Indian Pediatrics - Editorial

Letters to the Editor

Indian Pediatrics 2000;37: 913-916

Polio Eradication Strategy: Need for Re-appraisal

Polio eradication program is a national project, and poliomyelitis being a disease of childhood, Indian Academy of Pediatrics is rightly concerned about the success of the polio eradication project.

Before launching 6 doses scehdule Intensified Pulse Polio Immunization in Rajasthan for years 1999-2000, a workshop was held in Jaipur. We were provided AFP Surveillance reports for the period of first 30 weeks ending on 31st July 1999 along with other documents. According to the surveillance report there were 56 confirmed cases of paralytic poliomyelitis in Rajasthan upto 31st July 1999. Wild polio virus was detected in the stool samples of 5 children, thus five cases were ‘virologically confirmed’ and 51 were ‘clinically confirmed’ or ‘compatible with polio’ cases. Although this report for 30 weeks presents data for 56 confirmed cases only, there are some observations which merit attention.

1. Polio Case

From collection of the stool samples to transportation to the assigned laboratory, many factors can reduce the chances of virus detection in the stool. Stool samples were collected in 27 children, one sample each in three children and two samples each in 24 children; thus there were 51 stool samples collected. Polio virus was detected in stool samples of seven children; vaccine virus in two children (in 3 out of 4 samples) and wild virus in 5 children (in 9 out of 47 samples). Interval between collection of the sample and delivery to the laboratory varied from one day to fifteen days.

Some suggest that AFP case with wild polio virus detected in stool should only be considered as a confirmed case of poliomyelitis and not a case ‘compatible with polio’, we may miss many cases of poliomyelitis because of poor detection rate. If we apply this criterion then we are already very close to polio eradication, because in 1999 there were only 1126 cases in whole country where wild polio virus was detected in the stools of AFP cases, as on 15th April 2000.

2. OPV Administered After Onset of Flaccid Paralysis

Polio vaccine is recommended after an attack of paralytic polio to prevent the disease by other serotypes of polio virus, because there is no cross immunity. It is recommended after 4-8 weeks of the onset of polio. Four children had been administered OPV after a very short interval after onset of paralysis and two children received polio dose on the day of onset of paralysis. This can result in spurious vaccine virus detection in the stool samples of AFP cases. The details are given in Table I. Out of these six children, five had received OPV on NIDs (17th January and 14th March 1999). Children at serial numbers 5 and 6 had been administered 7th and 12th doses, respectively and both children expired.

Table I - Children Administered OPV on Same Day or After Onset of Paralysis

No.	ID code	Age in months	Doses received	Date of
No.	ID code	Age in months	Doses received	Onset of polio	OPV
1	RJDGP99003	60	3	7-5-99	22-5-99
2	RJBTP99003	72	7	27-2-99	14-3-99
3	RJGGN99001	16	4	25-2-99	14-3-99
4	RJJLR99001	12	5	12-3-99	14-3-99
5	RJBTP99001	26	7	17-1-99	17-1-99
6	RJKTA99004	60	12	14-3-99	14-3-99

3. Vaccine Associated Paralytic Poliomyelitis (VAPP)

Although the exact number of cases of VAPP is not known, but consensus is that the number of VAPP cases is much higher than the expected 60-75 cases per year for our country. According to the documents which were provided to us during the Workshop on ‘Polio Eradication’ held in New Delhi on 20th and 21st May 2000 there were 508 samples of stools from AFP cases during 1999 where vaccine virus was detected. Some cases could be spurious (as explained earlier, some children are administered OPV after attack of paralysis but before collection of the stool sample). Number of VAPP cases could be high in our country due to the following reasons:

(a) Vaccine virus becomes virulent: In such an event the number of VAPP cases would have been in thousands or lakhs and would have occured in clusters.

(b) Inherent host factors: Some unknown host factor(s) may make our children more prone to VAPP, again the number of such children would have been in thousands or lakhs.

