Indian J Pediatr 1988 ; 55 : 251-255

Strategies to control poliomyelitis in India Meharban Singh

Department of Pediatrics, All lndia Institute of Medical Sciences, New Delhi

Acute poliomyelitis is still endemic in several developing countries despite the availability of safe and potent vaccines for the past 25 to 30 years. Nevertheless, about 35~o of the countries have con- trolled it by widespread vaccination with either OPV (oral polio vaccine) or IPV (inactivated or intramuscular polio vaccine). I It is noteworthy that several countries in the tropics such as Singapore, Hong Kong and Cuba have also effectively controlled poliomyelitis thus demonstrat- ing conclusively that conventional vac- cines are effective in different hosts and environments. 2 The disease has not yet been completely eradicated from any region because imported and OPV- related paralytic cases are still being reported. 3

National scene

Based on several surveys of lameness and limited surveillance, the incidence of acute poliomyelitis in India has been calculated to be 20 to 40 per 100,000 population per year.4, 5 There are over 1.6 million polio victims in the country and about 200,000 new cases are added

Reprint requests : Dr. Meharban Singh, Professor of Pediatrics, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar New Delhi 110 029.

every year (500 polio victims/day). It is a sad fact that in rural India one in every 150 to 200 surviving neonates are destined to develop polio unless urgent preventive measures are taken. 6 There is ev;dence to suggest that incidence of polio is actually increasing in India despite National Immunisation Programme. 5 Apart from case fatality risk of about 5Yo, polio- myelitis is associated with sequelae of marked physical disability which poses considerable economic drain to our meagre resources by virtue of money and efforts being spent on their rehabilitation and reduced earning capacity of the victims. It is estimated that the annual cost of effective emergency and rehabilitation treatment of all patients of polio in the country works out to approximately 416 million rupees. 7 Acute poliomyelitis is thus a major public health problem and efforts should be made to eradicate it or at least control it.

Polio vaccines

There is conclusive evidence that both trivalent live polio virus vaccine ad- ministered orally (OPV) and inactivated polio virus vaccine administered intra- muscularly (IPV) are effective agents for preventing poliomyelitis. OPV has the advantages of easy administration by non- professionals, provides herd immunity

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by spreading to others through fecal-oral route, gives double protection by provid- ing both gut and humoral immunity and is relatively cheap. The major handicaps of OPV are relatively lower seroconver- sion rates and stringent 1iced for cold chain requirements for storage of vaccine in the health centre during transport and at the time of administration. The failure of OPV to protect against polio has been documented to the extent of 5 tc~ 2070 .4 The seroconversion rate of less than 7570 (as compared to 9970 in ~he USA) follow- ing three doses of OPV is explained on the basis of interference by a host of entero- viruses prevalent in a tropical country, neutralization bybreast milk and doubtful potency of OPV due to inadequate storage facilities. Despite attenuation, the residual neurovirulence of OPV is rather high as evidenced by occurrence of vaccine-virus induced poliomyelitis in susceptible adults the USA and other countries.

The inactivated polio vaccine is more potent, provides satisfactory protection even in the absence of gut immunity and is free from the risk of vaccine-associated poliomyelitis. It also needs professional assistance for administration and is considerably more expensive. It is the vaccine of choice for administration to children with primary and acquired im- munodeficiency disorders. The Salk vaccine (IPV) is routinely used in Sweden and is being actively considered for use in the USA because of its safety against vaccine-virus induced poliomyelitis. A single dose (maximum 2 doses) of frilled polio vaccine containing 40, 8 and 32 D- antigen units of type 1, 2 and 3 respecti- vely administered to six months old infants have been found effective in conferring prolonged immunity in over 90~o of sub- jects. 1

A potent and safe quadruple vaccine (incorporating IPV with DPT) is available and is likely to simplify the vaccination schedule in future. It is proposed that a 2 dose schedule of giving DPTP-BCG at three months followed by DPTP-measles at nine months of age may be enough to provide protection against 6-target diseases. Efforts are being made to produce a cheap, effective and stable polio vaccine on a mass scale by recombinant DNA and monoclonal antibody technology. 2 It is obvious that we do have the cost-effective tools to control polio, but what we need is the administrative skills and logistics to ensure delivery of the vaccine to 100 million under-five children in the country.

