The problem in Africa

Before the development of effective vaccines, poliomyelitis was a leading cause of permanent disability (Sabin, 1949). The World Health Organization has estimated that, in the absence of routine immunization against the disease, and the ongoing global effort to eradicate the causative viruses, at least 600 000 children would be permanently paralyzed by poliomyelitis each year (Sutter et al., 2008). Unfortunately, well into the twentieth century, it was often erroneously suggested that polio was not a serious public health problem in tropical, developing countries, including those in Africa, as it was postulated that early exposure of infants to the virus occurred when maternal antibodies levels were still high, thereby protecting them from paralytic disease.

However, since the 1970s, ‘lameness surveys’ in African countries clearly showed that post-polio paralysis occurred at the same rate as in Europe and America in the pre-vaccine era (Nicholas et al., 1977; Mabey, 1981) (Fig. 38.1). Overall, five to ten cases of lameness were reported per 1000 children. Consequently, the oral poliovirus vaccine (OPV) was eventually included in the basic course of vaccines recommended by the Expanded Programme on Immunization (EPI) in 1974. From the mid 1970s to 1990, the intensification of national EPI programmes improved OPV coverage and polio control throughout Africa and the rest of the world. These achievements were not uniform, though, such that by the late 1980s the majority of countries with <50 per cent coverage were in Africa, as well as a disproportionate share of the world's polio burden.