lists for Rajasthan were prepared and provided by NPSP.

S.
No.
Epid Number Date of
Onset of
Paralysis
Date of
last OPV
Dose
Fever on
day of
Paralysis
Onset
Asym-
metrical
Paralysis
Date of
Followup
Followup
Result
Final
Clas-
sification
Final
Diag-
nosis
1 MRPTM01003 22.05.01 21.01.01 Present Present 31.07.01 RP Dis
2 RJPL101002 04.02.01 21.01.01 Present Present 23.05.01 RP Dis GBS
3 RJJDP02002 25.01.02 20.01.02 Present Present 22.04.02 RP Dis GBS
4 RJCRU00003 27.02.00 27.02.00 Present Present 06.04.00 Exp Dis
5 RJPL100005 09.04.00 Present Present 15.06.00 RP Dis
6 RJSAW00004 19.03.00 26.03.00 Present Present 25.05.00 Exp Dis
7 RJJPR01006 14.01.01 21.01.01 Absent Absent 14.03.01 NRP Dis GBS
8 RJDSA01009 05.12.01 04.12.01 Absent Absent 10.02.02 NRP Dis

RP – residual paralysis, NRP – no residual paralysis, Exp – expired, Dis – Discarded

References

  1. Kohler KA, Banerjee K, Hlady WG, Andrus JK, Sutter RW. Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine. Bull WHO 2002; 80: 210 – 216.
  2. Andrus JK, Strebel PM, de Quadros CA, Olive JM. Risk of vaccine-associated paralytic poliomyelitis in Latin America, 1989-91. Bull WHO 1995; 73: 33 – 40.

Yash Paul
Consultant Pediatrician,
A-D-7, Devi Marg,Bani Park,
Jaipur-302 016, India.
E-mail: [email protected]

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