Polio Eradication in the World Health Organization South-East Asia Region by the Year 2000: Midway Assessment of Progress and Future Challenges

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1 S89 Polio Eradication in the World Health Organization South-East Asia Region by the Year 2000: Midway Assessment of Progress and Future Challenges Jon K. Andrus, Kaushik Banerjee, Barbara P. Hull, Jean Clare Smith, and Imam Mochny Expanded Programme on Immunization, World Health Organization Regional Office for South-East Asia Region, and Maternal Child Health Division, Department offamily Welfare, Ministry ofhealth and Family Welfare, New Delhi, India; Global Programme on Vaccines and Immunization, World Health Organization, Geneva, Switzerland; Centers for Disease Control and Prevention, Atlanta, Georgia In the South-East Asia Region (SEAR) of WHO, paralytic poliomyelitis has decreased from 25,711 cases in 1988 to 3304 cases in 1995, representing an 87% reduction. By 1995, in 6 of 10 member countries-india, Bangladesh, Myanmar, Nepal, Indonesia, and Democratic People's Republic of Korea- polio remained endemic. Two countries, Sri Lanka and Thailand, appear close to polio eradication, and 2, Bhutan and Maldives, reported no cases during Although reported rates of acute flaccid paralysis and the percentage of cases virologically investigated are low in some countries, no isolates of wild poliovirus type 2 have been reported outside India since By the end of 1996, all 8 countries in which polio is endemic will have conducted national immunization days for polio eradication. The major challenge for polio eradication in SEAR will be strengthening surveillance, because national immunization days alone cannot eradicate polio. From 1988 to 1995, countries ofthe South-East Asia Region (SEAR) of the World Health Organization (WHO) annually reported more than half of the polio cases globally [1]. To achieve the global goal of polio eradication by the year 2000, it is of critical importance that countries of SEAR implement and sustain the necessary strategies. Since the global polio eradication initiative was first adopted by the World Health Assembly in 1988, most of the global progress toward polio eradication has been highlighted by the achievements of the Americas and, more recently, of the Western Pacific Region [1-4]. During , global progress was noteworthy for the dramatic acceleration of polio eradication activities in SEAR, particularly with the implementation of national immunization days (NIDs) and with efforts to strengthen stfrveillance of acute flaccid paralysis (AFP) and wild poliovirus. In SEAR, the strategies to eradicate poliomyelitis are similar to those developed in the Americas [2]. These strategies, recommended globally by WHO [5], include strengthening routine vaccination coverage, supplementing routine immunization services with NIDs in all countries in which polio is endemic, expanding surveillance of AFP and wild poliovirus so that all cases of polio are identified and investigated, and conducting house-to-house "mop-up" immunization campaigns in the remaining areas sustaining transmission of wild poliovirus after NIDs have been implemented. Presented at the 6th meeting on the Global Poliomyelitis Eradication Initiative, World Health Organization and Centers for Disease Control and Prevention, July 1995, Atlanta. Reprints or correspondence: Dr. Jon Kim Andrus, South-East Asia Regional Office for WHO, Indraprastha Estate, New Delhi , India. The Journal of Infectious Diseases 1997; 175(8uppl 1): by The University of Chicago. All rights reserved /97/ $01.00 This report summarizes the progress achieved in SEAR toward polio eradication from 1988 through 1995 and is based on data reported to the SEAR office through 30 April Coverage data are reported from 1988 through The 10 member countries of SEAR are Bangladesh, Bhutan, Democratic People's Republic ofkorea (DPR Korea), India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, and Thailand. When reported, results of intratypic characterization of polioviruses are included. The data source and date for country population estimates is the United Nations Population Division, OPV Immunization Coverage In 1990, 8 member countries in SEAR reported that they had reached the 1990 Universal Childhood Immunization goal of coverage among children 1 year of age of > 80% with three doses of diphtheria-pertussis toxoids-tetanus vaccine, three doses of oral poliovirus vaccine (OPV3), and one dose ofmeasles vaccine. Regionally, reported immunization coverage for OPV3 by 1 year of age has been sustained above 80% since However, low-coverage areas exist in all countries, including those countries reporting coverage levels of >90%. In 1994, Bangladesh (95%), Bhutan (84%), DPR Korea (99%), India (92%), Indonesia (91%), Maldives (97%), Sri Lanka (88%), and Thailand (93%) reported a coverage of ;:,80% for OPV3. Mongolia (77%) (now a member country of WHO's Western Pacific Region), Myanmar (77%), and Nepal (64%) reported coverage of <80% in Regional Progress From 1988 through 1995, the number ofpolio cases reported in SEAR decreased by 87%, from 25,711 to 3304 (figure 1).

