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THE LAST MILE IN GLOBAL POLIO ERADICATION

Sunday, 23rd of October 2011

• THE LAST MILE IN GLOBAL POLIOMYELITIS ERADICATION

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http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)60744-7/fulltext

The Lancet, Volume 378, Issue 9791, Pages 549 - 552, 13 August 2011

Published Online: 09 June 2011

 

Original Text

Zulfiqar A Bhutta a

Before the development of the inactivated poliovirus vaccine (IPV) in 1955, poliomyelitis paralysed and killed up to half a million people every year. The introduction of the IPV in the USA led to a dramatic reduction in poliomyelitis transmission and cases, from an average 20 000 cases per year in the 1950s to less than 1000 cases by the 1960s.1 With the development of the oral poliovirus vaccine (OPV) and the strategy to give two doses of trivalent OPV to all children younger than 5 years in mass vaccination campaigns, transmission was stopped in the USA by 1979.2 Similar campaigns were launched in many developing countries, notably in Latin America, following an initiative by the Pan American Health Organization to eradicate poliomyelitis in the Americas by 1990. In 1988, the World Health Assembly (WHA), with support and funding from Rotary International, unanimously launched a global goal to eradicate poliomyelitis by 2000.3 Since then the achievements of the Global Poliomyelitis Eradication Initiative, one of the largest global public health programmes, have been remarkable. From a situation in which poliomyelitis was endemic in 125 countries on five continents, paralysing 350 000 children annually, there has been a 99% decrease in the global incidence of the disease,4 with only 20 countries with endemic disease in 2000. One of the three serotypes of wild poliovirus (serotype 2) has been eradicated since 1999.

Despite these impressive initial gains, the last phase of poliomyelitis eradication has been difficult, with uneven progress over the past 5 years (figure). In recognising these trends, WHA called for a new plan to complete the eradication effort and the global eradication strategy was revitalised at its 61st session in May, 2008. Over the past 2 years, transmission of indigenous wild poliovirus types 1 and 3 has continued in geographically limited areas in four countries (Nigeria, India, Pakistan, and Afghanistan), and has also affected countries with low coverage of routine immunisation and weak health systems in central Africa and the horn of Africa.6 Nigeria and India have made enormous gains in the control of poliomyelitis throughout the past year with a more than 90% reduction in cases. Even war-torn Afghanistan has shown a 34% reduction in cases, but Pakistan remains a huge challenge. Inefficiencies within the eradication programme in Pakistan, compounded by recent floods and a smouldering conflict in the north, were associated with a 62% increase in cases, with 144 confirmed children with poliomyelitis in 2010 and over 35 cases in the first quarter of 2011.7 In view of these concerns about slow progress in global eradication, WHO's Director-General established an Independent Monitoring Board of the Global Poliomyelitis Eradication Initiative in 2010. The Board's most recent report (April, 2011)5 presented a mixed picture, noting impressive gains in some parts of the world and residual challenges in others. The overarching theme of the Board and global public health community is continued emphasis on implementation and close monitoring of the current eradication strategy. The Board has rightly underscored several crucial success factors, such as political support, vaccine efficiency, sound surveillance strategies, operational innovations, and demand creation. However, there is a funding gap of US$665 million from the $1·21 billion required for 2010—12.

 

Figure Full-size image (35K) Download to PowerPoint

Global trends in number of cases of poliomyelitis

Adapted from Independent Monitoring Board of the Global Polio Eradication Initiative.5

Notwithstanding the importance of continued focus on staying the course, there are other crucial but neglected issues. Remarkably little public debate about these issues has taken place nationally or globally. Broadly, the issues can be summarised as three challenges which must be met if poliomyelitis is to be eradicated. First, there is a knowledge gap that must be confronted and addressed. Despite the remarkable success of the OPV over time, the current product might not be ideal for the last phase of eradication and for clearing residual pockets of disease. Although impressive seroconversion rates have been reported from many parts of the world,8, 9 the trivalent or monovalent vaccines are not uniformly effective. Of the 144 patients with confirmed poliomyelitis in Pakistan in 2010, 43% had received four or more doses of OPV, suggesting that the vaccine might not be effective in a subset of the population.10 Poor seroconversion after vaccine administration in undernourished children has been reported (Petri W, University of Virginia, VA, USA, personal communication; and my own observations). Although the research needed to develop more effective vaccines and vaccination strategies should not detract from the current global initiative, we need a greater understanding of the vaccine's effectiveness, or lack thereof, in population subsets.

