JECH Online First, published on June 3, 2015 as 10.1136/jech-2015-205529
Current goals and prospects of the global polio eradication initiative James Ayukepi Ayukekbong There is nothing to be gained by saying that the Global Polio Eradication Initiative (GPEI) has made tremendous progress since its commitment, in 1988, to eradicate polio.1 There has been a reduction in the incidence of poliomyelitis by more than 99% and the number of countries that have never interrupted wild poliovirus (WPV) transmission has reduced from an estimated 125 countries to 3 countries (Afghanistan, Nigeria and Pakistan).1 In 1999, the GPEI announced the eradication of WPV type 2,2 and the most recent case due to WPV type 3 was reported after November 2012 in Nigeria. However, WPV type 1 and circulating vaccine-derived polioviruses (cVDPVs) continue to spread in endemic countries and be imported to previously polio-free countries.3 Although global polio eradication has been delayed by 15 years past the original target date set for the year 2000, the eradication is considered feasible by the GPEI based on the success achieved so far.4 However, the GPEI is faced with a chain of challenges to free the world from the last 1% of WPV and VDPV transmission. The main difficulties in stemming polio transmission in the three endemic countries are peculiar; successful eradication depends on an in-depth understanding of specific factors hindering polio vaccination campaigns in these countries. Lack of trust, political instability, violence and militancy are the main factors that threaten polio eradication efforts in all three countries.5 Some areas of these countries have yet to consider polio a priority amidst other health problems such as malnutrition, lack of potable water supply and poverty, as well as a host of childhood killer diseases (eg, malaria, pneumonia and diarrhoea). Polio eradication has, therefore, in these countries, been considered as influenced by the West, since basic local health problems have been neglected and more interest placed on polio, a global health problem. This has unfortunately led some terrorist groups to believe that they can stage an anti-West attack by interfering with polio eradication. They also suspect that the Correspondence to Dr James Ayukekbong, Section for Clinical Research, Redeem Biomedical System, Buea, Cameroon; [email protected]
vaccination workers are acting as spies and that polio surveillance is an indirect activity to identify wanted persons (as was the case when the USA used a fake hepatitis B vaccination campaign to track down Osama bin Laden).6 To mitigate this problem, there should be active engagement of community institutions, such as the involvement of traditional, religious and political leaders to dispel myths about polio vaccines and to disseminate information on the importance of the vaccination so that the disease may be seen as a health problem rather than part of a foreign agenda. This will likely improve vaccine acceptability at the grass roots level.7 Polio vaccination campaigns should also be embedded within other childhood immunisation programmes such as those for pneumonia, rotavirus, tuberculosis, yellow fever and measles. This strategy will deviate the focus on polio and will likely reduce the chances of rejection. The recent waves of fatal attacks on polio vaccination workers in these three countries have often disrupted routine immunisation programmes, resulting in pockets of unimmunised children in some conflict prone regions.8 9 Trust, vaccine acceptance, education and security are therefore indispensable for polio eradication in these regions. All countries in the world remain at risk for importation as long as circulation continues in these countries. To achieve global eradication, there is a need for political commitment and regional stability to provide a conducive environment for immunisation, polio surveillance and to establish measures to minimise the risk of importation of WPV or VDPV into other regions. Global eradication efforts have relied on effective immunisation using a live, attenuated, oral poliovirus vaccine (OPV) that is inexpensive and easy to administer. The vaccine provides long-term protection through durable gut and humoral immunity.10 Unfortunately, rare cases of VDPV can emerge following sustained circulation in populations with immunity gaps.11 OPV vaccinees shed vaccine derived viruses in their faeces, causing a mass inundation of excreted viruses into the environment after mass OPV vaccination campaigns.12 In rare instances, OPV use can cause vaccine-associated paralytic
Editorial
