WORLD HEALTH ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE
REGIONAL OFFICE FOR THE WESTERN PACIFIC BUREAU REGIONAL DU PACIFIQUE OCCIDENTAL
REGIONAL COMMITTEE Forty-ninth session Manila 14–18 September 1998 Provisional agenda item 11
WPR/RC49/7 23 July 1998 ORIGINAL: ENGLISH
ERADICATION OF POLIOMYELITIS IN THE REGION: PROGRESS REPORT This annual progress report details the current status of the regional poliomyelitis eradication campaign. Only nine cases of poliomyelitis were reported in the Region in 1997. That year was the first for which several countries recently endemic for poliomyelitis reported no cases of the disease. As no new wild-poliovirus-associated case of poliomyelitis has been detected since March 1997, there is good reason to believe that indigenous wild poliovirus transmission in the Region has finally ceased. In 1997, a total of 5848 cases of acute flaccid paralysis (AFP) were reported in the Region (data as at 20 March 1998). Of these, 4854 (83%) had two stool specimens collected within two weeks of onset of paralysis. Wild poliovirus was isolated from only nine of these cases, eight of them from Cambodia and one from the central region of Viet Nam. In response, all out efforts were made to ensure that transmission ceased by the end of 1997. From November 1996 to April 1998 Cambodia and Viet Nam conducted eight rounds of supplementary immunization in high-risk areas, and intensified their surveillance efforts. The results have been very encouraging. The last case of wild-poliovirus-associated poliomyelitis in the Region had onset of illness in Cambodia on 19 March 1997. The Regional Certification Commission met for the second time in Manila in November 1997, and reviewed the plans of action of eight non-endemic countries and areas, and of the Pacific islands subregion. At its third meeting in Brunei Darussalam in August 1998, the plans of action for certification in eight recently-endemic countries will be reviewed. All countries and areas are asked to ensure that AFP and virological surveillance is sustained at the levels of quality required for certification. In addition, supplementary
immunization must continue in high-risk areas to protect against the potential effects of importation of wild poliovirus from other regions, until global eradication is achieved.
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1. INTRODUCTION
At its thirty-ninth session in September 1988, the Regional Committee for the Western Pacific adopted resolution WPR/RC39.R15 on the eradication of poliomyelitis in the Region by 1995. Resolution WPR/RC41.R5 called for an annual report on eradication, and WPR/RC42.R3 and WPR/RC44.R4 proposed ways to accelerate the programme. Rapid progress has since been made towards the eradication of poliomyelitis in the Region.
2. PROGRAMME ACTIVITIES
2.1
Strengthening of routine immunization activities Routine coverage with oral poliovirus vaccine (OPV) has remained at over 90%. Most
countries and areas have sustained a high level of coverage for all Expanded Programme on Immunization (EPI) antigens, or consolidated recent gains, while simultaneously carrying out poliomyelitis eradication activities (Figure 1).
2.2
Supplementary immunization activities Supplementary immunization in the 1997–1998 low transmission season was carefully
planned with the aim of making certain that wild poliovirus transmission ceased by the end of 1997 (Table 1). Cambodia, the Lao People’s Democratic Republic and Papua New Guinea conducted National Immunization Days (NIDs), while China, Mongolia and the Philippines held Subnational Immunization Days (SNIDs). In addition, in early 1998, Cambodia and Viet Nam carried out two rounds of High-Risk Response Immunization (HRRI) for over 1 million children under five years of age in each country. From November 1997 to April 1998 Cambodia and Viet Nam have each carried out a total of eight rounds of supplementary immunization in high-risk areas. Mobile teams made visits from house to house or boat to boat on the waterways of the Mekong River to ensure that no child aged under five years of age would be missed. The numbers of children reached by mobile teams in these areas has increased, and there has been a marked decrease in the proportion of incompletely immunized children.
