ISLAMABAD, Pakistan -- A land mine blast killed two polio vaccination workers in northwest Pakistan on Thursday, the latest in a recent wave of violence involving healthcare teams trying to eradicate the disease in the South Asian nation.
The blast occurred in Pakistan's Kurram region, one of several remote tribal districts along the border with Afghanistan that have long harbored Islamic militants. Healthcare workers Muzamel Hussain and Akbar Badshah had been administering polio vaccination drops to children in the village of Malikhel and were on their motorcycle when a mine in the road exploded, Kurram officials said.
In recent months, Pakistani Taliban leaders have denounced vaccination drives by United Nations-backed Pakistani healthcare workers as a guise for American spying activity, and have unleashed a campaign of targeted attacks against polio vaccination workers across the country.
At least 11 vaccination workers have been murdered in Pakistan in the last two months. The explosion in Kurram marked the third attack involving polio vaccination teams this week.
On Tuesday, gunmen on a motorcycle opened fire on a police officer guarding two female vaccination workers in the northwest city of Swabi, killing the officer. The vaccination workers escaped unhurt.
Also on Tuesday near the northwest city of Mardan, a man attacked a polio vaccination volunteer with an ax, injuring the volunteer's hand.
Officials said they were still trying to determine the motive behind the attack in Kurram, adding that polio vaccination teams working there in the past had never been threatened. Officials said the blast was caused by a land mine, and that it was unclear whether the men were targeted because of their vaccination work.
Kurram has a large Shia Muslim population, and land mines are often used in sectarian violence between Sunni and Shiite Muslims in the area.
Pakistan is one of three countries where polio remains endemic -- the other two are Afghanistan and Nigeria. Last year, the number of polio cases in Pakistan dropped to 56, from 173 in 2011.
Caused by a virus that attacks the nervous system, polio is highly communicable and can result in irreversible paralysis within hours of infection. Found more often in countries that lack proper sanitation and hygiene, it mostly affects children under the age of 5. The virus typically enters the body through the mouth and is spread through fecal contamination of food or beverages.
Pakistani officials have struggled to safeguard polio vaccination teams in the face of persistent attacks from militants. After assailants killed nine vaccination workers in Karachi and northwest Pakistan's Khyber-Pakhtunkhwa province in December, authorities began deploying police to accompany anti-polio workers as they moved through neighborhoods and villages.
Earlier this week, officials in the central city of Gujranwala said they would assign 800 police officers to guard 800 two-member polio vaccination teams working in the city and surrounding villages, Pakistani media reported.
Many parents, particularly in northwest Pakistan, harbor intense mistrust for polio vaccination efforts. A CIA-orchestrated phony vaccination scheme aimed at finding Osama bin Laden in the military city of Abbottabad in 2011 helped fuel that mistrust, health officials say. But skepticism about polio vaccination drives has also been stoked by radical Islamic clerics who spread rumors that vaccines cause infertility.
Staff writer Alex Rodriguez reported from Islamabad, and special correspondent Zulfiqar Ali reported from Peshawar, Pakistan.