Polio has spread to two more African countries that had been free of the crippling disease and threatens to become a major epidemic across west and central Africa, the World Health Organization said yesterday.
The disease begins reaching its high season next month.
The spread of polio to Guinea and Mali brings to 12 the number of previously polio-free African countries that have experienced an outbreak of the disease since January 2003. The spread deals a serious setback to the agency's efforts to eradicate the disease by year's end, a goal also hampered by a funding gap of $100 million.
But WHO, a United Nations agency based in Geneva, said it still believed it would eradicate polio, though it might take longer than expected.
WHO confirmed one polio case in Guinea, a child who became ill June 5, and two cases in Mali, in children whose symptoms began May 15 and July 5.
The agency also confirmed three additional cases in the Darfur region of western Sudan; all three children fell ill in July.
Guinea and Mali are outside a ring of countries that conducted synchronized polio vaccination programs last winter in an attempt to create an immunologic firewall to limit the spread of the disease from Nigeria and Niger.
Polio was last reported from Guinea in October 1999 and from Mali in January 1999.
Before the latest cases, WHO had planned additional synchronized vaccination programs in 22 countries, including Guinea and Mali, in October and November. The fall program aims to immunize 74 million children under the age of 5 years.
The outbreak originated in northern Nigeria where the government of the state of Kano had banned polio immunizations, WHO said. Religious and political leaders there had opposed immunization for a number of reasons, including belief that the vaccine made girls sterile and could spread HIV.
After tests performed independently showed no impurities or adulteration, Kano had lifted its ban on polio vaccine, leading to resumption of the immunization program late last month.
Dr. Bruce Aylward, global coordinator for the WHO polio program, said in a telephone interview from Geneva: "If there is to be any silver lining in this, it is that it shocked people out of the complacency that once Kano restarted immunizations our problems are solved.
"But the reality is we have a big epidemic in northern Nigeria. It is spreading and will continue to spread until we get a number of good immunization rounds in there."
Among the problems that health workers face as they try to wipe out polio is that routine immunization programs in affected countries fail to reach 50 percent of the target population.
"That raises the stakes in terms of how good the immunization campaigns need to be in October and November," Aylward said.
The need to conduct intensive immunization programs in a broader area of Africa is forcing WHO to spread its international consultants and technical workers more thinly, increasing the risks to the quality of the programs in key areas, Aylward said.
As of Aug. 24, there were 602 polio cases worldwide, of which 476, or 79 percent, are in Nigeria. Ninety percent of the world's cases are in Africa, where all but two countries - Nigeria and Niger - had been freed of polio by the end of 2002.
The number of polio cases might reach 1,000 this year in Nigeria, Aylward said, and it could take a full year of work to get it to zero.