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2.3
Poliomyelitis surveillance Surveillance efforts have been equally intense (Table 2). In 1997, 5848 cases of acute flaccid
paralysis (AFP) were reported throughout the Region (data as at 20 March 1998). Of these, 83% had two stool samples taken within 14 days of onset of illness. However, after analysis in accredited laboratories, only 9 of the 5848 cases were confirmed as poliomyelitis by wild poliovirus isolation, which contrasts with the 6000 poliomyelitis cases reported in 1990 (see Figure 2). All recentlyendemic countries have now reached the standards of quality of surveillance needed to confirm poliomyelitis based on the isolation of wild poliovirus alone (virological confirmation). Thus, 1997 was the first year for which five countries recently classified as poliomyelitis-endemic (China, the Lao People’s Democratic Republic, Malaysia, the Philippines and Papua New Guinea) reported no poliomyelitis cases. The total number of poliomyelitis cases in the Region in 1997 was only nine. The last of these nine cases had onset of paralysis on 19 March 1997 in Cambodia. Since that case, almost 6000 AFP cases have been reported (data as at 20 March 1998), 85% of which had two stool samples taken within 14 days of onset. No wild poliovirus has been isolated from any of these cases. For 1998 (data as at 1 July 1998) under conditions of high-quality surveillance, every country in the Region is reporting zero poliomyelitis cases.
2.4
Interregional coordination Meetings on coordinating poliomyelitis eradication activities have been held between the
South-East Asia and Western Pacific Regions of WHO, at the regional and national levels. These meetings have resulted in the synchronization of supplementary immunization on the border between China and Myanmar, and in the exchange of surveillance information.
2.5
Certification of poliomyelitis eradication The Regional Commission for the Certification of Poliomyelitis Eradication in the Western
Pacific met for the second time in Manila in November 1997, and reviewed the plans of action of eight non-endemic countries and areas, and of the Pacific islands subregion. At its third meeting in Brunei Darussalam in August 1998, the plans of action for certification in eight recently-endemic countries will be reviewed. In these plans, recently-endemic countries describe the steps they will take to ensure that AFP and virological surveillance are improved and sustained at the levels of quality required for certification, and how they will continue with supplementary immunization in
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high-risk areas. As there is still a possibility of importation of wild poliovirus from other Regions until global eradication is achieved, all plans include measures to respond to potential importation.
2.6
Vaccine quality Under the regional plan of action for achieving self-sufficiency in vaccine production and
supply, technical support is being provided to several countries, with a major focus on strengthening of national quality control authorities. Expert missions, workshops and training fellowships have been carried out in collaboration with China, the Philippines and Viet Nam.
2.7
Resource requirements The rapid progress in poliomyelitis eradication would never have been possible without the
support of many international partners. They include UNICEF; the Governments of Australia, Japan, the Republic of Korea, and the United States of America through the Centers for Disease Control and Prevention in Atlanta; the Agency for Cooperation and International Health (ACIH); Rotary International and Rotary International Districts 2650 and 2640 of Japan. While the costs of providing vaccine for supplementary immunization are decreasing, the costs of sustaining surveillance during the certification period will remain the same, even though wild poliovirus no longer circulates in the Region. From 1992 to 1997, US$ 42.8 million was provided by international partners for the purchase of OPV for supplementary immunization (Figure 3). From 1992 to 1997, US$ 17.98 million was provided by international partners for staff, supplies and equipment, and operational costs for surveillance and supplementary immunization activities (Figure 4).
2.8
Major issues in poliomyelitis eradication and actions being taken The major issues facing poliomyelitis eradication and the actions being taken are presented in
Table 3.
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3. FUTURE ACTIVITIES
3.1
Supplementary Immunization From 1998 onwards, countries will no longer conduct full-scale national immunization days,
but will reduce the magnitude and extent of poliomyelitis by focusing supplementary immunization on high-risk areas. Successful strategies to reach previously unimmunized children in areas of difficult access will be further refined.
3.2
Laboratory and acute flaccid paralysis surveillance The performance indicators of each laboratory in the regional network will continue to be
monitored carefully.
In addition, all laboratories will undergo annual accreditation reviews.
Countries will sustain AFP surveillance activities while ensuring that all areas of the country are represented.
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Table 1. National immunization days and high-risk response immunization, 1992–1998a Western Pacific Region Country Subnational immunization days 1 Coverage Other antigens National and immunization supplements days 4 95% Vitamin A Number immunized per NID 1.9 million Total HRRI High-risk response immunization days May/June 1997 February/March 1998 Number immunized
Cambodia
2
1 million
China Lao P.D.R.
