The Death of a Disease: A History of the Eradication of Poliomyelitis

13. The Challenge of Eradication

132 The Death of a Disease 132 13 The Challenge of Eradication Spring 2003 As the year 2002 drew to a close, it became clear that the World Health Organization’s goal of eradicating all cases of polio caused by the wild virus would not be reached. Not only did the virus continue to spread, but the number of polio cases was higher than in 2001. In addition, virologists were troubled by another concern: cases of vaccineassociated polio were reported years after immunization campaigns with the oral vaccine. Eradicating polio would be more complicated than what had been generally expected. Worldwide, the successes of the polio campaign continued . On June 21, 2002, a meeting of the Regional Commission for Certification of Polio Eradication declared that polio had disappeared from the WHO European region, which included fifty-one countries and 870 million people. Cases of paralysis caused by imported viruses were reported in Bulgaria and Georgia in 2001, but no case of polio caused by a The Challenge of Eradication 133 locally contracted virus had been observed for more than three years. The condition for certification had been met. Europe was the third WHO region to be declared poliofree , following the Americas in 1994 and the Western Pacific in 2000. In 2001, the global incidence of polio had continued to drop, with 483 cases reported, seven times fewer than in 2000. The virus was circulating in only ten countries on two continents. No type 2 wild virus has been isolated since 1999, and it is possible that type 2 has been eliminated across the globe. In 2002, the number of polio endemic countries fell to seven, but the number of cases was on the rise in Egypt, Nigeria, and especially India. Globally the number of cases had increased to 1,918. In light of this paradoxical situation, while the prospects for eradication had improved overall, they had worsened in these three countries. For Bruce Aylward, coordinator of the Global Eradication Initiative, each of these three countries represents a special case, each with its own particular challenges, requiring an appropriate response. He explains: What is most disturbing in Egypt is that the cases are from different parts of the country. Genetically they are quite different, which means there is much more transmission than people have been recognizing. Numerous cases of polio have gone unreported. We collaborate with public health officials at the highest level to improve the reliability of the surveillance network. Four rounds of National Immunization Days (NIDs) were organized in 2003. Because there is so little polio in Egypt, and because of other factors, this should be able to eliminate the disease very fast. Cases in Nigeria are found in the northern part of this vast country. The pattern is not that of an epidemic 134 The Death of a Disease (when the number of cases explodes because of the rapid spread of the virus), but more of an endemic one (a steady number of annual cases, similar to what occurred in many countries before the eradication campaign started). Immunization campaigns were not carried out as effectively in this region of the country. The increase we are seeing no doubt corresponds to a marked improvement in surveillance. There are not more cases; we are simply better at finding them. We believed that surveillance for the entire country was as good as in the south, where infrastructures are betTable 13.1 Number of Cases of Polio in 2002, 2003, and 2004 Country 2002 2003 2004 Pakistan 90 103 23 India 1,600 225 34 Nigeria 202 355 476 Afghanistan 10 8 3 Benin* 0 2 6 Niger 3 40 19 Burkina Faso* 1 11 6 Central African Republic* 0 1 3 Cameroon* 0 2 1 Chad* 0 25 12 Ghana* 0 8 0 Togo* 0 1 0 Egypt 7 1 1 Lebanon* 0 1 0 Somalia 3 0 0 Zambia* 2 0 0 Sudan* 0 0 5 Guinea* 0 0 1 Mali* 0 0 2 Botswana* 0 0 1 Ivory Coast* 0 1 9 Total 1,918 784 602 * Virus imported from another country or under analysis. Source: Data centralized by the World Health Organization as of August 24, 2004, and compared with 2002 and 2003 (confirmed infections due to wild virus). The Challenge of Eradication 135 ter, and believed that the drop in the number of cases was greater than it actually was. Three local NIDs were organized...