Despite a 19-year campaign, outbreaks of polio continue to crop up, sometimes because of strains that mutate from the oral Sabin vaccine commonly used, The Washington Post (NYSE:WPO) reported Tuesday. Eventually, experts say it will be necessary to switch to the Salk vaccine, which doesn't use live virus to achieve immunity, the newspaper said. However, that form of vaccine is more costly -- about $2.70 per dose, compared to 15 cents for the Sabin version.

Worldwide, polio's annual toll reached 2,000 last year after having fallen to 784 in 2003, the Post said.

However, a $100 million donation by the Bill and Melinda Gates Foundation, which requires a match by Rotary International, has infused energy into the effort.

"I sense great enthusiasm" for a renewed push to eradicate polio, said Robert Scott, a physician who heads Rotary's effort to halt the disease.

R. Bruce Aylward, a Canadian physician who directs the eradication initiative at the World Health Organization in Geneva, said agrees. "I have been in this a long time, and this is the first time I have seen an oversight committee say, 'This is going to be finished,' " he said.