Islamabad - Pakistan's volatile northwestern city of Peshawar is the largest reservoir of endemic polio viruses in the world, the World Health Organization said on Friday, amid concerns over continuing violence against polio vaccination teams.
Pakistan is also the only polio-endemic country in the world where polio cases rose from 2012 to 2013, the statement said. There were 91 cases last year but only 58 the year before.
Polio can permanently paralyze or kill victims within hours of infection. Intensive vaccination campaigns have almost eradicated the disease worldwide, but it remains endemic in Pakistan, Afghanistan and Nigeria.
In Pakistan, Taliban commanders have forbidden vaccination teams access in some areas. A handful of religious leaders have also denounced the campaign as a plot to sterilize Muslim children.
The rhetoric has fueled violence against the vaccination teams. Many teams travel only with police protection. Last year there were more than 30 attacks on polio teams.
But Dr. Elias Durry, the head of the WHO's polio eradication program in Pakistan, emphasized that campaigns in most parts of the country had been successful.
"The virus has not been seen in all parts of Pakistan," he said. "It's in very limited areas that we have problems in accessing."
Some of the attacks took place in Peshawar, the capital of northern Khyber Paktunkhwa province. The old city is a maze of shops and homes where open sewers run through the streets.
The city is plagued by Taliban and sectarian violence. Many families fleeing the Taliban insurgency in the north seek refuge there.
Peshawar's huge, mobile population and poor sanitation make it an ideal incubating ground for the disease. More than 90 percent of Pakistani polio cases last year were linked to a strain of disease found in the Peshawar sewers.
All but one of the 13 cases in Afghanistan were also linked to Peshawar, WHO said.