Sudan has launched a massive vaccination effort to combat yellow fever in an attempt to stem its massive outbreak, the United Nations says.

The country has been hit by a massive outbreak of yellow fever. According to Chinese news source Xinhua, the death toll has risen to 150 from the disease in just a few short weeks.

The country is attempting to vaccinate 2.4 million people who are considered at risk for the disease in Darfur.

Officials from the UN's Office for the Coordination of Humanitarian Affairs report that a shipment of 800,000 doses on Friday was received in Khartoum by the Health Ministry.

The disease outbreak has been said to have taken place since September. As of November 11, a World Health Organization press report says that 329 people have been infected with the disease, though the Associated Press says that number has risen to a suspected 459 cases as of Saturday.

The outbreak is believed to have been caused by the country's particularly heavy rain season. The weather created additional hotspots for infected mosquitoes to breed.

The outbreak has occurred in Greater Darfur, according to the World Health Organization. Darfur was the site of an extensive conflict between the government and rebel groups. Over 300,000 people have been killed since 2003, when the conflict is considered to have started. As a result, many health care services are not available in the region.

Yellow fever is a disease transmitted by infected mosquitoes. The disease, which is endemic in many parts of Africa and Latin America, is believed to kill 30,000 people a year. The disease is characterized by subtle symptoms at first, like fever, headaches, and loss of appetite. For an unfortunate 15 percent of infected cases, the disease moves on to more severe symptoms, like jaundice and bleeding from the mouth, eyes, nose, and feces; kidney failure can occur. The disease is oftentimes misdiagnosed as malaria, hepatitis, or poisoning.

There is no cure for yellow fever, but the vaccine is considered highly effective. The vaccine can provide protection for up to 35 years.