Three new cases were recorded in the Bikoro area and two in Wangata, the national health ministry said in a statement. Both lie in the northwestern province of Equateur.
DRC and the UN World Health Organisation are rushing to contain the outbreak that has sickened more than 50 people in recent weeks, with 25 dead.
The outbreak was first declared on May 8 in Bikoro, a remote area in the rural northwest of the vast central African country.
Medical charity Medecins Sans Frontieres opened a new treatment centre in Mbandaka, the capital of Equateur province, an AFP reporter saw. At least three people were taken in there on Friday for treatment.