GENEVA, Sept 25 (Reuters) - The World Health Organization said on Tuesday that an Ebola outbreak in northeastern Democratic Republic of Congo could worsen rapidly because of attacks by armed groups, community resistance and the geographic spread of the disease.
"We are now extremely concerned that several factors may be coming together over the next weeks and months to create a potential perfect storm," WHO's head of emergency response Peter Salama told a news conference in Geneva.
At least 100 people have died in the outbreak, out of 150 cases in North Kivu and Ituri provinces.
The response was at a critical juncture, and although the weekly number of new cases has fallen from about 40 to about 10 in the past few weeks and more than 11,700 people have been vaccinated, there were major obstacles ahead, Salama said.
Attacks by armed opposition groups had increased in severity and frequency, especially those attributed to the Alliance of Democratic Forces, most dramatically an attack that killed 21 in the city of Beni, where WHO's operation is based.
The city has declared a "ville morte," a period of mourning until at least Friday, obliging WHO to suspend its operations.
On Monday 80 percent of Ebola contacts -- people at risk of developing the disease and so requiring monitoring -- and three suspected cases in and around Beni could not be reached for disease monitoring.
Pockets of "reluctance, refusal and resistance" to accept Ebola vaccination were generating many of the new cases, Salama said.
"We also see a very concerning trend. That resistance, driven by quite natural fear of this terrifying disease, is starting to be exploited by local politicians, and we're very concerned in the run up to elections, projected for December, that that exploitation... will gather momentum and make it very difficult to root out the last cases of Ebola."
Some people were fleeing into the forest to escape Ebola follow-up treatment and checks, sometimes moving hundreds of kilometers, he said.
There was one such case to the south of Beni, and another to the north, close to the riverbanks of Lake Albert. Both were inaccessible for security reasons.
Neighboring Uganda was now facing an "imminent threat," and social media posts were conflating Ebola with criticism of the DRC government and the United Nations and "a range of conspiracy theories," which could put healthworkers at risk.
"We will not yet consider the need to evacuate but we are developing a range of contingency plans to see where our staff are best located," he said.
"If WHO and its partners had to leave North Kivu ... we would have grave concerns that this outbreak would not be able to be well controlled in the coming weeks or months." (Reporting by Tom Miles, Editing by Andrew Heavens, William Maclean)