The World Health Organization says that despite a global effort to eradicate polio by the end of 2005, the number of cases rose by almost 30 percent last year.

Organization officials say more than 1,170 cases were reported last year compared to 784 in 2003. Ninety percent of the incidents occurred in Nigeria, India and Pakistan.

Nigeria, Africa's most populous country, accounts for 65 percent of the 2004 total. Eradication efforts have been hampered by a months-long vaccine boycott in that country's northern region. Opponents there had said the polio vaccine was contaminated with infertility agents.

That boycott led to the spread of the virus to neighboring countries, including Ghana, Benin, Chad and Togo. Conflicts in Ivory Coast and Sudan also have hindered eradication efforts.

Polio is a disease that attacks the nervous system, causing paralysis, muscle atrophy and sometimes death.

Some information for this report provided by AP.