2 S90 Andrus et al. JID 1997;175 (Suppll) en 'tj i 30 o 525 s: t:. II) 20 CD II) ~ 15 '0 10 Gi.0 E 5 :::J Z 35, , o Year of Paralysis Onset Figure 1. Reported paralytic poliomyelitis by year ofparalysis onset, India (rule) and South-East Asia Region (bars), Source: Ministry of Health, member countries. However, in 1995, cases reported from SEAR accounted for more than half of the cases of paralytic poliomyelitis reported worldwide. In 1995, four subcontinent countries-india, Bangladesh, Myanmar, and Nepal-accounted for 99% (3283/ 3304) of all the cases reported in SEAR. Other member countries in which polio is endemic are DPR Korea, Indonesia, Sri Lanka, and Thailand. By 1995, 6 of the 8 member countries in which polio is endemic-bangladesh, India, Indonesia, Nepal, Sri Lanka, and Thailand-were conducting AFP surveillance (table 1). Of these countries, Sri Lanka and Thailand routinely monitor and evaluate AFP reporting rates, the timeliness of AFP reporting and investigation, and the collection of 2 stool specimens within 2 weeks of onset of paralysis. By May 1996, with the exception of DPR Korea, all countries in which polio is endemic will have implemented AFP surveillance. In 1993, the SEAR Polio Laboratory Network was established, consisting of three regional reference laboratories and eight national laboratories. The reference laboratories are located in the National Institute of Communicable Disease (NICD) in New Delhi; Medical Research Center in Colombo, Sri Lanka; and Virus Research Institute (VRI) in Bangkok. The eight national laboratories are located in India (King Institute of Preventive Medicine in Madras, Enterovirus Research Center in Bombay, Central Research Institute in Kasauli, and Pasteur Institute of India in Conoor), Bangladesh (Institute of Public Health in Dhaka), and Indonesia (National Institute of Health Research and Development in Jakarta, Perum Bio Farma in Bandung and Laboratory Health Services in Surabaya). Virologists at the national laboratories use traditional virologic cell culture techniques for poliovirus isolation and typing. Polioviruses isolated at the national laboratories are sent to the appropriate regional reference laboratories for intratypic characterization using ELISA and nucleic acid probe hybridization techniques. In 1993, only 917 AFP cases were reported to have virologic investigation, with a total of 1601 stool specimens being processed for viral culture. In 1995, provisional data indicate that 1287 AFP cases were reported to have virologic investigation, with a total of 1802 stool specimens being processed for viral culture. In 1995, 63% of all polioviruses isolated in the region underwent intratypic differentiation. Progress by Country India (population 935,744,000). Most of the SEAR progress toward polio eradication primarily reflects achievements Table 1. Rates of reported acute flaccid paralysis (AFP) per 100,000 persons aged <15 years in countries in which polio is endemic, by year, South-East Asia Region, % of reported cases in 1995 with stool specimens Country collected for viral culture Bangladesh % DPR Korea NR NR NR NR NR NA India NR NR NR NR 2.2 NA, AFP surveillance implemented in 1995 Indonesia NR NR NR % Myanmar NR NR NR NR NR NA, AFP surveillance to be implemented in 1996 Nepal < % Sri Lanka %* Thailand NR %* NOTE. NR, not reported; NA, not available. Surveillance indicators are used to monitor performance of reporting and investigation of AFP cases. Besides AFP reporting rates per 100,000 persons < 15 years old, indicators include % of AFP cases virologically investigated and % of AFP cases with 2 stools collected for viral culture <2 weeks after paralysis onset. India, Bangladesh, and Nepal target AFP surveillance toward children <5 years old, and rate is expressed accordingly. * % of cases with 2 stools collected <2 weeks after paralysis onset for viral culture.