poliomyelitis. As a result, once WPV eradication has been verified globally, the attenuated Sabin poliovirus strains used in OPV (VDPV) could continue to cause polio outbreak at an unpredictable rate. Therefore, the use of OPV post interruption of transmission of WPV is deemed inconsistent with eradication. An obvious long-term challenge of the use of OPV to global polio eradication is the chronic infection of immunodeficient persons with VDPVs, who are referred to as immunodeficient VDPV (iVDPVs). The risks of long-term persistent infections have been reported among persons with primary B-cell immunodeficiencies.13 An example is a person with common variable immunodeficiency with a history of excreting iVDPVs for about 20 years.13 With the extended shedding of VDPV, it is necessary that environmental surveillance of poliovirus be continue even in the postpolio eradication era due to risks of infection when immunity wanes out. Previous polio surveillance recommended by WHO depended on the detection and investigation of cases of acute flaccid paralysis (AFP) by viral isolation from two faecal samples from a patient and/or sometimes from close contacts.10 The limitation of this approach is that it detected polioviruses only in those presenting with polio-associated symptoms. In essence, this approach could be viewed as diagnostic rather than being preventive. To attain the polio eradication endgame strategic plan 2013–2018, implemented by GPEI for the worldwide interruption of transmission of WPV, environmental polio surveillance has been recommended to supplement routine AFP surveillance.10 The goal of this plan is the eradication of all polio disease, whether caused by WPV or cVDPV, as the detection of WPV in sewage in a community reflects the presence of virus-shedding individuals who may be asymptomatic or those with acute flaccid paralysis. It is, therefore, necessary to determine where, how and which poliovirus is still circulating, and to ultimately verify eradication of the virus. Taking into account that for each case of paralytic polio detected, there are about 200 asymptomatic polio shedders in the population,1 environmental sewage surveillance is an attractive approach for the GPEI endgame. Unfortunately, environmental surveillance of poliovirus in polioprone developing countries is challenging, as an inadequate sewer network poses a major challenge for identifying representative sampling sites. Also, as already mentioned, most of the polio endemic countries suffer from political instability
Ayukekbong JA. J Epidemiol Community Health Month 2015 Vol 0 No 0
Copyright Article author (or their employer) 2015. Produced by BMJ Publishing Group Ltd under licence.
1
Editorial and terrorism posing security risks for field staff. Finally, a fundamental issue that the GPEI needs to consider is that eradication should imply the extinction of the virus and not just the absence of polio cases. There have been cases of WPV being detected in environmental samples even from countries where polio is considered eradicated.14 Therefore, in concrete terms, eradication means that the virus and not just the disease must be extinct. To achieve this, once the disease is considered eradicated, the next step will be to modify immunisation programmes safely so that poliomyelitis does not re-emerge. It has been proposed that there should be a coordinated switch from OPV to IPV use and eradication should be declared only after 3 years from the detection of the last WPV, followed by effective containment of laboratory and production strains.15 Even when poliovirus is eradicated, there would be a need for highquality immunisation programmes to be maintained indefinitely. Together, efforts over the past 27 years suggest that there have been significant gains in the global commitment to eradicate polio. The lesson of the recent detection of polio in sewage in Israel (a country declared polio-free since 1988) is a consequence of failure to eradicate polio in the source reservoir, Pakistan, and suggests that the risk of re-emergence of polio is real and that any country is vulnerable
2
to re-importation or re-emergence of poliovirus. Therefore, the best defence against poliovirus is a good offence that eliminates the virus from the remaining reservoirs, and biocontainment measures to prevent the reintroduction of wild virus from laboratory stocks. Unfortunately, the year 2018 envisaged by the GPEI seems too close for this to be attained. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
4 5
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8
Competing interests The author is a consultant in enteric virus epidemiology to public health, Cameroon. Provenance and peer review Commissioned; externally peer reviewed. To cite Ayukekbong JA. J Epidemiol Community Health Published Online First: [ please include Day Month Year] doi:10.1136/jech-2015-205529 Received 1 April 2015 Revised 20 May 2015 Accepted 21 May 2015
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J Epidemiol Community Health 2015;0:1–2. doi:10.1136/jech-2015-205529 13
REFERENCES 1
2
3
Moturi EK, Porter KA, Wassilak SGF, et al. Progress towards polio eradication—worldwide, 2013–2014. MMWR 2014;63:368–72. Centers for Disease Control and Prevention CDC. Progress toward the global interruption of wild poliovirus type 2 transmission, 1999. MMWR Morb Mortal Wkly Rep 1999;48:736–8. Jenkins HE, Aylward RB, Gasasira A, et al. Implications of a circulating vaccine-derived poliovirus in Nigeria. N Engl J Med 2010;362:360–2369.