National polio vaccination policy

The WHO Expanded Programme on Immunization has its lofty goal ofimmuni- sing all children of the world by 1990 against 6-target diseases i.e. polio, diph- theria, tetanus, whooping cough, measles and tuberculosis. The polio vaccination has been available in India since 1965 but it was included in the National Immuni- sation Programme in 1979. Trivalent OPV is recommended along with three primary doses of DPT at intervals of four to six weeks followed by boosters at 18 months and school entry. Till 1980, mere 5 ~0 of urban children below two years of age had received 3 doses of OPV. The polio vaccine coverage achieved by the end of 1985 is estimated to be around 20 to 25~ (against the target of 45~o). The immuni- ration targets or goals set by the EPI- India are shown in Table. Polio immuni- zation has reduced the outbreak of acute poliomyelitis in the country but nc impact has been made on the incidence of the disease. The Government of India launched

SINGH : CONTROL OF POLIOMYELITIS 253

the 'universal immunisation' strategy on November 19, 1985 to immunize 85% of infants below one year of age by 1990.

Strategies to control poliomyelitis

There is an urgent need for a nationa} policy for the control of poliomyelitis because it continues to be a major public health problem. The trivalent OPV is successful in controlling polio because it is cheap, effective and provides protection to unvaccinated members of the com- munity through fecal-oral route. More- over, use of OPV has virtually eradicated polio in several developed and some developing tropical countries. There is need for indigenous production of enough OP'V to ensure delivery of a potent vaccine (properly stored) to all the under-five (at least under two years old) children through- out the country. The target should be to reduce the incidence of polio by 99% to bring it down to 0.15 to 0.30 per 100,000 population. 6

General sanitation and health education

There is intensive circulation of polio- virus in India due to prolonged fecal excretion by patients, inadequate sani-

tation and sewage facilities and lack of safe drinking water. The improvement in general socio-economic status, gross national product, environmental sanitation, literacy and health education and avail- ability of safe drinking water are likely to reduce incidence of several viral and bacterial water-borne infections which are spread through fecal-oral route. Health education, especially to women, is crucial for improvement of nutritional status and reduction of infections in children. The need and awareness for vaccinations can be created through the effective use of mass media. There is no denying the fact that general improve- ment in the environment is associated with reduction in the incidence of several infectious diseases but it may not have any impact on the incidence of acute poliomyelitis which may even paradoci- caIly increase during early stages, s During pre-immunisation era in developed coun- tries, it was observed that improvement in the living standards led to increased inci- dence or out-break of poliomyelitis. The reduction in the circulation of polio virus leads to increased population of suscepti, ble children and adults who escaped natural infection during early infancy. The improvement in the environmental

Table. National immunization goals

Target coverage (~ infants < 2 yr*) in the indicated year

Vaccine 1980 1985 1990 I995 2000

OPV 5 45 70 85 85 DPT 25 70 85 85 85 BCG 65 70 80 85 85

*There are about 20 million infants and 100 million under-five children.

254 THE INDIAN JOURNAL OF PEDIATRICS Vol. 55, No. 2

sanitation, however, may increase the 'take rate' of OPV by reducing the incidence of other enteric agents which are known to interfere with the vaccine. Several reports have documented that history of intramuscular injection into the limb prior to the onset of paralysis is available in 40 to 5570 of children with residual paralysis due to serologically and viro- logically confirmed poliomyelitis. 8 It is well known that for each case of paralytic poliomyelitis, there are at least 100 to I000 non-paralytic cases which may become overt following intramuscular injection which is often demanded by parents or given by physicians for the treatment of any nonspecific fever. There is need for a widespread campaign by the Indian Academy of Pediatrics to dis- courage use of injections by general practitioners and pediatricians. In tact the need for an intramuscular injection is extremely rare in ambulatory pediatrics (except for giving vaccination which are either intradermal or subcutaneous).

Schedule-oriented immunization programme

The EPI as a package to provide integrated primary health care to prevent common childhood diseases should be strengthened to improve coverage, The problems of availability of OPV and cold chain facilities for its storage must be diligently solved. Efforts should be made to provide coverage to almost 10070 of susceptible population through improved delivery system, logistics, community participation and dedication of health workers.l, 9 In view of extremely high circulation of polio virus in the com- munity at least 9070 coverage by 3 doses of OPV is likely to control the disease process. In urban Delhi and Greater

Bombay, the rates of three dose OPV coverage have reached 50 to 6070 but the incidence of polio ccntinues to be 14 to 24 per l00,000 population. 6 It is, there- fore, desirable to use additional vaccination strategies to control poliomyelitis during the next 5 to 10 years.

