JUDY WOODRUFF: Next:Despite huge strides to wipe out polio around the world, the crippling virus still haunts a few places.One of them is Pakistan, where there have recently been a series of attacks on those trying to administer vaccines.

Today, two people were killed and at least 12 injured after a bomb attack outside a government health center in the Northwest Province.

Special correspondent Fred de Sam Lazaro has our report on the setbacks to eradicating the disease.

FRED DE SAM LAZARO: This slum in Karachi is one of the last places in the world where polio is still a threat.Pakistan had tens of thousands of cases just a decade ago, and came close to wiping it out.Neighboring India, with similar or worse conditions, like urban crowding and poor hygiene, was certified polio-free in 2012.

DR. ANITA ZAIDI, Pakistan:The fact that they have done it is what makes me think that we can do it, if you can put enough boots on the ground and do high-quality campaigns, because, if India can do it, Pakistan can do it.

FRED DE SAM LAZARO: But, in Pakistan, Dr. Anita Zaidi says, the polio campaign began to stall, thanks to epic floods, political turmoil, and religious extremists who have fought the polio campaign with guns and rumors.

And there was one more unexpected setback.

PRESIDENT BARACK OBAMA: We developed more information about the possibility that we had located bin Laden hiding within a compound deep inside Pakistan.

FRED DE SAM LAZARO: One part of that intelligence-gathering was a fake vaccine campaign in the neighborhood around the al Qaeda’s compound used to gather DNA samples.

ANITA ZAIDI: Which has hugely damaged public health programs, not only in Pakistan, but in many, many countries, because people ask all kinds of questions.They now think that the vaccine programs might actually be spy operations.

FRED DE SAM LAZARO: It’s also helped revive a rumor long fueled by extremists that the polio campaign is a plot against Muslims.That lie frustrates businessman Aziz Memon.He’s with Rotary International, which has spent $1.2 billion and led the global polio effort.

AZIZ MEMON, Rotary International:They issued a ban on polio immunization, which is today also existing.These are the same people who at one time were rejecting it on the basis that it is going to make the child infertile.

FRED DE SAM LAZARO: So the vaccination campaign recently enlisted prominent mainline religious leaders.

ANITA ZAIDI: The Council of Islamic Ideology now has a very active program, and there is a declaration that the Council of Ulemas has made that says that the polio vaccine is effective, that it’s not harmful, and it is allowed by Islam and that Muslim children can have it.

FRED DE SAM LAZARO: Muhammad Hanif Tayyab helped author the document, which is being distributed to mosques across Pakistan.

MUHAMMAD HANIF TAYYAB, Pakistan (through interpreter): They will go and explain to the people, look, in the rest of the Muslim world, in Iran, in Saudi Arabia, this crippling curse has been eradicated.Why is it that we cannot eradicate it from our country?

FRED DE SAM LAZARO: The declaration or fatwa by top leaders has enabled local imams like Bilal Ahmed to tell his congregants, most of them not literate, that the vaccine is not haram, or anti-Islamic.

IMAM BILAL AHMED, Pakistan (through interpreter): People come to me and ask if it is haram, and I say you’ve been taking English medicines all your life, and none of them are haram.So why would this one be?

FRED DE SAM LAZARO: Such reassurances haven’t made life any safer for vaccinators.At least 22 have been gunned down in the past year or so.

AZIZ MEMON: They love to target them, not just because of polio, but because touching a polio worker makes news.They know that.I will give you one example…

Polio workers, they love to target them, not just because of polio, but because touching a polio worker makes news.They know that.

FRED DE SAM LAZARO: You mean they’re after the publicity?

AZIZ MEMON: Yes.Yes, sir, they’re after the publicity.

FRED DE SAM LAZARO: Who exactly is after the publicity?And what publicity do they want?

AZIZ MEMON: These Taliban groups — so, you know, this becomes quite an international news also.

FRED DE SAM LAZARO: In Karachi, workers we spoke to — paid about $5 a day — said they were undeterred.

MAN (through interpreter): The security situation is tough all over the country, but this is something we have to do for the children.

WOMAN (through interpreter): This disease cripples children, not just for a day but for their entire lives, and it affects the whole family.

WOMAN (through interpreter): This is important.As women health workers, it is our job to help kids.Polio teams are being attacked, but this is something we have to do.

FRED DE SAM LAZARO: They fanned out on this day across city neighborhoods, accompanied by armed policemen, though their presence has not stopped some attacks.

Difficult as it is for vaccinators to work in the cities, it’s becoming virtually impossible in the north and northwest of this country, near the Afghan border.Extremist militant leaders there have declared the polio campaign off-limits.

So, for now, the campaign has targeted buses to and from the no-go regions.Dr. Zaidi says this will, at best, contain polio, not wipe it out.To do that, she says, Pakistan’s military will need to take on the militants to allow vaccinators safe access.

ANITA ZAIDI: If you look at the number one problem of Pakistan right now is terrorism.I mean, polio is just a byproduct of this issue right now.The central issue is fighting terrorism, and if you address the security situation, the polio problem will automatically be addressed.

FRED DE SAM LAZARO: But there’s one more complication.We saw it in the slum: a seeming public indifference.

Even as they urged parents to bring children out to get the vaccine drops, even as people in this community introduced us to polio victims who live here, it’s clear many residents had other priorities.

Vaccinators say they got a little bit of resistance to the polio campaign, but they mostly got complaints.It’s about to rain, and their shelters are flimsy.There’s no clean drinking water, no sanitation, no schools.For millions of Pakistanis who live in conditions like these, polio is hardly the most pressing concern.

Some health professionals and political leaders also feel Pakistan has more pressing problems.After all, education, clean water, and sanitation would remove conditions that spread the polio virus.But those are long-term solutions.

Polio campaigners say getting simple drops to all children could wipe out the scourge much sooner and remove the stigma Pakistan endures internationally as one of the few exporters of the virus.But that would require resources and action, and no one is certain Pakistan’s government will make polio a top priority any time soon.

JUDY WOODRUFF: A version of Fred’s story aired on the PBS program “Religion & Ethics Newsweekly.”His reporting is a partnership with the Under-Told Stories Project at Saint Mary’s University in Minnesota.