The United Nations and South Sudan are taking extreme precautions to prevent any spread of Ebola from neighboring Democratic Republic of Congo, which is battling the second-biggest ever outbreak of the disease.

The U.N. and local authorities have made "a huge number of preparatory steps," including border-screenings, training health teams and bringing in vaccines for health-workers on the front-lines, the head of the U.N. mission in South Sudan, David Shearer, said Tuesday in an interview. An outbreak of the virus in Congo's restive east has killed almost 300 people since August.

"We all hope that it doesn't come close to South Sudan, but it's up to us to be prepared just in case the unlikely thing happens," Shearer said in the capital, Juba. He said the outbreak is "still not completely under control," but there's no indication it's an immediate threat to South Sudan, which is trying to emerge from five years of civil war.