POST 01174E : ERADICATION EFFORTS

POST 01174E : ERADICATION EFFORTS 20 October 2007 ______________________________________________________ Robert Davis from UNICEF/ESARO proposes the following analysis of eradication efforts. Food for thought and discussion! ___________________________________________________________ Proof of concept for four eradication efforts: malaria, smallpox, polio, and measles MALARIA The 1955 decision by WHO's governing body to launch a worldwide war on malaria was made after stunning victories against malaria in the Balkans, southern Europe, and Taiwan. The proof of concept was so geographically narrow as not to demonstrate feasibility in countries and continents with different economic, political and environmental conditions. In particular, the colonial regimes of the 1950s were unwilling to make the massive outlays which could have advanced malaria eradication, along WHO guidelines, in subsaharan Africa. Also, the planners of 1955 underestimated the speed with which resistance to insecticides and antimalarials would compromise prospects of the global programme. No efforts were made to limit the use of DDT in agriculture, which may have speeded the development of insecticide resistance in malaria eradication. In 1969, after stagnation in most of Africa and setbacks in several large Asian programmes, the World Health Assembly passed a resolution saying that eradication was not possible except through primary health care. This was a tacit admission of defeat for what started as a vertical eradication programme. SMALLPOX The series of smallpox eradication resolutions, dating from the 1950s, was originally based on the assumption that mass vaccination campaigns were both necessary and sufficient to stop smallpox transmission. Many industrialized countries stopped smallpox transmission either by universal vaccination or by mass campaigns, or a combination of the two. It was only when, during Nigeria's civil war, surveillance and containment showed the feasibility of a more focal approach, that smallpox eradication became truly feasible. New emphasis on surveillance as a tool of focal containment produced dramatic results, first in Nigeria, then in other endemic countries. Finally, smallpox eradication was cheap. The total international outlays were on the order of $125 million, a mere fraction of the figures for other eradication programmes. A single organization, WHO, took the lead, with help from CDC, so there were few difficulties delineating tasks among partners. POLIO Industrialized countries eliminated polio through a combination of polio days and routine vaccination. Latin America showed that mass campaigns using trivalent oral polio vaccine could stop transmission even when routine coverage was suboptimal.. Over a period of years, the combination of routine vaccination and mass campaigns stopped transmission in the western hemisphere, then, less quickly, in Asia and Africa. When Type 2 wild poliovirus disappeared, the advantages of monovalent vaccines became evident. The post-2000 eradication efforts have brought several issues to the fore: the need to deal with circulating vaccine derived polio virus, the relative advantages of monovalent over trivalent vaccine for mass campaigns, and the need for faster outbreak response through new lab protocols with faster turnaround and immediate outbreak planning upon lab confirmation of wild poliovirus. Donor support continued, even during the period 2003-2006, when global cases stagnated between 1000 and 2000 per year. The current year has seen striking declines in incidence, both in the four endemic countries and in importation countries. MEASLES Because it is so contagious and travels so well, measles can only be tackled on a national and continental scale. This has been done successfully in the region of the Americas, but less so in the rest of the world. The successes of measles elimination in the western hemisphere have fueled both the global Measles Partnership, bringing together donors and other partners in a more coherent way than some previous efforts, and regional elimination resolutions in 4 out of 6 WHO regions. The future of measles elimination initiatives is largely a matter of funding. Will the international community opt for permanent control, or a "short, sharp shock" approach? There will be little enthusiasm for a two decade effort of the kind, now coming to a conclusion, against polio. THE AFRICA FACTOR In each of these four efforts, Africa has played a pivotal role. In the case of malaria, the then colonial governments ruling most of Africa failed to make the political and financial investments needed to launch malaria eradication along WHO guidelines. Ethiopia, always independent, was an exception, but even there the application of WHO guidelines did not bring about malaria elimination. The same decades of the '50s and '60s which saw progress in South America saw stagnation in most of Africa. The failure of malaria eradication in Africa and Asia led to the reappraisal of malaria eradication and to the WHA resolution of 1969, with subsequent retrenchments and, decades later, a shift to new technologies and techniques, notably long life bednets and intermittent presumptive therapy. In smallpox, Africa was at the origin of the successful modification to the original strategy, with surveillance and containment developed in the Biafra war and disseminated to all remaining endemic areas. In polio, Africa remained a major reservoir of infection through the last decades of polio eradication, largely because of social, political and religious factors in Nigeria, the last endemic country on the continent. The year long suspension of polio vaccination in northern Nigeria occasioned additional expenditures, in Nigeria and elsewhere, of over $500 million, slowing the global eradication effort. With measles, southern Africa became the test case for successful interruption of transmission, and remains so, amid setbacks linked to the slow progress of measles campaigns in other parts of the continent and to suboptimal follow-up campaigns in some countries. Among the six WHO regions, AFRO is one of two which have not opted for a regional elimination goal for measles. LESSONS LEARNED In every case, Africa is the touchstone for proof of concept. Once eradicability is demonstrated in Africa, worldwide eradicability becomes a more credible idea, and skepticism is discredited. Underestimating the African factor, as was done with the WHA malaria eradication of 1955, can have fatal consequences. Will rubella eradication move on to the global agenda in this century? This can happen if, and only if African governments take congenital rubella syndrome and its elimination more seriously than they currently do. Bob Davis UNICEF/ESARO Nairobi ______________________________________________________________________________ All members of the TechNet21 e-Forum are invited to send comments on any posting or to use the forum to raise a new discussion or request technical information in relation to immunization services. 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