(c) Immunocompromised children: It is known that risk of VAPP is 2000 times higher in immunocompromised children. The number of VAPP cases could be high because OPV is administered to all the target children with the message that OPV is absolutely safe vaccine and should be administered even to a sick child. Specific vaccines are available in our country for certain high risk population, viz., Pneumo-coccal vaccine, Influenza vaccine, but IPV is not available for immunocompromised children. On 9th June 2000 I had written to Dr. Sobhan Sarkar, Assistant Commis-sioner, Immunization, Ministry of Health and Family Welfare, New Delhi, with a copy to Dr. G.S. Hathi, Hon. Secretary General, Indian Academy of Pediatrics, Mumbai, stating that IPV be made avail-able for high risk population on payment like other vaccines.

In year 2000 upto 15th April, the number of polio virus detected in stool samples of AFP cases was–wild polio virus in 51 cases and vaccine polio virus in 121 cases.

4. Pulse Polio Immunization

The report has mentioned date of last dose of OPV given for 32 children. Thirty children had received last OPV dose on PPI days (Table II).

As the report is for AFP cases from 1st January to 31st July 1999, there may be some more cases of paralytic polio following 6th December 1998 round, which occurred before 31st December 1998. The rise in number of polio cases between 17th January 1999 (n = 8) and 14th March 1999 (n = 19) polio administration is very high which can not be due to 250% increase in the number of vaccinees in Rajasthan for the 14th March round of PPI.

Table II - Children who Developed Polio After Receiving OPV on PPI Days

Date of last dose of OPV	Number of children who developed polio
6th December 1998	3
17th January 1999	8
14th March 1999	19

Table III - Number of Doses Administered

Number of
children
3
1
2
1
1
1
5

5. Vaccine Failure

The number of doses received by each child is given in Table III. Out of 56 children mentioned in the report, 11 children had not received any dose of polio vaccine (un-vaccinated), 27 children had received 1 to 4 doses of vaccine (partially vaccinated) and 18 children had received 5 or more doses of vaccine (fully or over vaccinated).

Eighteen children (32%) had received 5 or more doses, i.e., these children were fully vaccinated, but un-immunized even after taking high number of vaccine doses. The child who had received 13 doses of OPV and developed paralytic polio was 4 years old at the time of illness and had received the 13th dose when she was less than 3 years and 9 months. She received the 13th dose on 17th January 1999 and developed paralytic polio on 22nd April 1999. Out of the eight fatal cases of polio in this report, one child had 12th dose on the day of illness.

In case, three doses of vaccine are considered adequate for individual protection, then 36 children (64%) had received adequate or more doses of vaccine and still developed paralytic polio.

Table IV - Children with Poliomyelitis who Expired

Duration of
Illness in days
2
6
20
2
3
8
4
7

6. Fatal Polio

Eight children expired. Four children had not received any dose of polio vaccine, other four children had received one each 5, 7, 8 and 12 doses. The age, number of OPV doses received and duration of illness are presented in Table IV.

Although, cause of death in these eight children is not mentioned; in addition to aspiration or infection, death in poliomyelitis occurs in children who have bulbar and/or encephalitic involvement. In this report the ratio of non-fatal cases and fatal cases (48 : 8) is similar to that reported earlier(1) [80% spinal type, 17.5% bulbospinal and 2.5% with encephalitic manifestation], so probably these were cases who had bulbar and/or encephalitic involvement.

7. Age for Vaccination

Seventeen children were above 5 years of age, i.e., 30% were above 5 years of age at the time of onset of the disesae. In view of this observation, we should consider raising the upper age for polio vaccine administration from 5 years to 12 years or so to provide protection to the children beyond five years of age who may be vulnerable to polio virus.

Paralytic polio including fatal polio occurring in children who had received large number of OPV doses should be a reason for serious concern regarding the efficacy of OPV including the improved vaccine with enhanced P3. In addition, there will always be a risk of VAPP.

Yash Paul,
A-D-7, Devi Marg,
Bani Park,
Jaipur 302 016, India.

Reference

Ratnaswami L, John TJ, Jadhav M. Paralytic poliomyelitis in South Indian children - Clinical and virological observations. Indian Pediatr 1973; 10: 443-447.