3 JID 1997; 175 (Supp11) Polio Eradication in South-EastAsia Region S91 in India, where reported polio cases declined 87% during , from 24,257 to Recently, this progress has leveled (figure 1). In India, the number of polio cases decreased by 54% from 1992 (9203) to 1993 (4236), followed by a 13% increase from 1993 (4236) to 1994 (4791), and then decreased by 34% from 1994 (4791) to 1995 (3142). Among cases with age information, the median age for polio cases reported during was 18.0 months for each year and has remained relatively unchanged from reports 10 years previously [6, 7]. The proportion of cases <36 months ofage has ranged from 79% in 1992 to 82% in 1993 and The proportion of cases < 48 months of age has ranged from 88% in 1992 to 91% in 1993 (table 2). In 1994, of the 2691 reported cases of paralytic poliomyelitis for which OPV immunization history was available, 64% had no doses ofopv, 12% had one or two doses, and 24% had three or more doses. Analysis of polio cases reported by month suggests that India is still reporting an episodic or seasonal pattern of disease (figure 2). In 1994, outbreaks of polio occurred more focally in the states of Gujarat and Karnataka (figure 3). From 1993 to 1994, Gujarat experienced a 6-fold increase in reported poliomyelitis cases, from 120 to 750. The number of poliomyelitis cases more than doubled in Karnataka from 1993 (301) to 1994 (668). In 1993, 14% (604/4236) of polio cases reported in India to the SEAR WHO office had stools collected for viral culture; of these, 32% (193/604) had polioviruses isolated. Of the 193 cases with polioviruses isolated, 24% (46/193) had type 1,24% (46/193) had type 2,31% (59/193) had type 3, 18% (34/193) had mixtures, and 4% (8/193) had unknown results. In 1994, 22% (1075/4791) of polio cases reported in India to the SEAR WHO office had stools collected for viral culture; of these, 37% (397/1075) had polioviruses isolated. Ofthe 397 cases with polioviruses isolated, 75% (299/397) had type 1, 9% (35/397) had type 2, 11% (42/397) had type 3, and 5% (21/397) had mixtures. In 1995,32% (1004/3142) of polio cases reported in India to the SEAR WHO office had stools collected for viral culture; of these, 31% (313/1004) had polioviruses isolated. Ofthe 313 cases with polioviruses isolated, 57% (177/313) had type 1, 12% (38/313) had type 2, 22% (69/313) had type 3, and 9% (29/313) had mixtures. From 1993 to 1995, the proportion of poliovirus type 2 isolates was 24% in 1993, 11% in 1994, and 12% in Of Table 2. Reported number of cases of paralytic poliomyelitis in children <36 months and <48 months old, India, No. of polio cases reported No. with age information % <36 months % <48 months the 42 poliovirus type 2 isolates reported from the SEAR Polio Laboratory Network in 1995, 38 were reported from India (6 Bombay, 26 New Delhi, 1 Kasauli, and 5 Madras). The other 4 (1 in Thailand, 2 in Sri Lanka, and 1 in Indonesia) were characterized as vaccine-related. The capacity for intratypic characterization of polioviruses by the NICD Regional Reference Laboratory has expanded since receiving the necessary reagents in In 1994, NICD reported characterizing 28 poliovirus isolates selected from specimens processed in 1993: 8 wild type 1, 8 wild type 2, 9 wild type 3, 2 vaccine-related type 1, and 1 vaccine-related type 2. In the first semester of 1995, NICD provisionally reported characterizing 146 poliovirus isolates: 62 wild type 1, 21 wild type 2, 42 wild type 3, 2 vaccine-related type 1, 5 vaccinerelated type 2, 4 vaccine-related type 3, and 10 polioviruses pending. In 1993, Kerala became the first state in India to conduct statewide immunization days, targeting all children <3 years of age on a single day, and in 1994 repeated this activity. Kerala reported 59 cases ofparalytic poliomyelitis in 1992, 80 cases in 1993, 7 cases in 1994, and 3 in The last cultureconfirmed case of paralytic poliomyelitis in Kerala was reported in July In early 1994, Tamil Nadu became the second state to conduct statewide immunization days. Delhi, the seat of the nation's capital, became the third state, conducting statewide immunization days on 2 October 1994, Mahatma Gandhi's birthday. Of note, Delhi authorities incorporated an