Mucosal immunity induced by the current OPV is imperfect and potentially allows immunised individuals to participate in asymptomatic wild-type poliovirus transmission in settings with efficient faecal-oral transmission of infection. 0·74% of fully vaccinated and asymptomatic children in India continued to excrete wild poliovirus types 1 and 3, and two-thirds of these children had received six or more OPV doses, which is a concern.11 The most recent outbreak of infection, involving 315 cases of type-2 circulating vaccine-derived poliovirus (cVDPV2, >1% divergent from Sabin 2) occurred in Nigeria between July, 2005 and June, 2010, when 23 of 34 supplementary immunisation campaigns used monovalent or bivalent OPV lacking Sabin 2.12 The increased use of serotypes 1 and 3 monovalent OPV might have resulted in improvements in vaccine-induced population immunity against these serotypes, and in declines in immunity to cVDPV2.13 These findings are indicative of the need for control scenarios to take into account the possibility of dealing with virulent vaccine-derived polioviruses at scale, and the potential benefit of including IPV in the eradication strategy in such countries.14 The successful development and use of bivalent OPV is a welcome step for improvement of eradication strategies,15 as are trials of fractionated doses of IPV16 which could make the product more affordable, either singly or in combination with OPV.

Second, are the current strategies for eradication satisfactory? The usual approaches to eradication for the remaining pockets of endemic disease are large-scale national and subnational immunisation days. The evolving epidemiology of poliomyelitis also suggests that population immunity-thresholds needed to interrupt wild-poliovirus transmission differ around the world, and are substantially higher in northern India and parts of Pakistan than in Africa and elsewhere. Although this understanding has led to the systematic development of targeted district-specific and population-specific strategies, and capacity to address heterogeneity in OPV coverage, the mainstay is still a largely vertical strategy for eradication, often distinct from routine expanded programmes for immunisation services. Whereas this separation has not been an issue in countries with strong programmes, in countries where these services are dysfunctional, serious issues of vaccination-programme mismatch are created, affecting overall control.17 For example, of the 144 patients with poliomyelitis in Pakistan in 2010, 67% were younger than 2 years and 68% had not received any routine immunisation.10 This finding is indicative of the difficulty of trying to eradicate poliomyelitis through a parallel programme delinked from routine expanded services. This approach is possible, but is fraught with the risk of failure. Integration of eradication strategies and routine immunisation services should be possible, because the inequity of resources, manpower, and surveillance systems for both programmes is a serious limitation for control and eradication of the disease. The risk of reintroduction of poliomyelitis into countries now free from the disease is compounded by poor overall immunisation rates, as in parts of Africa, Pakistan, and Tajikistan. Programme managers vehemently deny the lack of integration between poliomyelitis and expanded programmes for immunisation, but the reality on the ground suggests otherwise. Huge differentials exist between the two programmes for overall support services, financial resources, staff incentives for performance, and surveillance methods. WHO's recent decision to separate the poliomyelitis programme from the mainstream vaccination cluster also sends the wrong message when there is much need to focus on integration rather than fragmentation.

Finally, community engagement and creation of grass-roots support for poliomyelitis eradication is key, and related to the issues already mentioned. Without adequate demand-creation, and understanding barriers and addressing them systematically, approaching populations in the same way as before is naive. In many parts of urban and rural Pakistan (and possibly elsewhere), the only vaccination service that people are aware of and access is the poliomyelitis programme; and with home delivery of OPV, incentivising people to seek routine immunisations in expanded programmes is a challenge. The recognition that a substantial proportion of residual disease (both from wild viruses and cVDPV) is in children who have received multiple doses of OPV is a source of disquiet from communities. In these circumstances innovative strategies that couple OPV and IPV could be a way forward.