14
15
Ayukekbong JA, Bergstrom T. Polio will go, acute flaccid paralysis will stay. Lancet 2014;383:2209–10. Abimbola S, Malik AU, Mansoor GF. The final push for polio eradication: addressing the challenge of violence in Afghanistan, Pakistan, and Nigeria. PLoS Med 2013;10:e1001529. Scientific American (2013) How the CIA’s fake vaccination campaign endangers us all. http://www. scientificamerican.com/article.cfm?id=how-cia-fakevaccination-campaign-endangers-us-all (accessed 18 May 2015) Abimbola S. Integration, community engagement, and polio eradication in Nigeria. Lancet Glob Health 2014;2:e315. Khan T, Qazi J. Hurdles to the global antipolio campaign in Pakistan: an outline of the current status and future prospects to achieve a polio free world. J Epidemiol Community Health 2013;67:696–702. Hussain SA, Nagaraja SB, Menezes RG. Military intervention: the last option for polio eradication in Pakistan? J Infect Public Health 2015. Grassly N. The final stages of the global eradication of poliomyelitis. Phil Trans R Soc B 2013;368:1–10. Minor P. Vaccine-derived poliovirus (VDPV): impact on poliomyelitis eradication. Vaccine 2009;27: 2649–52. Poyry T, Stenvik M, Hovi T. Viruses in sewage waters during and after a poliomyelitis outbreak and subsequent nationwide oral poliovirus vaccination campaign in Finland. Appl Environ Microbiol 1988;54:371–4. MacLennan C, Dunn G, Huissoon AP, et al. Failure to clear persistent vaccine-derived neurovirulent poliovirus infection in an immunodeficient man. Lancet 2004;363:1509–13. Kopel E, Kaliner E, Grotto I. Lessons from a public health emergency—importation of wild poliovirus to Israel. N Engl J Med 2014;371:981–3. Dowdle WR, Wolff C. Post-eradication poliovirus facility-associated community risks. Biologicals 2006;34:127–32.
Ayukekbong JA. J Epidemiol Community Health Month 2015 Vol 0 No 0
Current goals and prospects of the global polio eradication initiative James Ayukepi Ayukekbong There is nothing to be gained by saying that the Global Polio Eradication Initiative (GPEI) has made tremendous progress since its commitment, in 1988, to eradicate polio.1 There has been a reduction in the incidence of poliomyelitis by more than 99% and the number of countries that have never interrupted wild poliovirus (WPV) transmission has reduced from an estimated 125 countries to 3 countries (Afghanistan, Nigeria and Pakistan).1 In 1999, the GPEI announced the eradication of WPV type 2,2 and the most recent case due to WPV type 3 was reported after November 2012 in Nigeria. However, WPV type 1 and circulating vaccine-derived polioviruses (cVDPVs) continue to spread in endemic countries and be imported to previously polio-free countries.3 Although global polio eradication has been delayed by 15 years past the original target date set for the year 2000, the eradication is considered feasible by the GPEI based on the success achieved so far.4 However, the GPEI is faced with a chain of challenges to free the world from the last 1% of WPV and VDPV transmission. The main difficulties in stemming polio transmission in the three endemic countries are peculiar; successful eradication depends on an in-depth understanding of specific factors hindering polio vaccination campaigns in these countries. Lack of trust, political instability, violence and militancy are the main factors that threaten polio eradication efforts in all three countries.5 Some areas of these countries have yet to consider polio a priority amidst other health problems such as malnutrition, lack of potable water supply and poverty, as well as a host of childhood killer diseases (eg, malaria, pneumonia and diarrhoea). Polio eradication has, therefore, in these countries, been considered as influenced by the West, since basic local health problems have been neglected and more interest placed on polio, a global health problem. This has unfortunately led some terrorist groups to believe that they can stage an anti-West attack by interfering with polio eradication. They also suspect that the Correspondence to Dr James Ayukekbong, Section for Clinical Research, Redeem Biomedical System, Buea, Cameroon; [email protected]