extensive social mobilization campaign, including the recruitment of hundreds ofvolunteers, schools, newspapers, radio, and television networks [8]. Of the> 1 million children <3 years of age targeted in the State, 92% received OPV. After the success of statewide immunization days in Delhi, Tamil Nadu, and Kerala, the central Government of India conducted its first NIDs in December 1995 and January 1996, calling them Pulse Polio Immunization Days. More than 75 million children <3 years of age were targeted nationwide to receive supplemental OPV. On 9 December 1995, health authorities and volunteers immunized 87.8 million children with OPV, of which 79.3 million (90%) were <3 years old. Thirty-one ofthe 32 States and Union Territories reported firstround coverage to be >90% (Nagaland, population 1.3 million, reported coverage of 86%). On 20 January 1996, the Government of India immunized 93.6 million children with OPV, of which 85.4 million (90%) were <3 years old. Bangladesh (population 120,433,000). In 1995, Bangladesh reported 108 cases of polio, an 80% decline from the 540 cases reported in In 1993, 26% (61/233) ofthe cases of AFP had stool specimens collected for viral culture; of these, 28% had polioviruses isolated. Of the 17 cases with polioviruses isolated, 16 (94%) had poliovirus type 1 and 1 (6%) had poliovirus type 2. In 1994,43% (123/289) ofthe cases reported had stool specimens collected for viral culture; of these, 7% (9/123) had polioviruses isolated. In 1994, of the cases with

4 S92 Andrus et al. JID 1997; 175 (Suppl 1) 1,600, , en a> en CO o -o l0- a>.0 E::J Z Ol ' Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month of Onset of Paralysis polioviruses isolated, 6 had type 1 isolated and 3 had type 3 isolated. In 1995, 53% (57/108) ofthe cases reported had stool specimens collected for viral culture; of these, 4% (2/57) had polioviruses isolated. Of the cases with polioviruses isolated, both had type 1. During , no poliovirus type 2 isolates were reported. In March 1995, Bangladesh became the second country in SEAR to conduct NIDs, reaching 95% of the targeted 18.9 million children < 5 years of age in the country with at least one dose of OPV and 83% with two doses of OPV. For the first round, coverage ranged from being the lowest (47%) in periurban areas of Dhaka to >90% in other cities. The input ofan evaluation conducted by independent observers during the first round contributed to significant improvements in secondround performance 1 month later in April. In periurban areas of Dhaka, coverage increased to 76% during the second round, confirmed by Expanded Programme on Immunization (EPI) cluster surveys. Myanmar (population 46,527,000). In 1995, Myanmar reported 24 cases of polio, a 60% decline from the 60 cases reported in In 1987, OPV3 coverage among children 1 year of age was only 10% compared with 77% reported in Concomitant with this progress has been the expansion of the population covered by EPI and other primary care services. In 1991, 211 of 320 townships were covered by EPI services. Over the next 2 years, the remaining 109 townships not covered by EPI were targeted for inclusion. By 1995, only 17 townships remained not covered by some degree of EPI services. Many of the 17 townships border the emerging "polio-free" zones of China and Thailand. The Government of Myanmar conducted its first NIDs on 10 February 1996 and 10 March Because China will be conducting its third, and last, NIDs beginning in December Figure 2. Reported cases of paralytic poliomyelitis cases by month and year ofpa ralysis onset, India, January 1992-December Source: Ministry of Health and Family Welfare, India. 