ISLAMABAD: Pakistan is moving closer to eradicating polio, officials said Tuesday, with no fresh traces of the crippling childhood disease found in sewage samples taken from 40 high-risk sites across the country over April.

“This is in line with our objective of eliminating polio by the end of the year,” said Rana Safdar, national coordinator of the Emergency Operation Centre tasked with eliminating the disease which is endemic to Pakistan and neighbouring Afghanistan.

He said 11 new polio cases have been recorded in humans since the start of the year compared to 25 in the same period in 2015, a year which itself saw an overall decline in incidents of the disease.

April was the first month since testing of sewage began that zero samples taken from 40 high-risk urban sites tested positive.

“It does not mean that we have cleaned the country of polio, but we have a lot of confidence that the intensity of the virus transmission has decreased to an all-time low,” said Safdar, adding the result was particularly important because it comes at the onset of summer when the virus is most contagious.

Attempts to eradicate polio in Pakistan have been hit by militant attacks on immunisation teams that have claimed more than 100 lives since December 2012.

But Safdar said an improving security situation and efforts to educate communities who have traditionally been suspicious of vaccines has reduced the percentage of unvaccinated infants to “negligible”, against 5 per cent in 2015 and 20pc in 2014.

In addition to their normal campaigns, polio vaccination teams are concentrating their efforts in higher-risk zones, for example the militancy-wracked Pakistan-Afghanistan border region and Afghan refugee camps.

Pakistan hopes to be removed from the list of polio-endemic countries by 2018 by achieving its goal of no fresh cases for a year.

Polio is a highly contagious disease caused by a virus that invades the nervous system and can cause total paralysis within hours. It mainly affects children under the age of five.

There have been no fresh cases of wild polio viruses in Africa since August 2014, though the disease was endemic in 125 countries in 1988.

Religious opposition to all forms of inoculation grew after the CIA organised a fake vaccination drive to help track down Al Qaeda's former leader Osama Bin Laden in the town of Abbottabad. He was killed there by US forces in 2011.