WORLD HEALTH ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE
REGIONAL OFFICE FOR THE WESTERN PACIFIC BUREAU REGIONAL DU PACIFIQUE OCCIDENTAL
REGIONAL COMMITTEE Forty-fifth session Kuala Lumpur 19-23 September 1994 Provisional agenda item 10
WPRlRC4517 1 July 1994 ORIGINAL: ENGLISH
ERADICATION OF POLIOMYELITIS IN THE REGION: PROGRESS REPORT
This is the fourth annual poliomyelitis eradication progress report prepared in response to Regional Committee resolution WPRlRC41.R5. A provisional total of 1214 cases of poliomyelitis was reported from countries in the Region in 1993, the lowest total ever reported to WHO, despite further improvements in disease surveillance. This is a decrease of 40% from the 1912 cases reported in 1992. In 1993, over 100 million children were immunized across the Region during national immunization days in China, the Lao People's Democratic Republic, the Philippines, and Viet Nam, and subnational immunization days in Cambodia. All five of these countries are committed to
national immunization days during the months of low transmission in 1994-1995. The Region is on target to achieve the 1995 poliomyelitis eradication goal. Government support and commitment to poliomyelitis eradication is now very strong, but must be sustained. Member States are urged to
maintain their
commitment to improving acute flaccid paralysis surveillance to detect all poliomyelitis cases, and to conduct supplementary immunization activities in the countries reporting cases.
WPR/RC4S17 page 2
1. INTRODUCTION
The Regional Committee for the Western Pacific adopted resolution WPRlRC39.RI5 on the eradication of poliomyelitis in the Region by 1995 at its thirty-ninth session in September 1988. Resolution WPRlRC41.R5 called for an annual report on eradication, and WPRlRC42.R3 and WPR/RC44.R4 proposed ways to further accelerate the programme. This report deals with the current status of poliomyelitis eradication in the Region, including achievements and constraints, and planned activities in 1994.
2. PRESENT EPIDEMIOLOGICAL SITUATION In the Western Pacific Region, a provisional total of 1214 poliomyelitis cases was reported in 1993 (see Figure), by five of the six poliomyelitis-endemic countries in the Region (Cambodia, China, the Lao People's Democratic Republic, the Philippines and Viet Nam). The sixth of these countries. Papua New Guinea, reported zero cases for the third consecutive year, but the disease surveillance system is not yet functioning sufficiently well to declare the country non-endemic for pOliomyelitis. The total of 1214 cases is the lowest yet reported to WHO. It is a reduction of 40% from the total of 1912 cases reported in 1992. This reduction has largely been due to large-scale _ supplementary immunization with oral poliovirus vaccine (OPV) in China, the Philippines and Viet Nam. The lower total number of poliomyelitis cases has occurred despite further improvement by countries of their surveillance systems for reporting and investigating cases of acute flaccid paralysis. This is necessary for the detection of all cases of poliomyelitis.
WPRlRC4S17 page 3
Figure
Reported poliomyelitis cases and OPV3 coverage in the Western Pacific Region, 1980-1993
Number of cases 12000
OPV3 coverage (%)
r-----------------------------------------------------,-100 80 10 70 10000
1000 1000
60
50 40 4000
30 20
2000 10
o
o
80 81 82 83 84 85 86 87 88 89 90 91 92 93*
•
Poliomyelitis cases
-
OPV3
* 1993
data provisional (Ill acute flaccid paralysis cases are still under investigation. )
Source: Poliomyelitis Surveillance Reports, 6 April 1994.
WPRIRC4S17 page 4
Cambodia reported 135 cases in 1993, but this is a considerable underestimate of the poliomyelitis situation in the country. As the surveillance system undergoes further development and becomes more accurate, this figure is expected to rise (see Table 1). In China and Viet Nam, poliomyelitis transmission is still widespread although the number of cases is reducing.
Table 1. Confinned poliomyelitis cases and proportion of provinces or regions with confinned poliomyelitis cases in poliomyelitis-endemic
countries of the Western Pacific Region, 1991-1993
1991 Poliomyelitis cases 84 1926 % of regions! provinces reporting conrrrmed poliomyelitis
1992 Poliomyelitis cases 146 1191 7 % of regions! provinces reporting conrll"Med poliomyelitis
1993' Poliomyelitis cases 135 653 % of regions! provinces reporting confirmed poliomyelitis
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Country
Cambodia China Lao People·s Democratic Republic Papua New Guinea Philippines Viet Nam WPR TOTAL
57 100 6
71 100 24
71 83 24
2
7
0 II
0 29 89
0 8 557 1912
0 36 74 .
0
0 20*** 77
6··· 413 1214
612 2635"
Note: '1993 data proviSional as at 9 May 1994. "Including imported cases in countries where the disease is not endemic. "'To be confirmed by expert panel.
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Source:
WPRO Poliomyelitis Surveillance Reports, June 1994.
The Region is making good progress and, if the above trend continues, is on schedule to meet the 1995 poliomyelitis eradication goal.
