Anti-polio workers shot in Pakistan A Pakistani health worker marks an infant after immunisation with anti-polio drops in Lahore. Photograph: KM Chaudary/AP Gunmen have shot six health workers on an anti-polio drive in a string of attacks in Pakistan this week, officials said, raising fears for the safety of workers immunising children against the crippling disease. It was not clear who was behind the shootings but Taliban insurgents have repeatedly denounced the anti-polio campaign as a western plot. Three women were killed and a man was wounded in two separate attacks on health workers in Karachi on Tuesday, said senior police superintendent Imran Shaukat. An anti-polio worker in the city was also shot dead on Monday, the UN said. The immunisation drive has now been suspended in Karachi, Pakistan's biggest city with 18 million people, health officials said. In the north-western city of Peshawar, a woman supervising an anti-polio campaign was wounded on Tuesday when gunmen on a motorbike shot her in the head, said government official Javed Marwar. All of the victims were Pakistanis working with a UN-backed programme to eradicate polio, which attacks the nervous system and can cause permanent paralysis within hours of infection. It has been eradicated in all but a handful of countries but at least 35 children in Pakistan have been infected this year. In Karachi, health minister Saghir Ahmed said the government had told 24,000 polio workers it was suspending the drive in the province. Officials could not confirm if all of the attacks were linked to the health campaign, said Matthew Coleman, a spokesman for the UN Children's Fund. Many took place in areas notorious for gun violence but the situation was deeply concerning, he said. We're concerned for the safety of frontline workers. They are the true heroes," he said. There have been at least three other shootings involving polio eradication workers this year. Some Islamists and Muslim preachers say the vaccine is a western plot to sterilise Muslims.