1995, the timing of the NIDs in Myanmar was epidemiologically critical for expanding polio-free zones of neighboring countries. By May 1996, Myanmar will have implemented AFP surveillance. Nepal (population 21,918,000). In 1986,2 years before the global polio eradication initiative was adopted, the Government ofnepal intensified its immunization program by implementing the Universal Childhood Immunization (UCI) project. By 1990, coverage for OPV3 among children 1 year of age reached almost 80%; however, coverage has gradually decreased since then. By 1994, reported OPV3 coverage among children 1 year of age in Nepal was 63%, similar to pre-uci levels. Nepal reported 9 cases ofpolio in 1995 and 9 cases in Although Nepal conducts surveillance for AFP, the reported rate per 100,000 children <5 years of age was 0.05 for 1994 (table 1). Of the 9 cases of polio reported in 1995, 6 were culture-confirmed. Three cases were due to wild poliovirus type 1 and 3 to wild poliovirus type 3. Indonesia (population 197,588,000). In 1995, Indonesia reported 12 cases of polio, a 98% decline from the 773 cases reported in Because AFP reporting was not implemented until 1994, estimated reporting rates ofafp through 1994 were low (table 1). In 1993, 17% (4/24) of AFP cases had stool specimens for virologic culture, ofwhich 1 had poliovirus type 1 isolated. By 1995,90% (19/21) had stool specimens collected for virologic culture; 10% (2/21) had 2 stool specimens collected within 2 weeks of paralysis onset. Of the 12 confirmed polio cases, 2 were confirmed because of wild poliovirus type 1 isolation. In September 1995, Indonesia became the third country to conduct NIDs in the Region. Rather than conducting the NIDs on a single day as was done in the Americas and more recently in Thailand and Bangladesh, the Government ofindonesia de-

5 JID 1997; 175 (Supp1 1) Polio Eradication in South-East Asia Region 893 cided to extend the campaign over a week (National Immunization Week). This was considered to be operationally necessary because ofthe nature ofthe dispersed island population (inhabiting ~3000 islands). Preliminary administrative reports indicated that 85% of the nation's children <5 years of age received OPV on the first day of the campaign. ~ Gujarat ~ Karnataka Figure 3. Reported cases of paralytic poliomyelitis, India, Each dot represents 1 reported case. Thailand (population 58,791,000). In 1995, Thailand reported 2 cases of polio, an 82% decline from the 11 cases reported in From 1992 to 1995, AFP reporting rates per 100,000 persons < 15 years old in Thailand were consistently >0.5 (table 1). In 1993, of the 161 AFP cases reported, 94% had stool specimens collected for viral culture. In 1995, of the 118 AFP cases reported, 96% had stool specimens collected. From 1992 to 1995, the percentage of AFP cases with at least 2 stool specimens collected within 2 weeks of paralysis onset increased from 37% in 1992 to 55% in Of the 11 culture-confirmed cases of poliomyelitis reported in 1993, 5 were due to wild poliovirus type 1, 2 were due to wild poliovirus type 2, and 4 were due to wild poliovirus type 3. No vaccine-related polioviruses were reported. In June 1994, 1 culture-confirmed case ofpolio was reported and was associated with wild poliovirus type 1. In 1994, 3 other AFP cases had poliovirus isolates-all vaccine-related (1 each types 1, 2, and 3). In August 1994, Thailand become the first member country in SEAR to conduct NIDs, reaching >95% ofthe 6.8 million children targeted. In 1995, 2 culture-confirmed polio cases were reported. The first occurred in August, just before Thailand's second NIDs, and was due to wild poliovirus type 3. Using molecular techniques similar to those developed for the polio eradication initiative in the Americas [9, 10], the Bangkok VRI polio laboratory did genomic sequencing of the isolate to determine its nucleotide sequence relatedness with other wild polioviruses previously isolated in the area. This analysis revealed that the virus had common ancestral origins with type 3 isolates from India. Since the NIDs in August and September 1995, 1 cultureconfirmed case ofpolio has been reported. The case occurred in November 1995 and was due to wild poliovirus type 1. VRI did a similar analysis of the nucleotide sequence relatedness with other type 1 isolates. This analysis revealed that the virus had common ancestral origins with type 1 isolates from Laos, Cambodia, and Thailand. Although Laos is not a SEAR member country, the VRI in Bangkok provides laboratory services to this neighboring country for virologic surveillance of wild poliovirus. In 1995, VRI reported characterizing 6 polioviruses isolated from specimens sent from Laos with dates of onset ranging from 1992 to One was wild poliovirus type 3 from a Lao case with date of onset in 1992 and the rest were vaccine-related polioviruses (1 each type 1 and type 2 and 3 type 3). Sri Lanka (population 18,354,000). During , Sri Lanka reported no cases of poliomyelitis compared with 16 cases reported in From 1992 to 1995, AFP reporting rates have consistently remained>1.0 per 100,000 persons < 15 years old (table 1). From 1992 to 1995, the percentage of AFP cases with 2 stools collected within 2 weeks ofparalysis onset has dramatically increased, from 27% in 1992 to 94% in The last culture-confirmed case ofpolio occurred in November 1993 and was due to wild poliovirus type 1. From 1994 to

