LONDON (AP) -- For the first time ever, the World Health Organization on Monday declared the spread of polio an international public health emergency that could grow in the next few months and unravel the nearly three-decade effort to eradicate the crippling disease.
The agency described current polio outbreaks across at least 10 countries in Asia, Africa and the Middle East as an "extraordinary event" that required a coordinated international response. It identified Pakistan, Syria and Cameroon as having allowed the virus to spread beyond their borders, and recommended that those three governments require citizens to obtain a certificate proving they have been vaccinated for polio before traveling abroad.
"Until it is eradicated, polio will continue to spread internationally, find and paralyze susceptible kids," Dr. Bruce Aylward, who leads WHO's polio efforts, said during a press briefing.
Critics, however, questioned whether Monday's announcement would make much of a difference, given the limits faced by governments confronting not only polio but armed insurrection and widespread poverty.
"What happens when you continue whipping a horse to go ever faster, no matter how rapidly he is already running?" said Dr. Donald A. Henderson, who led the WHO's initiative to get rid of smallpox, the only human disease ever to have been eradicated.
The WHO has never before issued an international alert on polio, a disease that usually strikes children under 5 and is most often spread through infected water. There is no specific cure, but several vaccines exist.
Experts are particularly concerned that polio is re-emerging in countries previously free of the disease, such as Syria, Somalia and Iraq, where civil war or unrest now complicates efforts to contain the virus. It is happening during the traditionally low season for the spread of polio, leaving experts worried that cases could spike as the weather becomes warmer and wetter in the coming months across the northern hemisphere.
The vast majority of new cases are in Pakistan, a country which an independent monitoring board set up by the WHO has called "a powder keg that could ignite widespread polio transmission."
Dozens of polio workers have been killed over the last two years in Pakistan, where U.S. forces located Osama bin Laden using information gained in part under the guise of polio vaccinations. A Pakistani doctor, Shakil Afridi, is currently jailed for his role in the CIA operation that uncovered the al-Qaida leader's hideout. Afridi was involved in a vaccination ruse that led to bin Laden's death and eroded trust in polio programs among many Pakistanis.
At the end of April, there were 68 confirmed polio cases, compared with just 24 at the same time last year. In 2013, polio reappeared in Syria, sparking fears the civil war there could ignite a wider outbreak as refugees flee to other countries across the region. The virus has also been identified in the sewage system in Israel, the West Bank and Gaza, although no cases have been spotted.
In February, the WHO found that polio had also returned to Iraq, where it spread from neighboring Syria. It is also circulating in Afghanistan (where it spread from Pakistan) and Equatorial Guinea (from neighboring Cameroon) as well as Nigeria, Ethiopia, Somalia and Kenya.
Officials also worry countries torn by conflict, such as Ukraine, Sudan and the Central African Republic, are rife for polio reinfection.
Some critics say it may even be time to accept that polio may not be eradicated, since the deadline to wipe out the disease has already been missed several times. The ongoing effort costs about $1 billion a year.
"For the past two years, problems have steadily, and now rapidly mounted," Henderson said in an email. "It is becoming apparent that there are too many problems (for the polio eradication effort) to overcome, however many resources are assigned."
Henderson and others have suggested the extraordinary efforts needed for polio eradication might be better spent on other health programs, including routine vaccination programs for childhood diseases. But he conceded that transitioning to a control program would be difficult. "If not eradication, how does one accomplish a 'soft landing' which could sustain the global program on immunization?" Henderson said.
Aylward said the WHO and its partners, including the U.S. Centers for Disease Control and Prevention, aren't yet considering pushing back their latest deadline to eradicate polio by 2018.
CDC Director Dr. Tom Frieden said the reemergence and spread of polio out of Pakistan, Cameroon and Syria pose "a serious threat to our ability to eradicate polio."
"Conflicts in many areas where polio is circulating are hampering efforts to vaccinate but success remains within reach," Frieden said.
Still, the independent board monitoring the progress being made on polio has called for overhauling the program.
"Few involved in (polio eradication) can give a clear account of how decisions are made," concluded a recent report by the group. "If a billion-dollar global business missed its major goal several times, it would be inconceivable that it would not revisit and revise its organizational and decision-making structure."
AP Medical Writer Mike Stobbe contributed to this report from New York.