All these issues should not detract from the importance of staying on track in the final phase of the global strategy for poliomyelitis eradication. However, without adequately addressing some of the real barriers to eradication and creation of innovative solutions to tackle emerging issues, the risk of failure is high. Although we agree with the sentiments of Stephen Cochi, from the US Centers for Disease Control and Prevention, that “to stop now would be snatching defeat from the jaws of victory,”18 victory is by no means assured. All resources and collective wisdom should be combined to ensure that the last mile in the race to eradicate poliomyelitis is the very last mile that we ever run in the quest to relegate poliomyelitis to the corridors of history. 

 

My institution has grants from WHO to measure poliomyelitis seroprevalence in Pakistan and to assess nutrition interventions and poliomyelitis response. I am also a member of WHO's Strategic Advisory Committee for Vaccines, and the Regional Techincal Advisory Group for Polio for WHO Regional Office for the Eastern Medditerranean. The views in this Comment are my own.

1 Salk D. Eradication of poliomyelitis in the United States II: experience with killed poliovirus vaccine. Rev Infect Dis 1980; 2: 243-257. PubMed

2 Sabin AB. Perspectives on current use of some virus vaccines in the USA. Measles, rubella, poliomyelitis, and influenza in the USA: contrasts in control by vaccination. Pediatr Res 1979; 13: 674-683. CrossRef | PubMed

3 World Health Assembly. Global eradication of poliomyelitis by the year 2000. http://www.polioeradication.org/Portals/0/Document/AboutUs/History/WHA.Resolutions.and.Decisions.pdf. (accessed May 16, 2011).

4 Global Polio Eradication Initiative. Progress. http://www.polioeradication.org/Aboutus/Progress.aspx. (accessed May 16, 2011).

5 Independent Monitoring Board of the Global Polio Eradication Initiative. Report. http://www.polioeradication.org/Portals/0/Document/Data&Monitoring/IMB_Reports/IMB_Report_April.pdf. (accessed May 16, 2011).

6 Centers for Disease Control and Prevention (CDC). Wild poliovirus type 1 and type 3 importations—15 countries, Africa, 2008—2009. MMWR Morb Mortal Wkly Rep 2009; 58: 357-362. PubMed

7 Global Polio Eradication Initiative. Polio this week—as of Wednesday 11 May 2011. http://www.polioeradication.org/Dataandmonitoring/Poliothisweek.aspx. (accessed May 16, 2011).

8 El-Sayed N, Al-Jorf S, Hennessey KA, et al. Survey of poliovirus antibodies during the final stage of polio eradication in Egypt. Vaccine 2007; 25: 5062-5070. CrossRef | PubMed

9 Hasan AS, Malik A, Shukla I, Malik MA. Antibody levels against polioviruses in children following Pulse Polio Immunization Program. Indian Pediatr 2004; 41: 1040-1044. PubMed

10 National Surveillance and Campaign CellFederal EPI. In: National polio eradication bulletin, January, 2011: issue 01. Islamabad: Ministry of Health, Government of Pakistan, 2011: 1-14.

11 Grassly NC, Jafari H, Bahl S, et al. Asymptomatic wild-type poliovirus infection in India among children with previous oral poliovirus vaccination. J Infect Dis 2010; 201: 1535-1543. CrossRef | PubMed

12 Wassilak S, Pate MA, Wannemuehler K, et al. Outbreak of type 2 vaccine-derived poliovirus in Nigeria: emergence and widespread circulation in an underimmunized population. J Infect Dis 2011; 203: 898-909. CrossRef | PubMed

13 Jenkins HE, Aylward RB, Gasasira A, et al. Implications of a circulating vaccine-derived poliovirus in Nigeria. N Engl J Med 2010; 362: 2360-2369. CrossRef | PubMed

14 Grassly NC, Jafari H, Bahl S, et al. Mucosal immunity after vaccination with monovalent and trivalent oral poliovirus vaccine in India. J Infect Dis 2009; 200: 794-801. CrossRef | PubMed

15 Sutter RW, John TJ, Jain H, et al. Immunogenicity of bivalent types 1 and 3 oral poliovirus vaccine: a randomised, double-blind, controlled trial. Lancet 2010; 376: 1682-1688. Summary | Full Text | PDF(299KB) | CrossRef | PubMed

16 Mohammed AJ, AlAwaidy S, Bawikar S, et al. Fractional doses of inactivated poliovirus vaccine in Oman. N Engl J Med 2010; 362: 2351-2359. CrossRef | PubMed

