Polio expert Bruce Aylward on eradicating the disease worldwide - Macleans.ca

Polio expert Bruce Aylward on eradicating the disease worldwide

And why a failure to immunize every child could lead to an outbreak here


Darrin Vanselow

A Canadian physician and epidemiologist, Dr. Bruce Aylward, assistant director-general at the World Health Organization (WHO), oversees its polio eradication initiative—a massive global effort that aims to have the world declared polio-free in 2018. The polio virus, which affects mainly children, can cause paralysis, sometimes within a matter of hours, and death; the fight to stop polio is the largest public health project in history. Aylward is based in Geneva.

Q: How did you come to head the WHO’s polio eradication program?

A: I grew up in Newfoundland and did my medical training at Memorial University. While I was there, back in 1984, I went to Uganda, where I first started my work in vaccination. That whetted my appetite to move from what I thought was going to be a career in surgery to public health and vaccines. I’ve been with the WHO since about 1992. I was in the field in Egypt and the Middle East, then Cambodia, India, Burma, the ’Stans and everywhere in between. The whole time, I was working on starting up the polio eradication program. When I came back to Geneva in the late ’90s, I was asked to head up the global program. I took over what was a relatively small program. Now it’s the biggest internationally coordinated health initiative in history, in terms of the numbers of countries and people involved in trying to get kids vaccinated to eradicate a disease.

Q: Why target polio for eradication?

A: There are very few diseases that can be eradicated. Polio met the basic criteria: It only survives in humans; there was a vaccine that could interrupt person-to-person transmission; there wasn’t a chronic carrier. Any eradication program is a huge financial cost [the overall cost of this program is US$9 billion], and that has got to pay off. There’s got to be the societal and political will. At the peak of our program, there were between 10 and 20 million people a year involved in the vaccination of over half a billion children. This was a huge effort. The thing about polio—this was a disease for which there was no vaccine 50 years ago. So, some of the people who were in important decision-making positions, whether politicians or donors, grew up in a world where they saw polio, and they knew the terror of this disease. They knew about schools being closed. They knew the terror of one of their friends disappearing. They knew of the iron lungs. And they knew that there was an oral vaccine—not just an injectable vaccine—that two drops can give.

Q: How do we eradicate a disease?

A: A number of key criteria have to be in place. One is proof of principle: that you’ve done it in one area of the world, so it can be done globally. But [in different countries], the outcome is never quite the same. Our proof of principle was in the Americas, where the big work on eradicating polio was done in the mid-1980s. [The last reported case there was in 1991.] The Americas have pretty high routine immunization coverage; a homogeneous language, more or less; and a sense of common purpose, certainly in public health. There’s a sense that the polio program is all about taking what we learned in the Americas and just doing that everywhere else, but that doesn’t necessarily translate to a setting like northern India, or Somalia.

From 1988, when the eradication initiative was launched, through to 2000, there was a steep decline in cases. It went from an estimated 350,000 a year right down to the low thousands, very quickly. But then it flattened out, with cases hovering around the low thousands for nearly 10 years. [Polio transmission was stopped] in almost every country except for Nigeria, Pakistan, Afghanistan and India. And although only four countries had never stopped polio, probably at any one time, 10 or 15 were getting reinfected. It was a challenging 10 years. During that period, there was a huge amount of innovation in the program: everything from reinventing the vaccines, to changing the way we hold staff accountable, to genetic sequencing we use to track the virus—everything. At the end of the day, it’s still the same challenge of getting every kid vaccinated. How do you get to those kids? How do you prove you got there? What do you vaccinate them with? All those things have been refined to try to knock out an incredibly tenacious virus.

Q: India, which just marked three years since its last reported case of polio, is set to be declared polio-free. How big of an achievement was that?