vaccination workers are acting as spies and that polio surveillance is an indirect activity to identify wanted persons (as was the case when the USA used a fake hepatitis B vaccination campaign to track down Osama bin Laden).6 To mitigate this problem, there should be active engagement of community institutions, such as the involvement of traditional, religious and political leaders to dispel myths about polio vaccines and to disseminate information on the importance of the vaccination so that the disease may be seen as a health problem rather than part of a foreign agenda. This will likely improve vaccine acceptability at the grass roots level.7 Polio vaccination campaigns should also be embedded within other childhood immunisation programmes such as those for pneumonia, rotavirus, tuberculosis, yellow fever and measles. This strategy will deviate the focus on polio and will likely reduce the chances of rejection. The recent waves of fatal attacks on polio vaccination workers in these three countries have often disrupted routine immunisation programmes, resulting in pockets of unimmunised children in some conflict prone regions.8 9 Trust, vaccine acceptance, education and security are therefore indispensable for polio eradication in these regions. All countries in the world remain at risk for importation as long as circulation continues in these countries. To achieve global eradication, there is a need for political commitment and regional stability to provide a conducive environment for immunisation, polio surveillance and to establish measures to minimise the risk of importation of WPV or VDPV into other regions. Global eradication efforts have relied on effective immunisation using a live, attenuated, oral poliovirus vaccine (OPV) that is inexpensive and easy to administer. The vaccine provides long-term protection through durable gut and humoral immunity.10 Unfortunately, rare cases of VDPV can emerge following sustained circulation in populations with immunity gaps.11 OPV vaccinees shed vaccine derived viruses in their faeces, causing a mass inundation of excreted viruses into the environment after mass OPV vaccination campaigns.12 In rare instances, OPV use can cause vaccine-associated paralytic
Editorial
poliomyelitis. As a result, once WPV eradication has been verified globally, the attenuated Sabin poliovirus strains used in OPV (VDPV) could continue to cause polio outbreak at an unpredictable rate. Therefore, the use of OPV post interruption of transmission of WPV is deemed inconsistent with eradication. An obvious long-term challenge of the use of OPV to global polio eradication is the chronic infection of immunodeficient persons with VDPVs, who are referred to as immunodeficient VDPV (iVDPVs). The risks of long-term persistent infections have been reported among persons with primary B-cell immunodeficiencies.13 An example is a person with common variable immunodeficiency with a history of excreting iVDPVs for about 20 years.13 With the extended shedding of VDPV, it is necessary that environmental surveillance of poliovirus be continue even in the postpolio eradication era due to risks of infection when immunity wanes out. Previous polio surveillance recommended by WHO depended on the detection and investigation of cases of acute flaccid paralysis (AFP) by viral isolation from two faecal samples from a patient and/or sometimes from close contacts.10 The limitation of this approach is that it detected polioviruses only in those presenting with polio-associated symptoms. In essence, this approach could be viewed as diagnostic rather than being preventive. To attain the polio eradication endgame strategic plan 2013–2018, implemented by GPEI for the worldwide interruption of transmission of WPV, environmental polio surveillance has been recommended to supplement routine AFP surveillance.10 The goal of this plan is the eradication of all polio disease, whether caused by WPV or cVDPV, as the detection of WPV in sewage in a community reflects the presence of virus-shedding individuals who may be asymptomatic or those with acute flaccid paralysis. It is, therefore, necessary to determine where, how and which poliovirus is still circulating, and to ultimately verify eradication of the virus. Taking into account that for each case of paralytic polio detected, there are about 200 asymptomatic polio shedders in the population,1 environmental sewage surveillance is an attractive approach for the GPEI endgame. Unfortunately, environmental surveillance of poliovirus in polioprone developing countries is challenging, as an inadequate sewer network poses a major challenge for identifying representative sampling sites. Also, as already mentioned, most of the polio endemic countries suffer from political instability
Ayukekbong JA. J Epidemiol Community Health Month 2015 Vol 0 No 0
Copyright Article author (or their employer) 2015. Produced by BMJ Publishing Group Ltd under licence.
