Polio cases are at an all-time low worldwide, following its eradication in India last year, raising hopes but also fears about a threat of resurgence especially in sub-Saharan Africa unless remaining reservoirs of polio virus are stamped out.

Conflict and insecurity is preventing health workers from reaching hundreds of thousands of children in Afghanistan and Pakistan with doses of polio vaccine, health ministers said.

"The number one issue is security-compromised areas, insecure areas such as in the tribal areas which is still giving us several (polio) cases and is a big challenge for us," said Shahnaz Wazir Ali, Special Assistant to Pakistan's Prime Minister, who is in charge of the polio eradication campaign.

"Religious leaders have been very actively mobilized," she told a news briefing held during the annual ministerial meeting of the World Health Organization (WHO).

Some 22 top Islamic scholars from around the world have signed an endorsement of the polio eradication program, which is being used to persuade Pakistani parents, Wazir Ali said.

"This should put to rest some of the misapprehensions and reservations in the minds of certain areas of the population in Pakistan. We feel this has been quite effective," she said.

"In other words, these endorsements here categorically say that Islam does not in any way, form or manner prevent intake of the oral polio vaccine and that the oral polio vaccine being given to the children is endorsed by them and is fully safe."

Polio attacks the nervous system and can cause irreversible paralysis within hours of infection. But it can be stopped with comprehensive, population-wide vaccination.

When a global eradication campaign was launched in 1988, it paralyzed more than 350,000 children in 125 countries annually.

Despite huge progress over the decades, polio outbreaks in China, Chad, Democratic Republic of Congo and Niger last year were the latest setbacks to the program.

Four countries - Afghanistan, Chad, Nigeria and Pakistan - have reported 60 cases so far this year, against 153 in 12 countries at this time last year, according to the WHO.

"TIPPING IN RIGHT DIRECTION"

"There is some evidence that things are tipping in the right direction already," Bruce Aylward, the WHO's top official for polio eradication, said. "We've crossed a rubicon."

Nigerian Health Minister C.O. Chukwu said: "We have other health challenges. But this one is very vital because the world is virtually at the end of eradicating polio and there's no reason why Nigeria should be one of those delaying the world.

"We're recruiting religious leaders and traditional rulers," he said. The Federation of Muslim Women's Associations in Nigeria, a "formidable group", is also backing the campaign.

Polio is still entrenched in eight states in predominantly Muslim northern Nigeria. Vaccination campaigns were suspended across the north in 2003/04 after some state governors and religious leaders alleged the vaccines were contaminated by Western powers to spread sterility and HIV/AIDS among Muslims.

The porous Afghan-Pakistan border remains a huge challenge.

"We do believe that Afghanistan and Pakistan is one epidemiological block in terms of polio. We believe the success in one country is closely dependent on action in the other," said Mohammad Taufiq Mashal, Director General of Preventive Medicine at Afghanistan's health ministry.

It is not the first time that the world has come tantalizingly close to wiping out the crippling disease.

"We're so close, there is no time for complacency," Dr. Christopher Elias, head of global development at the Gates Foundation, a major donor, told Reuters in Geneva.

(Reporting by Stephanie Nebehay; Editing by Michael Roddy)

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