Letters to the Editor

Indian Pediatrics 1999;36:519-521

Serological Profile of Cases of Acute Flaccid Paralysis

With the mass immunization initiative for eradication of poliomyelitis a significant decline in the number of cases of acute flaccid paralysis (AFP) has been observed(1). AFP cases however, can be both of polio or non- polio origin. There are several reports on clinico-epidemiological studies(2,3) on AFP, but serological investigation particularly the IgG response in such cases has not received adequate attention. These studies can be useful tools for AFP surveillance and may provide necessary feed back for the on going pulse polio immunization program. Therefore, an investigation on IgG response in cases of AFP has been undertaken.

Twelve cases of AFP admitted in the children medical ward, Kamla Raja Hospital, G.R. Medical College, Gwalior during one year study period (September 1996 to August 97) were studied. The youngest case was 4 months old while oldest was 3 years; maximum cases were in the 13-24 months age groups. The patient's history including history of OPV immunization, number of doses, age at the time of administration, source/agency for the vaccination, time of administration were recorded. Blood was collected in each case. The IgG antibody titer was determined by the Indirect ELISA method according to the standard procedure.

The clinical profile of cases showed that cases of spinal type without bulbar involvement were more common (83.8%) in comparison to bulbo-spinal cases (16.2%). These observations are similar to those of Ratnaswamy et al.(2) in which 80% spinal type, 17.5% bulbo-spinal and 2.5% with encephalitic manifestation were reported. The only mortality observed was of the case with bulbo-spinal presentation.

For serological investigations first antibody cut-off titer vis-a-vis high titred positive sera was determined by taking a mean value from 27 OPV unimmunized and non-AFP cases, and was found to be ≤1 :20. This titer was considered insignificant decided by the fact that majority of cases among unimmunized children showed antibody titer ≤1:20. On the other hand, the significant antibody titer observed ranged from low antibody titer of 1 :40 and 1 :80 to medium titer 1: 160 and 1 :320, and high titer of 1 :640 and ≥ 1: 1280. The insignificant and low antibody titre has been taken as poor antibody response in the present discussion.

The AFP cases of the present study were then investigated and the results are listed in Table I. Out of 12 cases 2 were seronegative against all three poliovirus types. Seven cases were seropositive against one poliovirus type (PIIP2 or P3); however, the antibody titre was poor in all cases except one. These cases did not show any marked recovery during the period of observation. Three cases with previous 5 doses OPV immunization were seropositive against 2 viruses (PI/or P3) with high IgG antibody titre and showed a marked recovery within 60 days of observation. None of the AFP cases was found to be seropositive against all three polioviruses.

TABLE I
 IgG Response in Cases of AFP

* Expired within 24 hours of admission

Amongst the cases studied 3 were unimmunized, while others received 1 to 5 doses of OPV. As reported earlier(4) a significant difference in the incidence of poliomyelitis in immunized and unimmunized was noted, being more amongst the unimmunized children. The picture has changed now following pulse polio immunization and there were 9 cases of AFP among children with some immunization in our study. Sharma(3) found that acute disease among fully vaccinated population has shown a steady rise from 1.9.% to 13.9%. Such an increase in the incidence of polio in vaccinated children raises questions about facilities for maintenance of cold chain, factors interfering with development of immunity or other non-polio bntero viruses for polio like illness which are responsible for such a crippling disease.

Findings from present study suggests that despite some immunization several cases had poor antibody response. This might be because of interference in the uptake of vaccine virus by non-polio viruses. On the other hand high IgG antibody titre observed in 3 cases of AFP with previous 5 doses of OPV immunization who showed marked recovery within 60 days "excludes the possibility of paralytic poliomyelitis being the cause. A good antibody response along with marked recovery points towards the possibility of non-enterovirus as being the cause which can produce al- most similar polio like illness.

The isolation and identification of en-terovirus are time consuming and involve intricate procedures. On the other hand ELISA methods are simple and easy to handle. From our observation, it may be concluded that detection of enterovirus specific IgG can be an useful method which can help to detect the etiology of paralytic attacks within short period of time, and is also easy to perform. At the same time one can not underestimate the role of non polio virus (CY A 7 and eYB3) in paralytic polio like illness(5). Even though the number of cases of AFP investigated are small, nevertheless the observations are useful for further studies to be taken up in this direction.
 

S. Jaiswal,
A.M. Jana*,
Y.P. Thawrani,
K.M. Belapurker,
Department of Pediatrics,
G.R. Medical College and Virology Division,
Defence R & DEstablishment,
Gwalior 474002, India.