A two-year-old girl has contracted polio in Ethiopia in another sign that the epidemic is spreading across Africa, the World Health Organization (WHO) said on Friday.

It was the 14th previously polio-free country to record an imported case, including 13 in Africa, posing a fresh setback to the United Nations campaign to halt transmission of the crippling virus by year-end.

WHO officials say the virus originated in Nigeria 18 months ago, after the northern state of Kano suspended vaccinations, and has traveled east as far as Sudan and Saudi Arabia.

“The (Eritrean) Ministry of Health team has reported back that they have seen the first case and are looking at another suspect case today,” Bruce Aylward, coordinator of the WHO’s global polio eradication initiative, told a news briefing.

“This virus will move relentlessly forward unless it is stopped with high-quality (immunization) campaigns. There is a big risk of further spread if these aren’t successful,” he said.

The confirmed case - the first is Ethiopia in four years - and the suspected cases occurred in different areas of Tigray province close to Sudan’s border, WHO officials said.

It coincided with a mass synchronized immunization drive starting this weekend in 22 countries across the continent which aims to reach 100 million children under age five.

David Heymann, head of the WHO eradication program, said: “In Africa, it is a setback, but the population is less dense than in Asia and there is a will there to really do the campaign in every country.”

The number of new cases rose 50 percent worldwide to 1,185 last year, largely because of the continuing spread in Nigeria.

Africa’s polio epidemic erupted after a 10-month halt in immunization in Kano where Muslim elders said the vaccines were part of a Western plot to spread HIV and infertility, according to WHO officials.

Nigeria, Africa’s most populous country, recorded 763 cases in 2004, accounting for two-thirds of the toll. It resumed immunization last July.