A new outbreak of Ebola virus has hit the Democratic Republic of Congo, just days after the last outbreak was declared over.

Four cases have been positively identified and more are likely, Congo’s health minister, Dr. Oly Ilunga Kalenga, said in a statement Wednesday.

“Just a week after announcing the end of the ninth epidemic of Ebola virus disease in the Equator Province, the Democratic Republic of Congo is facing a new epidemic," Kalenga said. He added that there was no indication that the two most recent outbreaks, separated by more than 1,500 miles, are related.

More than 50 people were infected in the most recent outbreak and 33 died, according to Congolese officials.

The health ministry has been checking into reports of viral hemorrhagic fever in North Kivu Province, in the northeastern part of the vast Central African nation, since last weekend. Twenty people have died and 26 people have symptoms that could indicate any number of viral infections, including Ebola.

“Of the six samples analyzed, four were positive for Ebola virus,” Kalenga said.

It’s the third outbreak in just over a year in Congo. This time, the country could be ahead of the game. Thousands of doses of vaccine were shipped to the country during the last outbreak and the health ministry geared up to test samples, educate people about the spread of the virus and get experts to the site of the outbreak quickly.

“Although we did not expect to face a 10th epidemic so early, the detection of the virus is an indicator of the proper functioning of the surveillance system put in place by the General Directorate for Disease Control,” Kalenga said.

Outbreaks of Ebola have occurred regularly in Central Africa since the virus was first identified in 1976, but none has ever been as serious as the 2014-2016 epidemic, which killed 11,000 people in Liberia, Sierra Leone and Guinea in West Africa.

“Since we are coming out of another Ebola outbreak, we have kept staff and equipment in place,” Dr. Matshidiso Moeti, WHO Regional Director for Africa, said in a statement.

“This allows us to have a head start in response to this cluster.”

The area affected is on a lake and near the borders of Uganda and Rwanda, which raises the possibility of international spread. WHO says more than 1 million displaced people, who have fled war and unrest, live in the region.