By Susan Scutti, CNN

(CNN) -- Ebola virus disease has sickened 150 people and caused the deaths of at least 69 people in the Democratic Republic of Congo's northeastern region, the nation's Ministry of Health reported Monday.

Of these 150 cases, 119 have been confirmed and 31 are probable. An additional 31 deaths have occurred among probable and suspected cases, which would bring total Ebola deaths to 100 once confirmed. Forty-one people have recovered, according to the ministry.

"We have passed the sad mark of 100 deaths," Dr. Peter Salama, WHO deputy director-general of emergency preparedness and response, said Tuesday. "The response is facing a series of grave obstacles."

After weeks of control efforts having made impact, Salama expressed concern the outbreak could now worsen due to attacks in the region, movement of people and distrust in the community.

"We are now extremely concerned that several factor may be coming together over the next weeks to months to create the potential perfect storm," he said, outlining the harms of "active conflict limiting our ability to access civilians, distrust by a community, already traumatized by decades of conflict and of murder, driven by a fear of a terrifying disease but also exploited and manipulated by local politicians prior to an election."

Parts of the local population are refusing treatment because of distrust and superstitions, he said.

A violent clash in Beni on Sunday, attributed to the Alliance of Democratic Forces, led to the death of at least 21 people, including 17 civilians, according to Salama.

"The response at this stage is at a critical juncture," he said. "We have seen an increased frequency and increased severity of attacks by armed opposition groups in recent weeks."

In a tweet, Salama communicated that the Ebola response teams in the city of Beni were on lockdown beginning Sunday.

Those on lockdown include the teams that distribute vaccinations, those who track family, friends and others who came in contact with those infected, and those who educate the public by working directly with the community. In its daily report, the Ministry of Health stated that "many residents of the city of Beni took to the streets on Sunday to protest the growing insecurity in the area." The Ministry added that field activities will resume "as soon as calm returns to the city."

This suspension of activity in Beni was addressed by Dr. Oly Ilunga Kalenga, Minister of Health, in a separate statement posted Monday.

"All the pillars of the response remain fully operational," he wrote. He specified that the Beni Ebola Treatment Center remains open to patients, vaccinations continue and free health care remains available at approved centers, including to victims of violence.

Teams of health care personnel in areas outside Beni are continuing to conduct field work, including providing vaccinations, according to WHO.

But "80% of people that are at risk of Ebola, at direct and immediate risk, were unable to be followed up yesterday in Beni," Salama said Tuesday.

'Wide geographical spread'

The North Kivu province is the epicenter of the outbreak, though some cases have been reported in neighboring Ituri province as well, according to WHO. Together, the two provinces, which are among the most populated in the nation, border Uganda, Rwanda and South Sudan.

Congo is concurrently experiencing a long-term humanitarian crisis that includes intermittent armed conflict, according to WHO. As a result, other health epidemics, including cholera, measles and polio, as well as human trafficking, are flourishing there.

More than 1 million internally displaced people are in North Kivu and Ituri, according to WHO; the movement of refugees through and out of the provinces is a potential risk factor for spread of Ebola.

In a tweet posted Monday, Salama stated that a case in Tchioma, an area of Congo that borders Uganda, "raises concern about further spread."

On Tuesday he explained "this case is very close to the Kasen airport on the the riverbanks of lake Albert which has of course direct connectivity across the lake to Uganda. That area is entirely surrounded by a different rebel group...We are dealing now with 3 active armed opposition groups."

Public health teams are also investigating nine suspected cases not included among the 150, the ministry reported.

"We now have wide geographical spread of Ebola," said Salama. "Into red zones, into border areas with surrounding countries such as Uganda."

On average, Ebola kills about half of those infected, but case fatality rates in individual outbreaks have varied from 25% to 90%.

Ebola, which causes fever, severe headache and in some cases hemorrhaging, most commonly affects people and nonhuman primates, such as monkeys, gorillas and chimpanzees. This is a second, separate outbreak that has occurred in Congo so far this year, according to the World Health Organization. A previous outbreak, which began in May and ended in July, affected a western region of the country where 54 cases of Ebola virus were recorded, including 33 deaths.

Beginning with the 1976 discovery of Ebola in an area that is now the Democratic Republic of Congo, the country has experienced 10 outbreaks, including this year's outbreaks.

Thousands vaccinated

Since August 8, the Ministry has been inoculating people at high risk of an Ebola infection: primary and secondary contacts of those with confirmed Ebola infections.

More than 11,700 people have now been vaccinated, according Salama, who described this as "the largest scale we have ever seen of the use of Ebola vaccine in the midst of a response."

Despite the successful Ebola vaccine campaign, WHO encountered some community resistance in a small village, Ndindi, surrounding the city of Beni. Ndindi has been responsible for a large number of Ebola cases over the last few weeks.

The experimental rVSV-ZEBOV vaccine, made by pharmaceutical company Merck, proved highly protective against the deadly virus in a major trial in Guinea, according to WHO.

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. In some cases, the virus is spread from contact with someone who has died from the disease. The virus enters the body through broken skin or mucous membranes in the eyes, nose or mouth. People can get it through sexual contact, as well.

"Beyond the medical response, the only way to end the Ebola Virus Disease epidemic remains the mobilization and commitment of the community alongside the health authorities," Kalenga said in a statement.

Salama called for continued response from the International Community to ensure provinces and countries are prepared.

"We call on governments In surrounding countries to accelerate their preparedness, which they have begun, to ensure that if - as is increasingly possible - this outbreak spreads across international borders we are all collectively prepared to top it before it gets out of control," he said.