Polio Eradication by the year 2000.Afr J Health Sci 1996; 3(3):65AJ
In May l988, the Annual Meeting of the World Health Assembly (WHA) committed WHO to the exciting challenge of Global Eradication of Poliomyelitis by the year 2000. The World accepted this challenge based on a number of scientific factors that had already been witnessed and certain other basic epidemiological factors concerning the transmission of the wild polio virus: 1. Smallpox had been eradicated and the global machinery and commitment for repeating such a feat could still be mobilised on She same lines to tackle another global menace; 2. The Pan American Health Organisation (PAHO) had already by May 1985 committed the American region to polio eradication by the year 1990. Although many people were initially sceptical of this initiative, it was quickly realised and recorded that the programme mounted by PAHO was achieving a high level of success and the goal of eradication was achievable; 3. Epidemiological! transmission factors that are persuasive to science for mounting eradication initiatives include: a) The wild polio virus moves from man to man only and has no wild animal reservoir to maintain it. b) An infected individual either dies, is crippled or fully recovers and remains immune without retaining or carrying the virus for many years (no carrier state) c) Available vaccine, particularly the oral (OPV) is not only capable of inducing long standing immunity in an individual but can, by multiplying in the gut, exclude or interrupt the circulation of the wild strain. The basic concepts and strategies for polio eradication recommended by WHO and now adapted globally are quite simple: 1. For each national expanded programme on immunisation (EPI) to raise the primary polio coverage rate with OPV to beyond 80% as a routine in children under one year. Under such conditions of immunisation in every locality in every district and province, the incidence of paralytic polio is quickly reduced to very low levels. Most countries in the world have already achieved and exceeded this level of coverage. 2. For each country to conduct National Immunisation Days (NIDs) daring which 2 doses of OPV, one month apart, are administered to ALL children under 5 years of age irrespective of their previous vaccination status. This strategy boosts the immunity in (he children already vaccinated and catches those missed by routine services. The wild polio virus cannot live for long periods outside the human body, hence the NIDs effectively remove the wild polio virus from circulation. China was able to vaccinate over SO million children under 5ysars with OPV within two days. Currently the practice is for many neighbouring countries (even upto 15 at a time) to simultaneously operationalise their NIDs on 2 to 3 days. 3. For each country to establish and operate an extremely sensitive surveillance system capable of detecting any new case of acute flaccid paralysis (AFP), Since paralysis can be produced by other conditions, it is necessary to back up the field surveillance with a reliable laboratory service capable of isolating poliovirus from the stool samples of paralytic cases. An isolated poliovirus would then have to be typed as wild or vaccine type strain. The strategies described above have all beers activated in all countries of the world and the world is already1 witnessing a dramatic disappearance of new cases of AFF. The International Certification Commission on Polio Eradication has established formal criteria by which countries can be certified polio-free. A polio-free status has to be maintained for at least 3 years in the countries of a region for that region to be certified as having eradicated the wild poliovirus. Global eradication will have been achieved if and when all regions in the world have been certified. The world is, no doubt, most grateful to all those international organisations, such as the Rotary International, WHO, UNICEF, national governments of the developed world through! donor agencies such as J1CA, US AID, D ANID A, etc., for the enormous resources that have been mobilised to operationalise EPI programmes for polio eradication. This gratitude is also a tribute in the late Dr. Albert Sabin, the discoverer of the oral poliomyelitis vaccine, which has been the major biological tool making it possible to eradicate the wild type poliovirus.