Epidemiological Endgame: Is Polio on the Brink of Eradication?

Despite the pointless political assassinations of vaccine workers or the police officers who guard them in a few deeply troubled areas, enough progress has been made against polio in the past year that health experts are now planning for the grand finale—its complete eradication by 2018. The official to-do list of what needs to be done and when to obliterate the crippling childhood disease—which goes by the name Polio Eradication and Endgame Strategic Plan 2013–2018 (pdf)—will be formally presented at an international health meeting in Abu Dhabi on April 25.

"2012 was a very important year for the polio program,” says Hamid Jafari, who directs the World Health Organization’s Global Polio Eradication Initiative. Speaking by telephone in April to group of journalists gathered in New York City to learn about the proposed plan, Jafari said, “We had the fewest number of cases in the fewest countries in the fewest number of districts.”

There is room for cautious optimism. Worldwide, the number of laboratory-confirmed cases of paralytic polio caused by the so-called wild type virus dropped to 223 in 2012—the lowest it has ever been. Just five years ago there were 1,651 cases worldwide, and 20 years before that, in 1988, there were an estimated 350,000 cases. As of April 10 this year there have been 18 naturally occurring cases of polio in the world—eleven in Nigeria, six in Pakistan and one in Afghanistan. (The majority of polio cases in any given year occur in summer and fall.)

The real stunner of 2012, however, was the successful eradiation of polio from India, which accounted for the majority of polio cases worldwide just seven years ago (in 2006).

For years public health experts worried privately whether it was even technically feasible to wipe out polio in such a large, geographically and socioeconomically diverse country. But working with local and international partners, India spent $1.5 billion on the problem and engaged thousands of people from local communities in its anti-polio vaccination and education campaigns. "Polio eradication in India eradicated the excuse of saying it's too hard to reach [hard-to-reach] groups," Apoorva Mallya of the Bill and Melinda Gates Foundation said at the April journalists’ briefing.

At a cost of $5.5 billion beyond what has already been raised, the proposed global eradication plan is by no means inexpensive. One of the great ironies of any disease elimination program (of which polio would be just the third example, after smallpox in humans and rinderpest in cattle) is that the costs to prevent the last several dozen cases are quite high compared with the previous hundreds of thousands. The extra complexity of including the hardest-to-reach people and places adds significantly to the price. But most health experts and certainly billions of parents around the world see polio eradication as a good investment that yields priceless benefits in terms of lives saved and the prevention of lifetime paralysis.

Successfully wiping out polio is by not, however, a foregone conclusion. All the world’s governments—working through the World Health Assembly—had previously set 2000 as the target year for polio eradication. But five years later it was clear the effort had fallen short: annual polio numbers were stuck between about 1,000 and 2,000 cases globally. Financial shortfalls and social upheaval played significant roles in missing that earlier deadline.

A closer look at the current plan shows, once again, that the remaining bottlenecks tend to be financial, political and sociological as opposed to technological. The few scattered areas where naturally occurring poliovirus still cripples young people tend to be, practically by definition, some of the poorest, most chaotic environments imaginable.

“What’s new [in the 2013-2018 plan] is that this is a coordinated action to interrupt virus transmission,” Stephen Cochi of the U.S. Centers for Disease Control and Prevention said at the journalists’ briefing. Focusing sustained effort on the three remaining endemic countries all at once offers the best chance of ensuring that none of them can rekindle polio’s spread to nearby areas and the rest of the world.

Polio still occurs naturally in tribal regions of northern Pakistan, the northern part of Nigeria and sections of eastern and southwestern Afghanistan. Progress in these areas has been maddeningly uneven at times. The number of polio cases in Nigeria, for example, fell from 798 in 2008 to 62 in 2011 before climbing to 122 last year.

In addition to regular polio campaigns in the more stable areas of Pakistan, for example, health workers focus a lot of attention on travelers and border towns adjacent to insecure areas. And many people living in North Waziristan in Pakistan (where militants have banned polio campaigns and an estimated 240,000 children have not been vaccinated since mid-2012) have traveled 160 kilometers or so outside the tribal area to have their children vaccinated.

Islamic religious leaders are also playing an increasingly prominent role in promoting both vaccination and, ultimately, eradication of polio. A meeting of Muslim scholars from several countries in Cairo earlier this year reaffirmed the importance of polio vaccination for children of the Muslim community, or Ummah. “Crippled children lead to a crippled Muslim Ummah,” Ahmad al-Tayyeb, the Grand Imam of Al-Azhar and one of the most highly respected authorities in Sunni Islamic thought, warned.

Just as important, various polio campaigns in different countries have stepped up their outreach to local communities to find ways that the vaccination program can dovetail with other public health needs. In many areas, for example, polio workers are now also teaching young mothers about the benefits of breast-feeding and spreading the word about good nutrition, hand washing and effective treatments for diarrhea.

Given the nature of infectious diseases and their ability to pop up unexpectedly, the world may never have a better shot at eradicating polio than it has this year. One last coordinated and well-financed effort might just do the trick. And then, perhaps, we can start talking about eliminating measles, which kills about 150,000 children around the world each year.

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