Posted on behalf of Katherine Rowland.

When Afghanistan instituted a door-to-door polio vaccination policy in 2000, the complete eradication of the disease seemed within reach. Between 1999 and 2004, the number of new cases fell from 63 to 4.

However, with the escalation of violence in the country in 2005, hopes for complete elimination diminished as vaccinating became more difficult. Figures just released by the Afghanistan Ministry of Health indicate that between 2010 and 2011 the number of new infections tripled, from 25 to 76 cases (see the New York Times story).

Although 76 may seem like a small number in a country of more than 34 million people, the figure is still a cause for concern. Polio is a crippling and potentially fatal infectious disease with no known cure. Although it can occur at any age, it typically affects children under five years of age.

Over the past quarter-century, vigilant vaccination campaigns have achieved near-universal elimination of the disease. The Global Polio Eradication Initiative, launched in 1988, has reduced incidence by more than 99%. Last week, India, once burdened with high rates of polio, celebrated one year of being completely free of new cases (see ‘India on track to be declared polio-free next month’) .

The disease remains endemic in only three countries — Nigeria, Pakistan and Afghanistan — and has recently re-emerged in Chad, Angola, and the Democratic Republic of Congo. It’s no coincidence that each of these countries is also a region of ongoing conflict. Political insecurity, violence and poor infrastructure each have a major role in the persistence of the last 1% of the disease.

Sona Bari, spokeswoman for the World Health Organization’s Global Polio Eradication Initiative (GPEI), describes the cases in Afghanistan as the “hardest of the hard cases”. Political upheaval, high levels of transmission and poor services all make it difficult to administer vaccines. Afghanistan’s proximity to Pakistan, where infections are also on the rise, contributes to the problem (see ‘Polio clings on in Pakistan’).

Although Afghanistan’s ongoing conflict has contributed to the increase in new polio infections, the situation has also given rise to unlikely alliances to bring the disease under control. Heidi Larson of the London School of Hygiene and Tropical Medicine, UK, says that collaboration to combat polio can serve as a form of “soft diplomacy”. International aid organizations have forged agreements with not only the Ministry of Health, but also with anti-government groups to ensure safe access to hard-to-reach communities.

“We have only one focus,” says Bari. “And that’s to vaccinate our children. No matter who supports that, we’re with them.”

The drive to rid the country of polio has also fueled innovations in vaccination delivery. In 2010, President Hamid Karzai introduced National Polio Immunization Days. Held four times a year, the initiative sends tens of thousands of medical staff and volunteers to immunize millions of children around the country. New teams of volunteer vaccinators have been set up within communities to better serve regions that are otherwise inaccessible.

The development of monovalent oral polio vaccine (OPV) in 2005 has helped rapid immunization. Historically, standard OPV was administered in two doses over a period of four to six weeks. The short-interval, additional-dose approach reduces that time to just one to two weeks, making it more probable that people will get the doses they need to be fully protected.

Despite the rise in new cases and ongoing political problems, the Ministry of Health continues to uphold the goal of polio eradication by 2013. “Everyone needs to strive for that goal,” says Larson. “This is a fantastic opportunity for the world, and it’s so close, and yet so precarious.”