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Polio eradication effort sees progress, but problems remain

2014; Elsevier BV; Volume: 383; Issue: 9921 Linguagem: Inglês

10.1016/s0140-6736(14)60452-9

1474-547X

John Maurice,

Global Public Health Policies and Epidemiology

WHO looks set to declare its southeast Asia region polio-free at the end of this month. But progress is faltering in other regions with the remaining polio-endemic countries. John Maurice reports. If a country's population could give a sigh of relief, the sound from India on Jan 13, 2014, would have been deafening. On that day, India celebrated 3 years without a single case of polio caused by the wild polio virus, thereby meeting WHO's criterion for polio-free certification and becoming the last of the 11 countries of WHO's South-East Asia Region to do so. On March 27, 2014, a meeting in New Delhi of the regional Certification Commission is expected to declare polio officially eradicated from the entire region, which will then join the three other polio-free WHO regions—of the Americas, Western Pacific, and Europe—leaving Africa and the Eastern Mediterranean to finish the job and cast the poliovirus into the same chapter of history as the smallpox virus. Many polio watchers were amazed at India's achievement. “Nearly everybody regarded India as a country impossible to rid itself of polio”, says Carol Pandak, who heads the PolioPlus project of Rotary International, a major partner in the Global Polio Eradication Initiative (GPEI) and a powerful grassroots participant in India's anti-polio drive. “Just think, when the eradication initiative began in 1988, there were 350 000 new cases of polio every year in 125 countries and just one of those countries, India, accounted for about half of those cases. Just think, too, of the huge population of India, of its large migrant groups on the move from one place to another, of the poor sanitary conditions in so many places, and of the geographical and social barriers to finding and reaching children to be vaccinated. At one point, we really wondered if it would be possible to complete the job.” Margaret Chan, WHO Director-General, was also impressed: “India has shown the world that there is no such thing as impossible. This is likely the greatest lesson and the greatest inspiration for the rest of the world.” Bruce Aylward, WHO Assistant Director-General and longstanding GPEI helmsman, attributes India's achievement to three factors: “Perseverance, for a start. Perseverance in getting community leaders to engage, in continually adapting strategies to the shifting realities, in going back again and again to be sure every child was getting the vaccine, and, most important, believing, unwaveringly, that the job could be completed.” A second factor was accountability. “The Indian officials put in place mechanisms to hold people accountable for their actions—district magistrates, vaccinator teams, parents, you name it.” Innovation was the third factor. “Huge innovation in every way imaginable. Innovative trials on different polio vaccines, marking children's fingers and their houses after vaccination, training 2·3 million vaccinators, convincing religious leaders to support vaccination.” The demographic implications of India's victory over polio are immense. If southeast Asia is declared free of polio on March 27, the current 52% of the world's population free of polio will increase to 78%. Jumping to 100% means freeing the remaining two regions of polio, Africa and the eastern Mediterranean, which encompass the three countries in the world where polio is still endemic—Nigeria, Afghanistan, and Pakistan. The combined population of these three countries—400 million people—amounts to 6% of the world's population. That doesn't sound a lot but polio eradicators have over the past become inured to living in a frustratingly “so near and yet so far” situation. Today, of the three countries, Nigeria and Afghanistan are on the “near” side and Pakistan, the “far” side. Over the past 12 months, Nigeria has recorded 42 cases versus 104 over the previous 12 months (and only six cases since Sept 5, 2013). “That decline”, Aylward says, “reflects a significant increase in the numbers of people being vaccinated. For the first time, 80% of children received at least three doses of oral polio vaccine in each of the eight high-risk states across northern Nigeria.” Case numbers are going down steadily, despite the murders, attributed to Boko Haram insurgents, of nine female polio vaccinators in northern Nigeria early last year. Case numbers are also declining in Afghanistan, with 16 cases recorded over the past 12 months versus 33 in the previous 12 months. “This drop”, says Aylward, “is linked to successful immunisation efforts in the Helmand and Kandahar provinces, in the southern part of the country, where the Taliban have been traditionally entrenched. Both countries are on track for eradication.” By contrast, polio in Pakistan has become a nightmare for Pakistani health officials and for the global eradication programme. Over the past 12 months, 112 cases were reported there versus 49 in the previous 12 months. The increase is not surprising, given the context: more than 40 vaccination staff have been killed since July, 2012, allegedly by Taliban fighters. In the North Waziristan Agency of the Federally Administered Tribal Areas local leaders have banned immunisation campaigns since June, 2012. “No immunisation means no eradication”, Aylward says. “And already there is evidence of cross-border spread of the virus from Pakistan into Afghanistan. Last year, a Pakistan strain of poliovirus was detected in sewage samples from Egypt, Israel, the West Bank and the Gaza Strip, and exploded into an outbreak in Syria in late 2013.” The Independent Monitoring Board that keeps WHO Director-General Margaret Chan abreast of progress, or lack of it, in eradicating polio, pulled no punches in its Feb 26 report: “The current situation in Pakistan is a powder keg that could ignite widespread polio transmission…The new government has been slow to grasp the fundamental seriousness of the situation. If the current trend continues, Pakistan will be the last place on earth in which polio exists.” How to surmount the Pakistan hurdle? Aylward explains: “First, the murder of health workers has to stop and those responsible must be held accountable. Who pulled the trigger or said that the trigger should be pulled? Then, vaccination has to resume in Waziristan. And that means working out with the Waziri leaders how to get their children vaccinated. Then the full assistance of the Pakistan military is needed to make sure that vaccination can be done safely, especially in the many, large conflict areas.” The programme's worries, however, go beyond the three endemic countries. Last year was marked by a rash of outbreaks in five countries that had been free of polio—Cameroon, Kenya, Ethiopia, Somalia, and Syria. Of the 240 cases in these reinfected countries, 199 occurred in the Horn of Africa (Somalia, Kenya, and Ethiopia) and were caused by a virus imported from Nigeria. As The Lancet went to press, the outbreaks are continuing, but slowing down, thanks to the firewalling of infected areas with massive vaccination campaigns over a period of 18 weeks (seven rounds in Somalia and more than 3 million children vaccinated in Syria, despite the difficulty of reaching children in the conflict-ravaged areas of the country). Not all, though, is gloom-and-doom. Of the three poliovirus strains, the type 2 strain, last seen in 1999, has been eradicated. The third (type 3) strain, last seen in Nigeria in November, 2012, may also have been eradicated. If only type 1 remains, global eradication could be more easily achieved. A further boost to GPEI morale comes from the announcement, on Feb 28, of an agreement by vaccine manufacturers to supply the injectable polio vaccine (IPV) for less than US$1 per dose for the 73 low-income countries eligible for support by the GAVI Alliance, a public-private partnership. The oral polio vaccine (OPV), which has been the vaccine of choice since the start of the programme and has proved highly effective, carries attenuated live poliovirus that occasionally becomes active and spreads the infection. The IPV uses totally inactivated virus that cannot spread and will therefore be a safer tool for the post-eradication strategy. “The race is now on to get all countries using the IPV in order to accelerate the eradication process and—eventually, after eradication—to stop using OPV”, says Aylward. The race is also against time, against donor fatigue, against the fatigue of parents opening their doors to vaccinators time and time again, against the violence perpetrated on vaccinators, and—perhaps most importantly—against a virus that may still be lurking, even in countries freed of polio, in places where children have not been adequately vaccinated. Successes, such as the India triumph, certainly fire hopes of reaching the ultimate goal. But the GPEI certainly won't be resting on the laurels of these successes.