At least 10 people in the province had died from suspected Ebola by 20 August, according to the UN World Health Organization (WHO), which first reported the outbreak on 17 August. Local sources say the first symptoms were spotted about a month ago.
Nine of the deaths - which included three health workers - occurred in the district of Isiro, and one occurred in Dungu District. WHO reports a total of 15 cases so far, 13 probable and two confirmed.
"The death case we got in Dungu was a hunter. Once in the bush he saw a dead antelope and did not care to ask why it had died. He immediately took [the carcass] and went to eat it... He fell sick and passed away," said the DRC's Health Minister Kabange Numbi.
Bushmeat - the meat of wild animals, including hoofed animals, primates and rodents - is often the main source of animal protein available to people in parts of the DRC. It is also a livelihood source for people in the Congo basin, according to a 2011 paper by the Center for International Forestry Research.
According to WHO, "Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals." Fruit bats are considered to be the natural host of the virus.
"Ebola virus is an animal disease, and when people are having contact with animals in bushes, as people some in parts of our country rely on bush meat for their livelihood... and don't care to avoid eating meat they've got from dead animals that they often find in bushes [they risk contracting the disease]," said Mondoge Vitale, head of disease control at WHO's Kinshasa office.
The strain of Ebola in the Congo has been identified as Ebola-Bundibugyo - named for a Ugandan district that borders the DRC. The western district of Kibaale in neighbouring Uganda was recently hit by an outbreak of another strain, Ebola-Sudan, which killed at least 16 people.
There is no vaccine for the highly infectious disease, which causes fever and bleeding from orifices and can cause death within days. The fatality rate for the Bundibugyo strain is estimated at about 40 percent.
Contingency measures have been put in place to contain the outbreak. The health ministry has established national- and district-level taskforces and is working with partners, including the NGO Médecins sans Frontières (MSF), the United States Centers for Disease Control and Prevention (CDC), the UN Children's Fund (UNICEF) and WHO.
"The measures include the sensitization of the communities, protection of health workers - in the zone where the outbreak has been declared they have been given protection equipment... We have beefed up the screening at Kisangani Port [a commercial hub in Orientale Province] to watch the outbreak across the Congo River toward the capital, Kinshasa," said Numbi. "[We are also] reinforcing screening at Kisangani Airport for passengers coming and going out it to other countries’ airports."
Orientale Province borders the Central African Republic, South Sudan and Uganda. South Sudan is already on high alert following the outbreak in neighbouring Uganda.
MSF has deployed experts to set up isolation facilities and surveillance systems in affected areas, but officials say their work is being hampered by a lack of information. "As long as the surveillance system is not properly enforced, we are not sure whether we may have missed some cases who have not been in contact with health facilities," said Olympia de la Rosa, a health adviser in MSF's Emergency Unit.
The DRC has experienced several fatal Ebola outbreaks in the past. In 1976, at least 280 people died from the Ebola-Zaire strain, which killed another 250 people in 1995 and 187 in 2007, according to the CDC.