Two of the patients later died, while the third returned to the centre in the city of Mbandaka.
"It is unfortunate but not unexpected", he said.
"WHO and partners are working together to rapidly scale up the search for all contacts of the confirmed case in the area".
"We're on the epidemiological knife edge of this response", he added at the United Nations body's annual assembly.
The NICD says it will be assisting World Health Organization in dealing with the Ebola outbreak investigation for now from South African shores. Many of them follow religious and traditional practices, especially during funerals, which are not necessarily aligned with health recommendations.
Access there and to nearby Iboko is hard and efforts are still ongoing to put in place a so-called "cold chain" to maintain Ebola vaccine at between minus 60 and minus 80 degrees Celsius.
Health Ministry sources, who asked not to be named, said two police officers had been deployed to help track them down. The trial will not expose participants to the Ebola virus.
Some people are refusing medical care and turning to preachers and prayers to chase away the threat.
Ebola virus spreads through direct contact with either bodily fluids or objects contaminated by someone ill with the disease, according to the US Centers for Disease Control and Prevention. Symptoms include fever, headache, fatigue, muscle pain and, as the disease worsens, it can cause vomiting diarrhea, rash and bruising or bleeding without an injury.
There are several kinds of hemorrhagic fever in the Democratic Republic of Congo, the country's health ministry has noted; thus, not all suspected cases are necessarily Ebola.
Latest data from health authorities in the DRC, indicates a total of 52 cases of Ebola in the north-west of the country; 31 of these are confirmed, 13 are probable and eight are suspect.
Health officials are scrambling to contain an outbreak of the deadly disease in the heavily populated port city in northwest Congo that is believed to have killed 22 people since April. The goal is to "build rings" around confirmed Ebola cases to halt the spread, he said.
"The plan consists of surveillance, case investigation, contact tracing, case management, safe burials, community engagement, and social mobilization", the statement said.
Dr. Matshidiso Moeti, the WHO regional director for Africa, said the nine countries bordering Congo have initiated preparedness activities, which includes training health care workers and supplying clinics.
The health minister did not immediately respond to ABC News' request for comment today about the patients' escaping quarantine in Mbandaka.
Officials said the Central African Republic and the Republic of Congo are in the most danger, because they sit along major river routes that emanate from the epicenter of the outbreak in the northwestern Equateur Province.
Health officials are particularly concerned by the disease's presence in Mbandaka, a crowded trading hub upstream from the capital Kinshasa, a city of 10 million people. Just across the river from Kinshasa is Brazzaville, the capital of the neighboring Republic of the Congo.
"If we're lucky and the disease doesn't spread, the outbreak will be quickly resolved and we will have to use few experimental products", Annick Antierens of Médecins Sans Frontières tells Nature.