6 S94 Andrus et al. JID 1997;175 (Suppll) 1995, no wild polioviruses were isolated from 157 cases of AFP investigated. In 1994, the only poliovirus isolated was vaccine-related poliovirus type 2. In 1995, Sri Lanka reported characterizing 14 polioviruses, all vaccine-related (4 type 1, 6 type 2, 2 type 3, and 1 mixture of type 1 and type 2). DPR Korea (population 23,917,000). From 1988 to 1994, DPR Korea reported no polio. In 1995, provisional data indicated that 7 cases of polio occurred in DPR Korea. In response, DPR Korea conducted its first NIDs in April and May 1996, achieving >90% coverage. Bhutan (population 1,638,000) and Maldives (population 254,000). Two countries in the Region, Bhutan and Maldives, have not reported cases of poliomyelitis for ~3 years, which suggests that wild poliovirus transmission may have been interrupted. However, in addition to interruption of wild poliovirus transmission for at least 3 years, certification of polio eradication requires criteria indicating adequate surveillance, which has not been implemented in these countries [11]. Discussion During , these data document substantial progress toward polio eradication in SEAR, with an 87% decline in number of reported cases of polio. Bhutan and Maldives have reported zero cases. Data from 1993 to 1995 also indicate that Sri Lanka and Thailand may be close to polio eradication. The last culture-confirmed case of polio reported from Sri Lanka occurred in November After two NIDs, Thailand may have only one remaining reservoir ofwild poliovirus type 1. During , poliovirus infection caused by wild poliovirus type 2 in SEAR was not reported outside of India. By 1995, 6 of 8 countries in which polio is endemic were conducting AFP surveillance compared with 4 of 8 countries in By May 1996, all countries in which polio is endemic, with the exception of DPR Korea, will have implemented AFP surveillance. Both Sri Lanka and Thailand have achieved high AFP reporting rates and percentages of reported AFP cases that have 2 stools taken within 2 weeks ofonset of paralysis for virologic culture. By 1995, the three regional reference laboratories were conducting intratypic differentiation of polioviruses. By 1995, wild poliovirus infection remained highly endemic in 5 SEAR member countries: Bangladesh, India, Indonesia, Myanmar, and Nepal. The subcontinentcountries ofindia, Bangladesh, Nepal, and Myanmar account for 99% of reported cases in SEAR and 56% ofthe reported cases globally. To that end, as recommendedby WHO, NIDs remain a critical strategy in eradicating transmission of wild poliovirus [1, 5]. With the exception of Nepal, 7 of 8 countries in SEAR in which polio is endemic will have conducted NIDs by April At the time of this writing, Nepal planned to conduct its first NIDs in December Of note, on 20 January 1996 (the second round of India's first NIDs), Indian health authorities and volunteers immunized >93 million children with OPY, marking the largest single-day immunization campaign ever. In SEAR, essential strategies for mobilizing resources required for polio eradicationhave been the formation in 1994ofthe Technical Consultative Group on EPI-a group of internationalimmunization experts that meets yearly to review the progress ofdisease control activitiesand providerecommendationsfor improving strategies; the developmentof National Plans of Action for Poliomyelitis Eradication-strategic plans prepared by all member countries that include budget estimates for polio eradication and that are revised annually to reflect progress toward eradication and to assist in overcoming remaining