The virus is spread by mosquitoes and the disease is untreatable. WHO said in an outbreak about 20 percent of the population is likely to get the disease, with half of them dying.
WHO says that $806,000 would be sufficient to vaccinate 650,000 people, the U.N. Integrated Regional Information Network said.
"The most important thing is to do an investigation, and then to vaccinate all the population in the immediate zone," Kone Souleymane, a WHO spokesman in Ivory Coast, said. "Then, there must be a wider vaccination of other people who may have come into contact with the infection."
Yellow fever has been making a comeback in Africa even though an effective vaccine has been available for 60 years. The early symptoms resemble malaria. People with the disease then either recover or relapse with jaundice, bleeding from eyes, nose and mouth, kidney failure and death.