The United Nations Refugee Agency (UNHCR) fears the Ebola epidemic could spread to South Sudan due to the influx of Congolese refugees.
In its weekly brief, the agency said it had received at least 42 DR Congo nationals who crossed into country to South Sudan recently.
But it did not mention whether the 42 were Ebola free or not.
The agency said it conducted sensitisation among the refugees on Ebola prevention in South Sudan's Yei River State, where the Congolese new arrivals were hosted.
"In Yei, UNHCR and partners conducted community sensitisation and awareness sessions on Ebola Virus Disease (EVD). The key messages focused on the transmission, prevention and the importance of high vigilance on arrivals from the Democratic Republic of Congo to 42 (11 men and 31 women) members of the community," it says.
The sensitisation, UNHCR went on, was done mostly in churches on weekly basis.
The target areas were Lomi, Kukuyi, and Yago in Yei.
Juba health authorities recently declared restrictions on border movement between DRC and South Sudan over the Ebola fears.
Juba also deployed health emergency response teams to the border to screen Congolese nationals entering the country.
DRC has since the beginning of the year grappled with several Ebola outbreaks.
Ebola is one of the world's most notorious diseases, being both highly infectious and extremely lethal.
It is caused by a virus that has a natural reservoir in the bat, which does not itself fall ill, but can pass the microbe on to humans who hunt it for "bush meat".
The virus is handed on by contact with bodily fluids — touching a sick or dead person is a well-known source of infection.
The worst-ever Ebola outbreak started in December 2013 in southern Guinea before spreading to two neighbouring West African countries, Liberia and Sierra Leone.
That outbreak killed more than 11,300 people out of nearly 29,000 registered cases, according to WHO estimates, although the real figure is thought to be significantly higher.