An outbreak of the deadly Ebola virus in a turbulent region of the Democratic Republic of the Congo may last as long as two years in the absence of a stronger international response, senior global public health officials said this week.

But there are some limited signs of hope that the virus is infecting fewer people in the provinces of North Kivu and Ituri, after a disastrous few months in which the number of cases spiked dramatically in the midst of flaring violence.

At least 2,031 people have been infected with the Ebola virus since the outbreak began 10 months ago, according to the Congolese Health Ministry, and 1,367 people have died.

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“This outbreak is not under control at this time,” Centers for Disease Control and Prevention director Robert Redfield told the House Foreign Affairs Committee this week. He said the virus could rage in Congo for as long as two years.

Speaking to reporters Thursday in Geneva, Michael Ryan, overseeing the response for the World Health Organization (WHO), agreed.

“In a worse case scenario, I can definitely develop a scenario where this is going to take another year or two years,” Ryan said. “At this point, the outcome is effort-related. Are we prepared to make the immediate, sustained, comprehensive effort to bring this disease under control?”

Global health care officials worry, too, that stockpiles of a new vaccine manufactured by Merck & Co. that has proved efficient in preventing transmission are running low.

More than 130,000 people in the region have been vaccinated, including health care workers, those who have been in contact with an Ebola victim and contacts of those contacts. But WHO recently cut the recommended dose of the vaccine, a reflection of the fact that global supplies are limited.

“Vaccine supply is limited, and there’s a need to accelerate that supply,” Redfield told Congress. “We do project that we are going to run out of vaccine before we get adequate vaccine.”

The number of cases has increased by about 150 in the past two weeks, a much slower growth rate than the previous month, when security incidents and attacks on health care workers slowed or halted the response.

The last major attack claimed the life of a World Health Organization doctor treating Ebola-infected patients in the city of Butembo.

“It’s very early to make any conclusions. We want to make sure we can have access to all communities for active surveillance to make sure we’re not missing cases,” Ibrahima Socé Fall, the WHO’s regional emergencies director in Africa, said in an interview. “The last days or weeks have been quiet.”

The prospects for violence still exist. On Monday, a diagnostics laboratory in the town of Komanda was robbed, though no one was hurt. Also on Monday, rebels raided a neighborhood in the city of Beni, in an attack unrelated to the virus that killed a dozen people.

“We’re certainly seeing a huge benefit from a period of relative calm that has existed over the last six weeks,” Ryan said. “Our continued fear is further violence that would disrupt any operations in the field.”

But global health officials worry the virus continues to spread out of sight. The official case and death figures may undercount the number of victims by as much as a quarter, as families try to nurse their relatives back to health rather than seeking treatment.

Less than a quarter of recent cases have come from those who are known contacts of previous victims, Redfield told the House committee. That indicates a large proportion of the transmissions between infected people are occurring outside of the view of health officials responding to the virus.

“We are definitely missing cases, because when you have community deaths like that and probable cases, you are missing transmissions,” Ryan said. “We’re probably detecting in excess of 75 percent of cases. We may be missing up to a quarter of cases.”

The epicenter of the virus in recent months has been in the twin cities of Butembo and Katwa, which together have a population of nearly 1 million people. But as violence has subsided, the virus has moved to a more rural region west of those cities called Mabalako.

Ryan, who visited Mabalako recently, said it may be easier to fight the virus in a less densely populated rural area. But he said Mabalako presents its own challenges.

“The downside is, distances are longer, communities are in much more rural settings, cases are harder to find,” he said.