An Afghan girl has been diagnosed with polio in Kabul - the capital's first case since the Taliban's fall in 2001.
The health ministry ordered a vaccination campaign across the capital after the three-year-old was diagnosed.
Polio remains endemic in Afghanistan, Pakistan and northern Nigeria, but has been almost wiped out around the world.
In all three countries Islamic extremists have obstructed health workers, preventing polio eradication campaigns from taking place.
Since the Afghan Taliban changed their policy, allowing vaccination in recent years, there has been a decline in cases in Afghanistan.
There were 80 cases in 2011, 37 in 2012, and 14 in 2013.
The emergence of a new case in Kabul is worrying health officials.
It was discovered in a very poor community of Kuchis, formerly nomadic herdsmen, now settled on a hillside in the east of the capital.
In response, health workers have tried to visit every home in the community.
There is no running water or electricity, and some of the ex-nomads still live in tents, despite the cold of winter in Kabul.
Once the workers have put drops into the mouths of infants they find, they mark their hands with a blue line, and write the date on the wall.
It seems rudimentary, but tens of thousands of volunteers in campaigns like this across the country have succeeded in almost beating the disease.
The girl who contracted the disease, Sakina, was diagnosed after she became paralysed.
Her father is a taxi driver who often goes to the frontier region with Pakistan, and has now taken her there for treatment.
Her uncle, Mohammed Azim, said that she complains: "I can't stand up. The other children are playing and I cannot."
The polio strain in the two countries is identical, and with 1.5 million children crossing the frontier every year, cross-border transmission is inevitable.
Nearly all of the cases in Afghanistan last year were in regions close to the Pakistan border.
Afghanistan has health workers at the border crossings, attempting to monitor all children who cross, and vaccinating those at risk.
But many people do not cross at formal customs posts, instead using tracks across the mountains and deserts that line the porous frontier.
The Taliban in Afghanistan remain a nationalist movement, who have been persuaded of the values of modern medicine.
But the Pakistani Taliban are a far more ideological group, similar to Boko Haram in northern Nigeria, who are focused on global jihad, and unwilling to believe anything the west tells them.
As well as killing health workers, the Pakistani Taliban have campaigned against vaccination, spreading the malicious rumour that it is a covert policy of sterilisation.
Their opposition, along with continuing insecurity in some parts of Afghanistan, could prevent continuing progress towards global eradication of the disease.
Afghan Health Minister Soraya Dalil said the continuing opposition of the Pakistani Taliban was a threat, "undermining efforts" to eradicate polio in Afghanistan.
After the initial local vaccination campaign, routine campaigns would continue, she said, to keep up the pressure, and ensure that this is an isolated case and not a new outbreak.
"This new case in Kabul tells us that the effort on polio eradication is not over yet, and we have to accelerate the effort to make sure that every child, no matter where they are, receive polio drops."