obstacles; and the formation in 1994 of an Interagency Coordination Committee of interested donors-a group that meets periodically to review country plans of action to galvanize financialsupportfrom both governmentaland nongovernmental donor agencies to cover potential shortfalls in resource requirements. Eradication.oftransmission ofwild poliovirus in the Americas was largely accomplished by targeting NIDs in countries in which polio was endemic to children < 5 years old during the low season of transmission [1]. The Pulse Polio Immunization Days scheduled in India targeted all children <3 years old. This decision was based on the experience ofkerala. Data suggest that the target age of <3 years for a polio campaign may work. Also, financial and operational concerns regarding vaccine supply and administration resulted in the selection of a lower age cutoff for the first year of NIDs in India, where the size of one annual birth cohort is -25 million. However, national data suggest that at least 18%-20% of the reported polio cases occur in children ~3 years old. To that end, the target age group will be increased in 1996 NIDs to include children < 5 years old. The major challenges confronting the polio eradication initiative in SEAR include sustaining and expanding coordination of NIDs in all countries in which polio is endemic, ultimately synchronizing NIDs in epidemiologic blocks of countries; strengthening surveillance of AFP and wild poliovirus so that the impactofnids can be evaluated and ultimatelypolio eradication in SEAR can be certified; and using surveillance information to target remaining areas with reservoirs ofwild poliovirus transmission for house-to-house immunization campaigns with OPY. Expanded coordination of NIDs among groups of adjoining countries, such as was done previously in Central America, in the Andean Region of South America, and more recently in the 1995 NID initiative involving 18 countries of Eastern Europe, the Middle East, and central Asia [12], has been a remarkably useful global strategy. Clear-cut advantages to coordinating multicountry NIDs in contiguous epidemiologic blocks include the following: increasing the level ofnational awareness and commitment ofthe political leaders, the general population, and the health personnel, which is further consolidated by the development of a partnership of neighboring nations working toward a common goal (this partnership of nations

7 TID 1997; 175 (Suppll) Polio Eradication in South-East Asia Region S95 has the added benefit of having more global visibility and, perhaps, ofpromoting global peace); achieving greater epidemiologic impact because regional immunization days cover many more endemic areas at the same time, avoiding the risk of reimportation of wild poliovirus from a nonparticipating country to a participating one; increasing the likelihood that otherwise difficult-to-reach migratory populations are fully covered; and making the drive toward polio eradication faster, more efficient, and less costly. Accordingly, SEAR member countries Thailand, Myanmar, Nepal, Bangladesh, and India and Pakistanofthe Eastern Mediterranean Region were planning at this writing to synchronize NIDs in December 1996 and January Bangladesh agrees in principle to participate and has indicated that it will officially endorse this activity soon. In most SEAR member countries, AFP surveillance urgently needs strengthening, particularly since the implementation of NIDs has expanded so rapidly among the countries in which polio is endemic. Underreporting of polio cases is a major concern in countries that have reporting rates for nonpolio AFP of < 1.0 per 100,000 persons < 15 years of age. Experience shows that as AFP reporting improves, improvements in virologic surveillance follow, but usually not nearly to the same degree [1, 13]. One challenge then is to link AFP and wild poliovirus surveillance early in the program so reservoirs of transmission by genotype ofwild poliovirus can be more accurately defined. By integrating surveillance activities early in the eradication program, the gains made by either epidemiologic or virologic surveillance will be mutually beneficial. To date, the expansion ofvirologic