Afghanistan, Nigeria and Pakistan are the only three countries to have never interrupted spread of polio virus and, therefore, stand in the way of the two decades-long effort to make polio the second human disease to be eradicated, after smallpox. In 1988, there were an estimated 350,000 cases of polio, while last year the WHO recorded just 650. However, since 2001 the number of cases worldwide has hovered around 1,000.
“It’s now shifted to the relentless pursuit of the unvaccinated child, this is what the programme is all about,” said Bruce Aylward, an assistant director general at WHO who heads the Global Polio Eradication Initiative, at a press conference at the 65th World Health Assembly in Geneva today.
The plan calls for increased focus on regions and populations in Nigeria, Pakistan and Afghanistan where vaccination rates are the lowest and polio cases still occur, emphasizing measures tailored to them: In northern Nigeria that means focusing on tracking migrant population likely to be missed in vaccination campaigns and working with religious leaders to dispel rumours that the vaccine causes infertility and other health problems, to give two examples. In Pakistan’s Federally Administered Tribal Areas, one effort outlined in the plan calls on vaccine workers to focus on transit corridors to reach migrant populations there.
“It’s a very ambitious program,” says Zulfiqar Bhutta, chair of the Department of Paediatrics and Child Health at Aga Khan University in Karachi, Pakistan. “The devil is in the detail of implementation.”
There are early signs that such measures, many of which are already in place, are working. In 2011, polio cases were up 220% in Afghanistan, 185% in Nigeria and 37% in Pakistan, compared with 2010. Compared to this time last year, Afghanistan and Pakistan have reported far fewer cases of polio. The 64 cases worldwide reported so far this year are the lowest ever, Aylward noted at the press conference.
In February, meanwhile, India celebrated a full year without a case of polio (see India on track to be declared polio-free next month). Many people assumed that India would be one of the toughest countries to eradicate polio because of high population density and poor hygiene.
“The success in India was remarkable,” says Nick Grassly, an epidemiologist at Imperial College in London. “The eradication in India indicates that the barriers are not technical, they are about management, implementation, oversight, and commitment to eradicating polio when it’s not at the top of the list of the things that [countries] are keen to do.”
The eradication initiative is $945 million short of reaching its more than $2 billion budget for 2012-2013. The shortfall has already forced the initiative to cut vaccination campaigns in countries where the virus is not endemic but remain vulnerable because they border endemic countries.
“If the money doesn’t come and they can’t build these walls of immunity, there is risk polio will implant itself and start circulating,” says David Heymann, head of the Centre on Global Health Security at the Chatham House in London. Last year, China’s western Xinjiang province experienced a polio outbreak traced to viruses similar to those circulating in Pakistan.
Heymann, a former representative of the Director-General for Polio eradication at WHO, says the polio campaign, which has already cost $9 billion, has come too far to fail. “It must succeed and we must continue until it has succeeded.”
Image of polio vaccination in Nigeria courtesy GPEI