The outbreak of the Bundibugyo strain of Ebola, for which there is no tested vaccine or treatment, has infected 1,307 people and killed 377 in the Democratic Republic of Congo since being declared on May 15, the government says, Reuters reported.
A much smaller number of cases have been reported in Uganda and experts warn of the possibility of it spreading to other neighbors, such as South Sudan.
"If we have the resources and we step up, we can contain this outbreak and prevent further losses," said Damien Mama, United Nations Development Programme resident representative in Congo.
"If we do not, this health emergency risks becoming a much deeper and prolonged development crisis across the region and potentially the continent."
The UNDP outlined three scenarios for the outbreak. In the best scenario, where the epidemic remains contained in the two countries, the cost is $1 billion for Congo's GDP, the report said.
In the worst-case scenario, the disease spreads to countries including Rwanda and Angola and coincides with higher fuel costs linked to the Iran crisis, cutting continental GDP by $3.6 billion and resulting in 328,000 job losses, the report said.