1
Editorial and terrorism posing security risks for field staff. Finally, a fundamental issue that the GPEI needs to consider is that eradication should imply the extinction of the virus and not just the absence of polio cases. There have been cases of WPV being detected in environmental samples even from countries where polio is considered eradicated.14 Therefore, in concrete terms, eradication means that the virus and not just the disease must be extinct. To achieve this, once the disease is considered eradicated, the next step will be to modify immunisation programmes safely so that poliomyelitis does not re-emerge. It has been proposed that there should be a coordinated switch from OPV to IPV use and eradication should be declared only after 3 years from the detection of the last WPV, followed by effective containment of laboratory and production strains.15 Even when poliovirus is eradicated, there would be a need for highquality immunisation programmes to be maintained indefinitely. Together, efforts over the past 27 years suggest that there have been significant gains in the global commitment to eradicate polio. The lesson of the recent detection of polio in sewage in Israel (a country declared polio-free since 1988) is a consequence of failure to eradicate polio in the source reservoir, Pakistan, and suggests that the risk of re-emergence of polio is real and that any country is vulnerable
2
to re-importation or re-emergence of poliovirus. Therefore, the best defence against poliovirus is a good offence that eliminates the virus from the remaining reservoirs, and biocontainment measures to prevent the reintroduction of wild virus from laboratory stocks. Unfortunately, the year 2018 envisaged by the GPEI seems too close for this to be attained. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
4 5
6
7
8
Competing interests The author is a consultant in enteric virus epidemiology to public health, Cameroon. Provenance and peer review Commissioned; externally peer reviewed. To cite Ayukekbong JA. J Epidemiol Community Health Published Online First: [ please include Day Month Year] doi:10.1136/jech-2015-205529 Received 1 April 2015 Revised 20 May 2015 Accepted 21 May 2015
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J Epidemiol Community Health 2015;0:1–2. doi:10.1136/jech-2015-205529 13
REFERENCES 1
2
3
Moturi EK, Porter KA, Wassilak SGF, et al. Progress towards polio eradication—worldwide, 2013–2014. MMWR 2014;63:368–72. Centers for Disease Control and Prevention CDC. Progress toward the global interruption of wild poliovirus type 2 transmission, 1999. MMWR Morb Mortal Wkly Rep 1999;48:736–8. Jenkins HE, Aylward RB, Gasasira A, et al. Implications of a circulating vaccine-derived poliovirus in Nigeria. N Engl J Med 2010;362:360–2369.
14
15
Ayukekbong JA, Bergstrom T. Polio will go, acute flaccid paralysis will stay. Lancet 2014;383:2209–10. Abimbola S, Malik AU, Mansoor GF. The final push for polio eradication: addressing the challenge of violence in Afghanistan, Pakistan, and Nigeria. PLoS Med 2013;10:e1001529. Scientific American (2013) How the CIA’s fake vaccination campaign endangers us all. http://www. scientificamerican.com/article.cfm?id=how-cia-fakevaccination-campaign-endangers-us-all (accessed 18 May 2015) Abimbola S. Integration, community engagement, and polio eradication in Nigeria. Lancet Glob Health 2014;2:e315. Khan T, Qazi J. Hurdles to the global antipolio campaign in Pakistan: an outline of the current status and future prospects to achieve a polio free world. J Epidemiol Community Health 2013;67:696–702. Hussain SA, Nagaraja SB, Menezes RG. Military intervention: the last option for polio eradication in Pakistan? J Infect Public Health 2015. Grassly N. The final stages of the global eradication of poliomyelitis. Phil Trans R Soc B 2013;368:1–10. Minor P. Vaccine-derived poliovirus (VDPV): impact on poliomyelitis eradication. Vaccine 2009;27: 2649–52. Poyry T, Stenvik M, Hovi T. Viruses in sewage waters during and after a poliomyelitis outbreak and subsequent nationwide oral poliovirus vaccination campaign in Finland. Appl Environ Microbiol 1988;54:371–4. MacLennan C, Dunn G, Huissoon AP, et al. Failure to clear persistent vaccine-derived neurovirulent poliovirus infection in an immunodeficient man. Lancet 2004;363:1509–13. Kopel E, Kaliner E, Grotto I. Lessons from a public health emergency—importation of wild poliovirus to Israel. N Engl J Med 2014;371:981–3. Dowdle WR, Wolff C. Post-eradication poliovirus facility-associated community risks. Biologicals 2006;34:127–32.
Ayukekbong JA. J Epidemiol Community Health Month 2015 Vol 0 No 0
