CAIRO -- A yellow fever outbreak in Sudan's Darfur region has killed 107 people in the last six weeks, the World Health Organization reported Tuesday, warning that the disease could spread all over the country.

The number of deaths from the outbreak is steadily rising, and Sudan is working on an emergency vaccination drive. Officials reported last week that 67 people had died in the outbreak.

There is no medicinal cure for yellow fever, which is spread by mosquitoes. Doctors treat the main symptoms - dehydration, fever, bleeding and vomiting - and wait for the viral infection to pass.

The WHO estimates that more than 500 million people in 32 countries in Africa are at risk of yellow fever infection.

As part of the emergency response program, 2.4 million doses of the yellow fever vaccine are scheduled to arrive in the Sudanese capital next week, Dr. Anshu Banerjee of the WHO office in Sudan told the Associated Press by phone on Tuesday.

More than 350 suspected cases of yellow fever have been reported in Darfur since late September, and more than 30% of people showing symptoms have died, according to a WHO statement.

Around 70% are under 29 years old, according to a statement released Monday by the Sudanese Health Ministry and the WHO.

Banerjee warned that yellow fever cases are "definitely spreading" to new areas of the remote region of Darfur, where Sudan's government has been battling rebel groups since 2003. More than 300,000 people have been killed in the conflict, and health care services are not available to many residents as a result of the turmoil.

He said that while no yellow fever cases have been found outside Darfur, the WHO is planning a risk assessment in the next two weeks on the assumption that all areas in Sudan may be at risk of infection.

Banerjee said that Darfur's heavy rainy season this year created additional breeding sites for the disease-carrying mosquitos.

Sudan's last outbreak of yellow fever killed 160 people in the South Kordofan region in 2005.

Associated Press