A: We crossed the Rubicon. To put it in perspective, there have been six eradication initiatives in history. Three have failed: against malaria, yellow fever and a disease called yaws. There’s been one success, and that’s smallpox. Polio is ongoing, as is guinea worm. When you look at the three initiatives that failed, it was because of technical flaws. Malaria, we couldn’t interrupt transmission. Yaws, it turned out there’s a subclinical condition of the disease we couldn’t see. Yellow fever survived in monkeys.

With polio, around the mid-2000s, we ran into huge problems. Egypt was proving impossible. We had very high coverage, but we couldn’t stop the disease. People began to say there’s a technical flaw; it works in places like the Americas, but not when you get into the population size, density and sanitation problems of greater Cairo. There are 18 million people crammed into that area. In northern India, there are hundreds of millions of people crammed into a small area. Basically, [the concern was that] sanitation was so bad, you may not be able to stop the kids from getting infected. That’s what people thought in the mid-2000s. And then, for Egypt, we developed a new formulation of the vaccine. We tinkered further with the vaccines, and that helped us get over the hump in India. With India now polio-free, that means the technical issues have been resolved. Now it’s about the political and societal will to vaccinate your kids and protect them from a devastating disease. That’s it.

Q: Could we see polio again in the Americas?

A: Absolutely. Immunization rates in the West aren’t perfect. If the virus got into, say, an inner city where there are lots of unvaccinated kids all clustered together, there would be a risk of an outbreak. But in Canada, you have high levels of sanitation. The probability of a substantive outbreak is unlikely, but the possibility is very real. That’s why Canada has got a vested interest in getting rid of this. Every kid, everywhere, is going to benefit in perpetuity from [getting rid of polio].

Q: How close are we today?

A: We’re closer than we’ve ever been. When we started, 1,000 [kids were paralyzed] every day. Now it’s around 327 cases for last year. We don’t know how many countries had what we call indigenous polio [when the program started], meaning they’d never stopped it, but it was probably over 125. As of today, there are only three countries that never stopped the virus. And, in those countries, it’s only part of the country that never stopped it. Basically, there are maybe 30 districts in the world that have not stopped polio. It’s a very small area, but these are very tough places.

Q: So where are they?

A: The southern part of Afghanistan is one—Helmand and Kandahar [provinces]. In Pakistan, it’s primarily along the border with Afghanistan, in the Federally Administered Tribal Areas. In Nigeria, it’s mostly in Kano [State], which is big, population-wise, and Borno [State] in the northeast, where Boko Haram [an Islamist terrorist group] has been active. Those are the last reservoirs of indigenous virus.

From there, the virus spreads. We had 180 cases in Somalia last year, from a virus imported from Nigeria. Similarly, the virus spread from Pakistan to Egypt in late 2012, and then has been found in Israel and Palestine, and caused the 17 cases we’ve seen so far in Syria. There are about 13 cases in Afghanistan this year, but all of those are coming across the border from Pakistan, with the exception of one case in the southern region. Cases are up globally this year, but if you look at Nigeria, we’re down 60 per cent from last year. In Afghanistan, there’s been a 70 per cent decline since last year. Pakistan’s a different issue.

Q: Will the world be polio-free by 2018?

A: The first milestone is to stop transmission globally by the end of 2014. Now, who’s on track? Nigeria, if they can sustain this, and let’s hope they do, because they go into federal elections in 2015, so the window to get it done is now, while politicians can still give attention to this. In Afghanistan, there’s been huge progress. They could knock this out. But they will always be restricted by what’s happening next door in Pakistan, because they keep getting reinfected.

The big concern is Pakistan. In the north, in Waziristan, there was a ban on vaccination [introduced] about a year and a half ago. The government of Pakistan has got to get negotiating, and get to an agreement with that leadership. The next challenge is in the Khyber area, where military operations prevent vaccination. Most importantly, you’ve got to stop shooting your vaccinators. We’ve had over 25 vaccinators or police escorts shot and murdered. Not a single one of these people has been brought to account. This is not about polio. That’s just basic rights to health.