DAKAR, Senegal - Authorities have confirmed an Ebola case not far from Congo's border with South Sudan, a country with a weak health care system after years of civil war that is vulnerable to the potential spread of the deadly disease.

The 40-year-old woman had travelled nearly 500 kilometres (289 miles) from Beni, despite having been identified by health officials as having been exposed to Ebola and warned not to travel.

Her case was confirmed in Ariwara, Congo, about 70 kilometres (43 miles) from the border with South Sudan's Yei River State, according to a report from South Sudan's health ministry that was viewed Tuesday by The Associated Press.

It is the closest confirmed case to South Sudan since the outbreak began in Congo last August, according to an official with close knowledge of the outbreak who spoke on condition of anonymity as they were not authorized to speak on the record.

People who have come into contact with Ebola patients are supposed to be monitored for 21 days, the incubation period during which symptoms can emerge after exposure. Long-distance travel, particularly to regions bordering other vulnerable countries, is not recommended.

More than 1,500 people have died in Congo since the epidemic began, and two other fatal cases were reported in Uganda after a family sickened in Congo returned home across the border. While no other fatalities have emerged since the scare, fears remain high that Ebola could spread through the impoverished region where people are often mobile and difficult to trace.

While authorities in South Sudan have been preparing for possible spread of Ebola case across the border, the country still remains far less prepared than Uganda. A five-year civil war in South Sudan has killed nearly 400,000 people and the health system is weak.

Contact tracing is critical to stopping the disease's spread, but those efforts in South Sudan would be complicated by the fact more than 4 million people have been displaced by the war. Medical facilities, which were already far more basic than those in Congo or Uganda, have been further weakened during the conflict.

The outbreak is now the second deadliest in history, surpassed only by the 2014-2016 epidemic in West Africa that caused more than 11,300 deaths. While there is an experimental vaccine that has shown a high level of protection, efforts to vaccinate people in eastern Congo have been complicated by instability.

The region where the outbreak began has been plagued for decades by violence from rebel groups and armed militias. The population remains highly distrustful of the Congolese government and the health authorities now trying to fight the disease. Major international health charities have had to curtail their work following deadly attacks on treatment centres and assaults on health teams in the field.