Poliomyelitis in selected African and Asian countries.

The most common cause for the persistence of poliomyelitis in developing countries has been the failure of routine immunization programs to provide > or = three doses of poliovirus vaccine to a high proportion of infants. However, a more worrisome pattern of disease can be attributed more to vaccine failure than failure to vaccinate, as illustrated by epidemics in selected African and Asian countries during the 1980s. The efficacy of oral poliovirus vaccine (OPV) has been shown in these and other instances to be considerably lower in developing countries than in industrialized countries, indicating that reliance on routine administration of OPV alone will not be sufficient to achieve global eradication of wild poliovirus transmission. Because more aggressive approaches will likely be needed to achieve global eradication of poliomyelitis, various tactics have evolved over the past decade. The most promising approach has been the use of biannual national vaccination days, which have been used with great success in Latin America. However, these campaigns have certain drawbacks, including enormous OPV requirements and difficult logistics. A second approach, which has been used primarily in the West Bank and Gaza, involves the use of combined schedules of OPV and enhanced-potency inactivated vaccine (IPV). This approach requires far fewer contacts and doses of OPV; allows for more reliable and consistent serum neutralizing antibody responses in both the short- and long-term; and for boosting of secretory antibody responses in both the nasopharynx and gastrointestinal tract.(ABSTRACT TRUNCATED AT 250 WORDS)