Sporadic targeted campaigns

The conventional schedule-oriented EPI programme should continue with renewed vigour but there is need to have sporadic polio immunization drives in a community or region to vaccinate all the children below five years irrespective of their previous immunization status. It has been shown that by the use of this 'cluster' or 'pulsed' approach in Vellore, the incidence of polio was reduced by 9070 within three months) The vaccination campaigns in selected pockets and focal areas of population create drive and enthu- siam among voluntary health workers and generate awareness and demand for vaccines among public. The targeted cam- paigns would complement the integrated basic health services programme in achiev- ing the control of polio in a shorter time.

National mass polio vaccine campaigns

Several models have demonstrated that when there is a political will to eradicate a disease, it can generate enough funds and public support to achieve it. Cuba, Brazil and Mexico have demonstrated the utility of annual nationwide OPV mass polio vaccination campaigns for eradi- cation of poliomyelitis.2, 9 During the past several years they have organised annual vaccination drives to cover all under-five children to provide 2 doses of OPV two months apart i.e. two days, two months

SINGH : CONTROL OF POLIOMYELITIS 255

apart , designated as national polio vacci- nation days. The campaign was launched with much publicity and the support of a large number of volunteers. Our p rob lem is the number of susceptible children (approximately 100 million) and enormous size of the country. We need resources and of coarse enough of indigenously manufactured OPV, at least 250 million doses per year for annual campaigns alone. We have the necessary manpower and even a large number of voluntary work force can be mustered by a concerted drive. We do have the organisational capacity. I t is essential that 'pulse' or mass immtmization campaigns should have separate budgetary allocations and they should not use the meagre resources of integrated basic health services. There is need to identify our major public health problems, define national health priori- ties and launch a crusade against them on a war footing. I t is possible to eradi- cate or at least effectively control polio- myelitis because we have the scientific knowhow and effective tools but there is need for political will and monetary sanctions. 10

Epilogue

I t is feasible to effectively control poliomyelitis by ensuring universal im- munization of all under-five children with trivalent OPV delivered through the net work of existent M C H basic health posts. There ts a need for enhancedindi- genous mam:facture of enough OPV, maintenance of cold chain system for storage and strategies and logistics for the delivery of the vaccine to all children.

Targeted regional vaccination drives and annual national polio vaccine campaigns can achieve the goal in the near future. The mass availability of a mere potent but cheap single or two-dose ]PV, or a quadr0ple vaccine (DPTP) would be a welcome development. The OPV wotdd become still more acceptable if it could be made relatively more heat stable and safer by further attenuation of its neuro- virulence.

References

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2. Robbins FC, Nightingale EO. Selective pri- mary health care : Strategies for control of disease in the developing world IX. Polio- myelitis. Rev Infect Di~ 1983 : 5 : 957-968

3. Horstmann DM. Control of poliomyelitis, a continuing paradox. J Infect Dis 1982; 146 540-541

4. JohnTJ. Poliemyelitisin India : prospects and problems of control. Rev Infect Dis (Suppl 2) 1984; 6 : $438-$441

5. Prabakar N, Srilatha V, Mukerji D, et al. The epidemiology and prevention of polio- myelitis in a rural community in South India, Indian Pediatr 1981 ; 18 : 527-532

6. John TJ. How shall we control poliomyelitis in India 9. Indian J Pediatr 1981 ; 48 : 565-568

7. John TJ. Cost and benefits of immunization in India. Indian Pediatr 1981 ; 18 : 513-516

8. Maiya PP, Jadhav M, Mukundan P, et al. Paralytic poliomyelitis : Clinical and viro- logical observations. Further studies on 201 children, lndian Pediatr 1981 ; 18 : 533-537

9. Chen J. Can paralytic poliomyelitis be eli- minated ?Rev Infect Dis (Suppl 2) 1984; 6 : $581-$585 Evans AS. Criteria for assessing accomplish- ment of poliomyelitis control. Roy Infect Dis (Suppl 2) 1984; 6 : $571-$576

10.