Africa is on the brink of the biggest polio epidemic in years, with the crippling disease hitting Nigeria hard and re-emerging in Sudan's war-ravaged Darfur region, the World Health Organization said last week.
The number of polio cases globally has reached 333 this year, almost double the number for the same period last year. Total cases last year reached 783.
In Nigeria, where Muslim leaders have refused to participate in immunization programs, 257 cases have been reported this year.
"There is no question that the virus is spreading at an alarming pace," said David Heymann, M.D., who is overseeing the United Nations health agency's effort to eradicate the disease.
Polio usually infects young children, attacking the nervous system and causing paralysis, muscular atrophy, deformation and sometimes death.
Nearly 1,000 children in 125 countries were being infected daily by polio in 1988 when WHO and other health organizations launched the Global Polio Eradication Initiative.
That number dropped to 483 in 2001, and health officials declared the disease was eradicated in Europe, the Americas, much of Asia and Australia.
Epidemiologists now fear a major epidemic this fall, the start of the polio "high season." The disease has already appeared in nine sub-Saharan African countries, after being limited to only two at the beginning of last year.
"Right now we're at the end of the low season of polio," said Bruce Aylward, who coordinates the WHO polio initiative. "This is right when polio should be at its lowest level. It suggests that the virus is gathering steam to come roaring out."
WHO confirmed that a child was paralyzed by polio on May 20 in Darfur, the first case in Sudan in more than three years.
Health experts have long warned of epidemics in Darfur, where thousands have been killed and more than 1 million left homeless in a 15-month conflict between government-backed Arab militias and the black African Muslim population. The disease has also been found in previously polio-free Benin, Burkina Faso, Central African Republic, Chad and Ivory Coast. Botswana reported its first new infection in February. The U.N. agency said it urgently needs $25 million to launch a vaccination campaign across 22 African nations in October.