The rugged Pakistani region of North Waziristan emerged as a hotbed of polio infections after Taliban militants in the isolated area banned immunizations. Now the Pakistani government's offensive against the militants has sent a half-million refugees fleeing the territory, creating both perfect conditions for the disease to spread and a golden opportunity to immunize many thousands of people.
"We know polio is a disease, but we also know the Taliban can kill if you violate their instructions," said Mohammed Gul, who fled North Waziristan this week and is living in an empty government school with his nine children.
Taliban militants banned vaccinations in the summer of 2012, saying they would allow them only if the U.S. stopped drone strikes. The result has been a spike in polio infections in Pakistan, which is one of only three countries where the disease has never been eradicated.
The number of cases in Pakistan dropped from 198 in 2011 to 58 in 2012. Infections then rose to 93 in 2013. So far this year, 54 of Pakistan's 83 confirmed polio cases have been in North Waziristan. In fact, North Waziristan accounts for roughly half of the total polio cases confirmed worldwide so far in 2014, according to the World Health Organization.
The massive Pakistani military operation started June 15. Health officials did not have any advance notice of the offensive, but the WHO made plans as early as February to be prepared if anything happened.
Polio, a highly contagious virus transmitted in unsanitary conditions, is easily fended off with a vaccine. But once a person's nervous system is infected, paralysis can happen within hours, and there is no cure. The virus affects mostly children under 5.
"In a nutshell, this is an opportunity, but the risk is also there," said Dr. Nima Saeed Abid of WHO's Pakistan office, which helps the government with its polio-eradication program. "If we reach the children with this opportunity, there is great hope."
The government has been trying to vaccinate refugees as they cross into the neighboring regions. Dozens of checkpoints are set up along the roads where refugees are offered drops of the oral polio vaccine. About 265,000 people have been vaccinated that way in June, said WHO officials.
But polio-eradication efforts usually rely on multiple rounds of vaccination. The goal is to have enough people immunized so the disease can't find a suitable host and eventually dies out. But there is no central place in which to give vaccinations because almost all the refugees from North Waziristan have chosen to stay with family members or to rent homes instead of living in the government-run camp.
Instead, officials will go door-to-door in blanket vaccination campaigns that target all residents, including refugees. One such campaign just finished, and Dr. Raheem Khattak, who's in charge of the provincial immunization program, says four more are being planned.
But the massive influx of refugees taxes the region's health services and basic water and sanitation. Huge numbers of people living in close, dirty conditions create perfect conditions for the virus. The refugee crisis also comes in the hot summer months, when the virus is most likely to spread.
There's also no guarantee that the refugees will stay in one place, meaning they could take the disease with them wherever they go. After previous military operations in the northwest, tens of thousands of refugees have gone to places such as Karachi along the southern coast.
So far, health officials say, few people are rejecting the vaccination. Many Pakistanis have been distrustful of anti-polio drives, fearing they were a plot to sterilize Muslims.
At the main hospital in Bannu, polio worker Mohammad Saqib said he vaccinated hundreds of children in the past two weeks, and the families happily agreed. But in an indication of how much fear the militants still command, parents did not want the vaccinations to leave any evidence.
"They say, 'Just give polio drops to our children, and don't put any mark on their fingers with ink, so that when they go back, Taliban don't harm them,'" he said.