17 Bonu S, Rani M, Baker TD. The impact of the national polio immunization campaign on levels and equity in immunization coverage: evidence from rural North India. Soc Sci Med 2003; 57: 1807-1819. CrossRef | PubMed

18 McKenna MAJ. Polio eradication is impossible, doctors told, angry CDC experts disagree. The Atlanta Journal and Constitution. http://www.marynmckenna.com/newspapers_files/polio102702.pdf. (accessed May 18, 2011).

a Division of Women and Child Health, Aga Khan University, Karachi 74800, Pakistan

 

• MALARIA IN AFRICA CAN BE ELIMINATED

 

1. 1.   Carlos C. Campbell* and
2. 2.   Richard W. Steketee 

+ Author Affiliations

1. 1.    Malaria Control Program, PATH, Seattle, Washington

+ Author Notes

       Authors' addresses: Carlos C. Campbell and Richard W. Steketee, Malaria Control Program, PATH, Seattle, WA, E-mails: cccampbell@path.org and rsteketee@path.org.

1. ↵*Address correspondence to Carlos C. Campbell, Malaria Control Program, PATH, PO Box 900922, Seattle, WA 98109. E-mail: cccampbell@path.org

Also at http://www.ajtmh.org/content/85/4/584.full

 

Abstract

A concerted effort to control malaria in Africa has produced dramatic reductions in childhood death in the past decade. This early success has prompted the global community to commit to eradication of malaria deaths and eventually all transmission. Evidence suggests that this is a feasible goal using currently available interventions, augmented with newer tools such as vaccines, which are in development. Malaria deaths are entirely preventable now, and our sustained political and financial commitment to continue to prevent these deaths hangs in the balance.

We are witnessing major successes in fighting malaria—a disease that, until recently, killed over 1 million people each year, mainly African children. The accomplishments have been impressive. The scale up for impact (SUFI) strategy—rapidly delivering malaria prevention interventions to achieve coverage of most or all at-risk populations—has been endorsed by the global Roll Back Malaria (RBM) Partnership,1 and has become the national malaria control standard in the Africa region. An increasing number of African countries, led by their national malaria partnerships, are distributing millions of long-lasting insecticide-treated mosquito nets (LLINs), spraying household walls with insecticides, and rolling out new diagnostics and effective medicines nationwide to strengthen the management of malaria infections. The package of interventions, especially the LLINs, has proven to be a powerful arsenal capable of saving many lives. Many countries have recently documented a fall in childhood deaths in the range of 20–25%, and it is estimated that more than 1 million African children are alive today that otherwise would have died of malaria2; however, it is too early to celebrate.

This dramatic success has created what will become the generational challenge for malaria control. Scale-up campaigns have jump-started malaria control, bringing down malaria transmission to levels where deaths are largely prevented and malaria is no longer a pervasive drain on health services. Although as malaria declines, so may commitment to fight the disease. With the malaria problem seemingly “solved,” national governments and funding agencies can easily turn their focus—and wallets—to other pressing health priorities.

As SUFI was becoming the rallying cry for national malaria programs, eradication was placed back on the global agenda as a long-term vision in 2007 (Gates Foundation Malaria Forum, October 2007, Seattle WA). The memory of the earlier Malaria Eradication Program of the 1950s and 60s3 was invoked—both its successes (malaria elimination was certified in many countries) and its failures (elimination faltered because of heavy reliance on indoor insecticide spraying and evolving insecticide resistance resulting in malaria resurgence in many areas). The call for eradication sparked some skepticism initially, but has overall generated enthusiasm and commitment. The RBM Global Malaria Action Plan (GMAP) charted the pathway from scale up to elimination. The World Health Organization (WHO)4 and the Malaria Elimination Group5 described approaches to elimination. And, with the suggestion that new and better tools would be required, the Malaria Eradication Research Agenda (malERA) Group6 detailed the research agenda to generate new tools and strategies.

The complex challenges ahead to fully eliminate malaria from Africa are becoming clearer. Although the GMAP embraced both SUFI and elimination, the middle ground— termed “sustained control”—highlighted the need for continued work to preserve the progress in achieving high coverage but did not address how a national program could actually transition to elimination. Unfortunately, this means that the malaria control community and the many countries that have experienced marked progress do not have clarity or consensus, on the next steps.

