Nigeria's health authorities reported a surge in polio cases Thursday, saying the number of infections so far this year is double the total from all of last year.

The World Health Organization began a global immunization drive in 1988 in hopes of eradicating the disease. But its spread has continued in parts of Nigeria, where authorities in the mostly Muslim north ordered an immunization boycott in 2003, claiming the vaccine was part of a U.S.-led plot to render Muslims infertile or infect them with AIDS.

Nearly 90 percent of the new infections were reported in Nigeria's north, Educe Ababa, a top health official, told reporters in the capital, Abuja.

She said Nigeria has recorded 467 polio infections in the first months of 2006, compared with 224 new cases for the whole of 2005.

CountryWatch: Nigeria

Ababa said that while Nigeria won't be able to halt the disease's spread this year, it could be brought under control in the north.

The Geneva-based WHO failed to meet its long-standing target of eradicating polio globally by the end of last year.

Vaccination programs restarted in Nigeria in 2004 after the 11-month boycott. But the delay effectively set global eradication efforts back at least a year, and the boycott was blamed for causing an outbreak that spread the disease across Africa and into the Middle East.

WHO now has set a target for eradicating the disease in 2007.

Last year, 1,889 people were infected with polio worldwide, 775 of them in Africa, according to WHO. Polio is still classified as endemic in Afghanistan, India, Nigeria and Pakistan, and has recently been stamped out in Egypt and Niger.

Polio is spread when people — mostly children under 5 — who are not vaccinated come into contact with the feces of those with the virus, often through water. The virus attacks the central nervous system, causing paralysis, muscular atrophy and deformation and, in some cases, death.