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Global Progress Toward Certifying Polio Eradication and Laboratory Containment of Wild Polioviruses --- August 2002--August 2003
Since the 1988 World Health Assembly resolution to eradicate poliomyelitis, the number of countries in which polio is endemic has declined from 125 to seven. These countries are in three of the six World Health Organization (WHO) regions (i.e., African, Eastern Mediterranean, and South East Asian) (1). The other three regions (i.e., Americas, European, and Western Pacific) were certified previously as polio-free (2--4). This report summarizes the progress made toward global certification of poliomyelitis eradication and implementation of measures to ensure laboratory containment of wild polioviruses (WPVs). The findings indicate that, although much progress has been made, wide disparities in certification and laboratory-containment capabilities underscore the need for continued efforts to verify the eradication of polio worldwide.
Certification Definitions and Operating Procedures
The Global Certification Commission (GCC) will declare the world free of WPV transmission when no WPVs have been found by certification-standard surveillance for 3 consecutive years and all laboratories with WPV-containing materials have adopted appropriate containment measures (5). GCC was appointed by WHO in 1995 and oversees certification of global polio eradication through Regional Certification Commissions (RCCs) and National Certification Commissions (NCCs). RCCs are now functioning in all WHO regions. As of August 2003, NCCs had been established in all WHO member states except Somalia (Eastern Mediterranean Region), Monaco and San Marino (European Region), and East Timor (South East Asian Region).
To meet certification standards, an acute flaccid paralysis (AFP) surveillance system must each year detect at least one nonpolio AFP case per 100,000 persons aged <15 years, collect two adequate stool specimens* from >80% of persons with AFP, and test all stool specimens for poliovirus at a WHO-accredited laboratory.
The laboratory-containment requirements for global certification of polio eradication are outlined in the WHO global action plan for laboratory containment of WPVs (5). In phase I, each country conducts a national survey to create an inventory of biomedical laboratories holding WPV-infectious or potentially infectious materials. Phase II will begin after 1 year with no WPV found anywhere in the world. This phase requires destruction of all unneeded stocks of WPV and containment of retained WPV stocks under appropriate biosafety conditions. Documentation of these efforts from all countries is required for global certification.
Surveillance and Containment in Polio-Free Regions
On August 20, 1994, the Americas Region was certified as polio-free. At that time, both the RCC and country-level NCCs were dissolved, leaving no independent groups monitoring activities to maintain the region's polio-free status. However, through the efforts of individual countries and WHO, certification-standard AFP surveillance has been maintained in most countries of the region. At the time of the Americas Region certification, laboratory containment was not required. To meet the new requirements, all countries in the region have appointed national containment task forces. Laboratory surveys are under way in 47 of 48 countries, with surveys completed in 99,630 (90%) of 110,254 laboratories and institutions registered for survey (Table). All countries are expected to submit a report to a new RCC, to be established in early 2004.
On October 29, 2000, the Western Pacific Region was certified as polio-free. As of August 2003, the RCC, NCCs and a subregional committee for Pacific Island countries maintain active efforts to sustain polio-free status and to monitor the progress of laboratory containment. By August 2003, laboratory surveys had been completed in all Western Pacific Region countries except China and Japan, with 12,691 (72%) of 14,977 laboratories and institutions surveyed. China and Japan are expected to complete their activities in 2004.
On June 21, 2002, the European Region was certified as polio-free. At the time of certification, laboratory surveys had been completed in 41 of 51 countries, with 39,130 (91%) of 43,018 laboratories and institutions surveyed. Completion of phase I activities in all countries of the region is expected in 2004. The European Region RCC meets annually to monitor the polio-free status of the region and to ensure completion of the containment activities.
Certification and Containment in Regions with Endemic Polio
In countries where polio is endemic, interrupting the spread of virus is a higher priority than certification and containment activities. However, certain countries that have not reported a case of polio in years have made considerable progress toward certification and containment.
NCCs have been established in all Eastern Mediterranean Region countries except Somalia, for which WHO and the United Nations Children's Fund (UNICEF) will facilitate certification activities; 16 of the 22 NCCs have begun reporting to the RCC. Documentation claiming polio-free status has been provisionally accepted from nine countries. Laboratory surveys have been started in 16 of 23 countries in the region and completed in five. The most critical obstacle to containment is obtaining information from the numerous unregistered biomedical laboratories that operate in the region.
In the South East Asian Region, East Timor is the only country without an NCC. Full national documentation has been reviewed from Sri Lanka and Thailand, both with no WPV for >3 years. Bangladesh and Nepal will be the next countries to present full national documentation. Laboratory-containment activities have begun in all countries in the region, and two countries have completed the process; 3,427 (52%) of 6,650 laboratories and institutions have been surveyed.
Certification activities in the African Region began in 1998. The RCC continues to train and orient NCCs in the region's 46 countries, several of which were established recently. RCC members also are beginning to conduct country visits to advocate improvements in surveillance and supplementary immunization activities. Containment activities have begun in Cameroon, Guinea-Bissau, Senegal, Tanzania, Togo, and Uganda. Information gained from the experiences of these countries will be used to introduce phase I containment activities in the remaining countries in 2004.
Reported by: Vaccines and Biologicals Dept, World Health Organization, Geneva, Switzerland. Global Immunization Div, National Immunization Program, CDC.
Activities to certify eradication of WPV are an essential component of the global polio eradication initiative. Success of the certification process depends on 1) application of lessons learned from global smallpox eradication efforts and polio eradication in the Americas and 2) integration of key new program elements such as laboratory containment of WPVs. The soundness of the certification process is supported by the inability of certification-standard AFP surveillance to detect indigenous WPV in any of the three regions certified as polio-free.
However, several challenges remain. Not all NCCs in regions in which polio is endemic have attained the level of expertise needed to assess and verify data critically. Also, RCCs must work together more closely to scrutinize data from areas that share common chains of virus transmission but belong to more than one WHO region (e.g., the Horn of Africa). Efficiently coordinating certification activities across regions will require regular joint meetings of RCCs.
Ensuring effective laboratory containment at the time of global certification is critical to maintaining the achievements of polio eradication. Toward this end, GCC has identified the need for appropriate expertise in biosafety and polio eradication to advise on the status of containment, including means of verifying the absence of circulating vaccine-derived polioviruses.
Regions already certified as polio-free have faced decreases in interest and support from national governments. Sustaining certification-level surveillance and containment are possible only through continued commitments from national governments and ministries of health and through the support of scientists and public health experts who donate their time to certification committees. These continued efforts will be necessary to document and certify the global interruption of WPV transmission and guard against any reemergence of poliovirus.
* Stool specimens are considered adequate if two specimens are collected at least 24 hours apart, within 14 days of onset of paralysis, and arrive in the laboratory in good condition.
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