We suggest that there are discrete steps on the path between scale up and elimination and that, in most places, these steps can be taken using existing control methods (LLINs, indoor residual spraying, diagnostics and effective antimalarial medicines). Adaptation of these tools, guided by a focused strategy that continuously evolves to address the dynamic challenges of reducing malaria transmission, can ultimately result in countries achieving zero transmission. Zero malaria transmission would mean a true end to the plague of malaria illness and death.

The first step is to finish the scale-up work. Despite huge efforts, the current malaria control strategies have not yet been deployed to fully cover the populations at risk. And, because the child who was protected under an LLIN last night must sleep under one each successive night, the culture of malaria prevention must become part of the fabric of life in every community.

The second step is to gain efficiencies in delivering the preventive and case management components of the strategy. This step includes strengthened management and supply chain systems that make it easier to anticipate and fill program gaps in a timely manner or before they actually become gaps—focusing on human resource needs, commodity supplies, and local data to guide program implementation. This work both ensures full scale up and optimizes the use of available resources.

The third step is to further reduce malaria transmission. The program gains that have been achieved with the implementation of SUFI have resulted in a major (~10-fold) reduction in malaria transmission intensity7; in many areas, remaining levels of transmission are still too high and must be brought down another 10-fold or more to reach levels that fulfill pre-elimination or elimination criteria. Because the first transmission reductions were largely accomplished through killing mosquitoes, the remaining parasites mostly reside in people. Clearing these infections requires strategies to systematically find and kill parasites in the human population. This is not simply an improved management of symptomatic infections because many infected (and transmitting) people are asymptomatic; to further reduce transmission, we must find and cure all infected people.

Clearing all malaria infections is only possible with access to real-time data on where the residual infections are today and in the future. All countries striving for elimination will need to know when elimination has occurred and will need surveillance, diagnostic capability, and monitoring and evaluation systems that have sufficient reach and quality to provide that information in real time.

There is accumulating program experience in a diverse range of African countries suggesting that maintaining high LLIN usage combined with aggressive malaria infection detection and drug treatment to completely kill off all detected malaria infections can break the chain of malaria transmission in communities.8 This approach is currently being tested in national programs in a number of African nations; soon these efforts will generate solid evidence on the extent to which it is effective in eliminating malaria deaths and reducing transmission.

Experience from decades past has taught that the path to elimination has identifiable steps, but the progression is not entirely predictable across all countries. Attempts at eradicating malaria in the mid-1960s were rapidly successful in many countries, but progress was much slower and more complex in other areas, and the effort was eventually abandoned. Donor fatigue led to a loss of funding and commitment to control malaria. The recipe for success this time must include community involvement and ownership, local and national willingness (including growing domestic funding) to persevere until the task is complete, and unwavering global support. We must embrace this as a learning process that will require adaptive science to achieve elimination.

It has been suggested that malaria elimination is too ambitious a goal, impossible to achieve with current interventions and available financing, and that we must wait for some future tool—such as a vaccine that blocks malaria transmission—to aspire to stopping transmission. Alternative goals have been suggested; for example, to attempt to maintain malaria transmission at low levels whereby malaria deaths are few but the program costs are recurrent with no definable end point. Some have even suggested that Africa should just live with some level of malaria, as if that is not what Africa has been forced to do for time in memoriam.

Malaria control remains one of the best investments in global health: malaria deaths can be eliminated now with currently available interventions. We have vastly more powerful tools than ever before, we have comprehensive methods of collecting data to inform our work, and national governments are leading the charge, leveraging external assistance to dramatically reduce malaria illnesses and deaths. New and potentially more powerful interventions such as malaria vaccines will be available in the foreseeable future. However, we must refuse to let history repeat itself.

We must reach beyond the relatively easy successes of SUFI to address the next steps for malaria control in Africa; our shared ambition must be elimination not only of deaths but the permanent end of transmission. This will require sustaining and even increasing the unprecedented financial resources invested in the last decade,9 despite competing health priorities, and committing to the challenge until the job is done. Mothers and their children throughout Africa deserve our assurance that we will not settle for less.

       Received August 12, 2011.

       Accepted August 15, 2011.

       ©The American Society of Tropical Medicine and Hygiene

 

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