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CSU 65/2010: POLIO – A PATHOGEN ON A PRECIPICE

Tuesday, 1st of June 2010

CSU 65/2010:  POLIO – A PATHOGEN ON A PRECIPICE

 There is a temptation in running, as in eradication, to slow down as one approaches the finish line. ‘There are so many claims on our resources. Why should we spend billions on a disease which claims so few victims?’ this specious line of reasoning needs careful, data based analysis and refutation. If we stop short of victory, then the 22 years we have spent on eradicating polio will have counted for naught.

 

Good reading, BD

 

outline goes here

The Lancet Infectious Diseases, Volume 10, Issue 6, Page 367, June 2010

 

 

Polio—a pathogen on a precipice

Original Text

30 years ago, on May 8, 1980, the World Health Assembly formally recognised the global eradication of smallpox. For thousands of years the disease had claimed many millions of lives (an estimated 300 million to 500 million in the 20th century alone). The culmination of 200 years of public health efforts from Edward Jenner's discovery of the cowpox vaccine, the achievement was a milestone in global health and gave hope that other diseases might too be consigned to the history books. But despite efforts before and since the eradication of smallpox, no other infectious disease has been successfully eradicated, and to some people the demise of smallpox seems like a fluke.

Efforts to eradicate yellow fever, yaws, and malaria have all fallen by the wayside; or, if not completely forgotten, their realisation seems a long way off—in the 1950s and 1960s people talked of malaria eradication in decades, now we talk of it optimistically in terms of the next century. Programmes for perhaps the two most promising candidates, polio and dracunculiasis, have seen eradication come tantalisingly within reach, but both diseases cling on in a few endemic countries from which outbreaks in non-endemic countries emanate—such as the polio outbreak in Tajikistan this year.

Polio, like dracunculiasis and smallpox, has no non-human reservoir and has known preventive interventions, in this case highly effective vaccines, and therefore is an attractive target. And the prominence of the disease in high-income countries charged early control efforts. In the USA, for example, President Franklin D Roosevelt, who was paralysed by the disease, initiated the huge charitable fundraising efforts known as The March of Dimes, which was instrumental in funding the development of both Salk and Sabin polio vaccines. Resulting immunisation programmes in the USA and Europe staring in the 1950s saw rapid and early success. The incidence of polio in the USA and Europe declined rapidly, and in 1960 Czechoslovakia became the first country to declare polio eradicated. In 1985 the Pan American Health Organization launched an initiative to eradicate polio from the Americas, and in the same year, the Rotary Organisation pledged to raise US$120 million to immunise all children worldwide. With such positive initial gains WHO, UNICEF, the Rotary Organisation, and the US Centres for Disease Control and Prevention launched the Global Polio Eradication Initiative in 1988.

Within the first 5 years of the initiative, global incidence of the disease declined from an estimated 350 000 to 100 000. Since then, enormous gains have been made freeing much of the world from the crippling viral disease, which is now endemic in just a handful of regions in four countries: Afghanistan, India, Nigeria, and Pakistan. Nonetheless, despite 22 years of gains, in the past 5 years the disease and its would-be eradicators have reached something of a stalemate. Each year 1000—2000 people have been affected by the disease, with outbreaks in both endemic and non-endemic countries. The impasse has led some to question the goal of eradication. Given the low incidence of the disease, are the benefits of achieving eradication worth the ongoing expense? But this question misses the point—the incidence is so low only because of eradication efforts; were surveillance to be relaxed and were mass immunisation campaigns to give way to routine vaccination alone, numbers of cases would surely rise again, and the disease spread to regions from which it has been eliminated.

Clearly, new approaches are needed to achieve eradication in the last strongholds. In a new strategic plan launched in April, the Global Polio Eradication Initiative highlights that, in addition to the old tools of government accountability, mass immunisation, and public engagement, new diplomacy, education, and accountability on ever more local levels are needed to reach the specific populations affected. In India, for example, the disease is not a national problem, but associated with populations in Uttar Pradesh and Bihar in the northwest, so targeting these regions and migrants from them will be essential in preventing the spread of disease.

The eradication of polio seems imminent, but with so few cases, there is a temptation to think an acceptable level of infection has been achieved. Not so. To stop short of eradication would not only be a snub to the hundreds of thousands of health workers and community members involved in the effort so far, but also would risk resurgence of a disease that for many is now a distant memory. The new levels of engagement in the last strongholds of polio will sever its grip from the precipice to which it clings. We look forward to 30 years or so from now, when we can reflect on the polio eradication programme and its legacy in global health.