The world is closer than ever to eradicating polio. When the effort began in 1988, the disease was endemic in 125 countries. Just three remain: Nigeria, Pakistan and Afghanistan.

In recent months, there have been fewer cases in fewer districts of fewer countries than at any time in history.

Polio is a highly infectious disease that can lead to paralysis. It largely strikes children 5 years old and younger, but there have been more cases involving adults in recent years, with higher lethality. Obliterated in the United States 30 years ago, polio has proved a stubborn foe elsewhere.

The potential benefits of wiping out polio are improved lives for millions of children. Yet eradicating diseases is immensely difficult. So far, the campaign against smallpox stands as the only success.

There was long concern that if the transmission of polio could not be halted in India, eradication would be impossible. But India has been free of polio since January 2011. Also, a more effective oral vaccine is targeting the two most prevalent strains of the virus.

On May 26, the World Health Organization declared polio eradication a "programmatic emergency." The idea is to galvanize work in the remaining polio-infected areas of Nigeria, Pakistan and Afghanistan. All three nations suffered alarming spikes in cases last year, and the goal of delivering oral vaccine to every child is up against the formidable obstacles of war, corruption, weak public health systems and widespread migration. This appears to be another make-or-break moment.

A renewed campaign will be costly. The Global Polio Eradication Initiative, set up in 1988 by the WHO, UNICEF, the Centers for Disease Control and Prevention (CDC) and Rotary International, says that it needs an additional $945 million for a total budget of $2.19 billion this year and next. For the current fiscal year, the United States has boosted support to $151.1 million, up $17.6 million over last year.

Rotary International has exceeded its goal to raise more than $200 million to match a $355million challenge grant over several years from the Bill and Melinda Gates Foundation. The CDC has made polio a top priority; it put some 90 people to work on it every day in its emergency operations center. These examples and the urgency of the cause will hopefully inspire other donors around the world to fill the budget gap.

Stamping out polio is not a sure thing, but this may be the best chance in a generation. It should not be missed for lack of resources.