On the third day of a massive anti-polio drive in southern Pakistan, one of only two countries where the disease has not been eradicated, a suicide bomber blew himself up outside a vaccination center Wednesday, killing at least 14 members of Pakistani security forces.
Officials said 20 others were wounded, some critically, in the explosion in Quetta, the capital of Baluchistan province.
It was the latest deadly attack aimed at the anti-polio campaign in Pakistan, where Islamist extremist groups believe the vaccine is a front for Western espionage. The Pakistani Taliban militant organization claimed responsibility for the bombing in a Facebook post.
Officials said the bomber approached a vehicle near the polio center in Quetta's Satellite Town district and detonated nearly 20 pounds of explosives. Neighbors said the explosion caused cracks in nearby houses.
At least 13 police officers and one member of the paramilitary Frontier Corps were killed. Officials said the death toll could rise further.
The United Nations and international relief groups have long backed Pakistan's campaign against polio, a crippling childhood disease that still circulates only here and in neighboring Afghanistan.
The three-day vaccination drive in Baluchistan and Pakistan's tribal belt, near the Afghan border, began Monday and was due to reach 2.4 million children younger than 5, including more than 55,000 children of Afghan refugees, officials said.
Tight security arrangements had been taken for the protection of volunteers and health workers, dozens of whom have been killed in previous attacks.
Pakistan saw a steep drop in new polio cases in 2015 as the army targeted militant strongholds in the tribal belt, improving access for health workers. Health officials said 52 new polio cases were reported in 2015, compared to 306 cases a year earlier.
Yet Pakistan's struggles with the disease mark a sharp contrast with its neighbor, India, which Wednesday marked five years without a new polio case. Nigeria, too, has made great strides against the disease, and last year was removed from the list of countries where polio is endemic, having not recorded a new case since July 2014.
Ali is a special correspondent. Times staff writer Bengali reported from Mumbai, India.
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