WPRlRC45/7 pageS
3. PROGRAMME ACTIVITIES
3.1
Supplementary immunization activities
During the months of low transmission in 1993-1994, China, the Lao People's Democratic Republic, the Philippines and Viet Nam held two rounds of national immunization days during which all children under the age of five years (under four years in China) were targeted to receive supplementary doses of OPV. (see Table 2). Cambodia held subnational immunization days in two provinces
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Table 2. Results of immunization days held in the Western Pacific Region 1992-1993, 1993-1994, and planned for 1994-1995
1992-1993
1993-1994
Planned 1994-1995
Country
Number or provinces or districts covered
Coverage
rortwo
OPV"
doses
0'
Targd population ror OPV (mlllious)
Numbe.or proviDces
Estimated
or distrid.s cowered
coverage for two doses of OPV"
Tar," population fo.OPV (millions)
Numb... or provinces
or districts to cover
TBrI" population f.rOPV (millions)
Cambodia 29130 provinces 481128 provinces
2121 provinces
88%
0.3
NID
1.7
NID
80%
100
NID
100
China Lao People' 5 Democratic Republic Philippines
77%
0.33
1041129 districts
>80%
0.6
NID
0.8
NID' 8153 provinces
90% 90%
9.S 1.3
NID NID
>90% >90%
9.5 9.8
NID NID
9.5
to.O
Viet Nam
Note: *NationaI immunization days (covering entire country) **The lowest coverage figure of the two rounds is shown as an estimate of the coverage for two doses ofOPV. Source: WPRO Poliomyelitis Surveillance Reports, June 1994.
WPRlRC4S17 page 6
The results were very encouraging. In all the countries involved the national immunization days were a credit to their governments' planning and organizational abilities, and their skills in social mobilization. Very high coverage with OPV was achieved, and in some countries vitamin A and other antigens were offered for selected eligible groups or areas. 3.2 Poliomyelitis surveillance
Surveillance activities are continuing to make impressive progress in the five countries that have established acute flaccid paralysis surveillance nationally. Cambodia has commenced acute flaccid paralysis surveillance in Phnom Penh, with plans to extend the system to all provinces in 1994. Further improvements in national surveillance systems are required, even in poliomyelitisfree countries, particularly those bordering on countries where the disease is endemic. The risk of imported cases of poliomyelitis is demonstrated by the three cases reported by Malaysia in 1992. The laboratory system is now well established and has improved considerably, as the results of proficiency tests show. However, there is still a need for improvement in areas such as virus isolation, timely testing of samples, timely reporting of results, and coordination with case investigation. performance. Resources are required, particularly for equipment, to improve laboratory _
3.3
Vaccine quality
Since the last progress report, all OPV used in poliomyelitis-endemic countries, with the exception of China, has been imported and meets WHO/UNICEF potency and safety standards. The OPV pill (dragee) produced in China meets national potency and safety standards. The Fifth Meeting of the Technical Advisory Group on Expanded Programme on Immunization and Poliomyelitis Eradication in the Western Pacific Region, held in April 1994, discussed the issue of the quality of OPV produced in the Region. The Group endorsed the continued use of OPV produced in China, based on an evaluation of field data which showed good efficacy. The Group agreed with the decision of the Ministry of Health, Viet Nam, on the process to be followed in finalizing procedures for release of locally produced OPV for national use. The Global Advisory Group recommendation, that OPV is the vaccine of choice for poliomyelitis eradication, is still in force. issues and considerations of price and supply. The reasons include operational and epidemiological
-
WPRlRC4517 page 7
3.4
Resource requirements The majority of the resources for the Expanded Programme on Immunization and
poliomyelitis eradication continue to come from the countries themselves, supplemented by support from the international community. In addition to funds mobilized for the routine programme on immunization, approximately US$ 30 million has been mobilized from the international community for poliomyelitis eradication activities in the Region from 1990 to 1994. This includes funds for oral poliovirus vaccine, staff and operational expenses. Of this amount, two-thirds have been At the Fourth Regional provided bilaterally, with the remainder provided through WHO.
Interagency Coordinating Committee meeting (held during the Technical Advisory Group meeting
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in April 1994) additional funds were pledged by Australia, Canada, Japan, the United States of America and Rotary International. Further funds are still required for OPV, and for operational expenses related to carrying out the national immunization days, particularly for Cambodia, the Lao People's Democratic Republic and Viet Nam. Vaccine is also required for extended outbreak response immunization when The regional transmission of wild poliovirus is occurring in only a few places in countries. working to obtain the required funds. 3.5 (a) Constraints and problems Surveillance and laboratory services: Countries still have low rates of reporting of acute flaccid paralysis cases. investigation is not always adequate. There are delays in processing laboratory specimens. Countries where poliomyelitis is not endemic do not yet have sufficiently well developed surveillance systems for acute flaccid paralysis. (b)
interagency coordination committee, and national committees in the respective countries, are
--
Case
Supplementary immunization A shortfall of OPV for supplementary immunization still remains. There are pockets of low coverage during national immunization days.
WPR/RC4S/7 page 8
"
(c) Cross-border coordination At this stage of poliomyelitis eradication, coordination of poliomyelitis surveillance and immunization activities needs to be improved between countries and other WHO regions.
4. FUTURE ACTIVITIES
Five of the six poliomyelitis-endemic countries are now committed to conducting national immunization days in the months of low transmission in 1994-1995. Following the success of supplementary immunization activities held in 1993-1994, there is every reason to expect that the coming national immunization days will be well planned and executed, and achieve high coverage of eligible children with OPV. national immunization days. With the commitment of countries to national immunization days it is expected that the number of cases of poliomyelitis will fall considerably in 1994 and 1995. Surveillance for acute flaccid paralysis therefore becomes increasingly important to detect all cases of poliomyelitis, and to determine where the wild poliovirus is still circulating. In 1994, WHO will collaborate with all countries to further improve surveillance and laboratory systems, with the objective of reaching a level of performance which will allow the eventual certification of poliomyelitis eradication. WHO will continue to coordinate the activities of all collaborating agencies and organizatiOns to obtain adequate resources to achieve the 1995 eradication goal. WHO will continue to work with countries and collaborating agencies to coordinate supplies of OPV to enable poliomyelitis-endemic countries to conduct
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