4 2
3 5
>90% 80%
Vitamin A, measles, Diphtheriapertussistetanus toxoid Diphtheria, tetanus toxoid, measles Measles, tetanus toxoid Vitamin A, tetanus toxoid, measles Vitamin A, tetanus toxoid, measles
70–83 million 650 000 1 May/June/July 1997 75 000
Mongolia
2
3
97%
300 000
Papua New Guinea Philippines
1 1
1 5
80% >90%
600 000 9.9 million
Viet Nam
1
5
>90%
9.7 million
2
May/June/July 1997 March/April 1998
1 million
a
TOTAL 12 Data as at 12 May 1998.
26
93–106 million
5
2.075 million
Table 2. Number of AFP cases reported, confirmed poliomyelitis cases and wild-poliovirus-associated cases, 1992–1997 Country Total number of AFP cases reported 1992 Cambodia China Lao PDR Malaysia Mongolia Papua New Guinea Philippines Pacific islands Viet Nam Others Western Pacific Region 146 2488 10 0 n.a. 73 47 0 653 0 3417 1993 135 1818 9 1 n.a. 16 88 0 607 1 2675 1994 301 3096 11 17 n.a. 13 126 1 353 1 3919 1995 183 4802 16 13 0 13 153 3 467 0 5650 1996 134 4376 41 32 19 14 175 6 495 3 5295 1997 181 4682 76 72 18 33 298 12 462 14 5848 1992 146 1191 7 3 1 0 13 0 557 0 1918 Confirmed as poliomyelitis (virological and/or clinical) 1993 135 538 7 0 2 0 15 0 452 0 1149 1994 297 307 6 0 0 2 11 0 121 0 744 1995 130 165 8 0 0 1 40 0 137 0 481 1996 84 3 21 3 0 4 80 0 2 0 197 1997b 8 0 0 0 0 0 0 0 1 0 9 1992 0 0 0 0 n.a. 0 8 0 26 0 34 Wild poliovirus isolated 1993 4 101 0 0 n.a. 0 7 0 157 0 296 1994 33 6 0 0 n.a. 0 0 0 35 0 74 1995 17 1a 0 0 0 0 0 0 13 0 61 1996 15 3a 1 0 0 0 0 0 2 0 21 1997 8 0 0 0 0 0 0 0 1 0 9
Latest data available from Regional Office Surveillance System as at 20 March 1998. n.a. not available a China wild virus imported. b Countries are shifting from clinical to virological case classification.
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Table 3. Major issues in poliomyelitis eradication and actions being taken MAJOR ISSUES Potential importation of wild poliovirus from neighbouring regions ACTIONS BEING TAKEN Maintain high-quality surveillance and supplementary immunization in border areas Adopt a plan of action to respond to possible importation of wild poliovirus Children in some high-risk areas (e.g. waterways, densely-populated urban areas) are often not easily accessible for routine immunization Some countries have silent or low-quality areas for AFP surveillance AFP surveillance must be sustained in the absence of poliomyelitis Resources for surveillance and supplementary immunization will be required until global eradication is certified Continue supplementary immunization in high-risk areas to prevent build-up of susceptible population Ensure all districts provide at least monthly reports including zero-reports Promote certification activities in every country through national certification committees Continue to seek funding support for surveillance, staff posts and OPV from partner agencies
Figure 1. Reported poliomyelitis cases and OPV3 coverage in the Western Pacific Region, 1980–1997 Number of cases 12000 10000 8000 6000 4000 2000 10 0 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 0
Routine OPV3 coverage (%) 100 90 80 70 60 50 40 30 20
Poliomyelitis cases
Routine OPV3
*
Source: CEIS and poliomyelitis surveillance reports, Regional Office, 12 May 1998 (1997 data provisional).
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Figure 2. Geographical distribution of poliomyelitis cases in 1997 compared with 1990 Western Pacific Region
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Figure 3. Partner support for oral poliovirus vaccine requirements, 1992–1997a Western Pacific Region
Total: US$ 42.8 million United States of America 13%
Rotary International 27%
UNICEF 13%
Others 4%
Japan 37% a
Australia 6%
Data as of 1 April 1998; includes committed as well as received funds.
Figure 4. Partner support for operational and surveillance requirements (non-OPV) for poliomyelitis eradication, 1992–1997b Western Pacific Region
Total: US$ 17.98 million
Australia 26% Japan 28%
Others 6%
ACIH 5% CDC/USA 13% b
As at 1 April 1998; includes committed as well as received funds.
Rotary International 22% (includes Rotary 2650 Japan)