services, especially molecular characterization in India, has been impressive; however, virologic surveillance in SEAR generally lags far behind what will be required to eradicate transmission of wild poliovirus. To eradicate polio in Latin America, which has halfthe population ofindia, a network of8 laboratories processed, on average, >6000 stools collected from investigations of AFP patients and their contacts. In comparison, the SEAR Polio Laboratory Network, consisting of 11 laboratories, processed only 1802 specimens in There is a critical need to expand the reporting of AFP cases so that virologic investigations, starting with the collection of stool specimens in the field, can be intensified. Minimal criteria for certification ofpolio eradication in SEAR require that countries demonstrate an AFP reporting rate of at least 1.0 case of AFP per 100,000 persons < 15 years old and, for at least 80% of the reported AFP cases, 2 stool specimens collected within 2 weeks ofparalysis onset for viral culture [11]. Achieving this level of surveillance performance will also allow countries to target specific areas where the remaining reservoirs ofwild poliovirus transmission exist for house-to-house immunization "mop-up" campaigns, as was required in the final stages in the polio eradication initiative of the Americas. Enormous effort will be required to strengthen and maintain surveillance [2, 5]; this is perhaps the greatest challenge [13]. Unless it is done, huge sums of money directed to conducting NIDs will be wasted. Because the majority of global poliomyelitis cases are reported from SEAR, the ability of SEAR member countries to strengthen integrated AFP and virologic surveillance may ultimately determine the success of the global polio eradication initiative. Although recent progress by SEAR member countries has been remarkable, the assessment of the emergence of polio-free countries or of eradication of wild poliovirus may be speculative until adequate surveillance has been developed. Commitment, as reflected by the attitudes of heads of state and agencies, now so amply demonstrated by the implementation of NIDs in several SEAR member countries, must also be directed to the continued development and expansion of integrated AFP and virologic surveillance. To that end, in the first semester of 1996, the Danish Development Agency approved more than $11.5 million (US dollars) and Rotary International is considering $2.7 million to strengthen polio surveillance in India. Other governmental agencies and governments, such as Japanese International Cooperation Agency, the United States Agency for International Development, and Germany, are also demonstrating interest. Efforts to galvanize additional resources in other SEAR countries must be continued. Acknowledgments We acknowledge the national staff of the Ministries of Health of SEAR member countries who have dedicated their lives to sustaining the progress of EPI. The success ofpolio eradication by the year 2000 also depends on a partnership of technical, nontechnical, multilateral, governmental and nongovernmental, and donor agencies. Although most of the total funds for poliomyelitis eradication must be sought in individual countries, international donor support is critical to accomplish the eradication objective. Partners involved in substantially supporting the polio eradication activities include UNICEF, Rotary International, bilateral agencies, such as British Overseas Development Agency, German KFW, Japanese International Cooperation Agency, World Bank, Australian Agency for International Development, United States Agency for International Development, Canadian International Development Agency, Swedish International Development Agency, and the Danish International Development Agency. References 1. World Health Organization. Progress towards poliomyelitis eradication, Wkly Epidemiol Rep 1995;70: de Quadros CA, Andrus JK, Olive lm, de Macedo CG, Henderson DA. Polio eradication from the Western Hemisphere. Annu Rev Public Health 1992; 13: World Health Organization. Expanded Programme on Immunizationprogress towards poliomyelitis eradication, Vietnam. Wkly Epidemiol Rep 1994;69:

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