The risk of Ebola escaping from the Democratic Republic of Congo is now “very high,” and the outbreak already is nearing Uganda, the World Health Organization said on Thursday.
The W.H.O. raised its official alert level because of violence by local militias, which has slowed efforts to contain the outbreak, and population movements in eastern Congo, where the latest outbreak erupted in August.
But the risk of Ebola spreading globally remains low, the agency said.
Since 2000, Uganda has had three Ebola outbreaks, with a total of about 600 cases. Although it is a poor country, its health care system is relatively well organized, and its health ministry said it would start a vaccination campaign if it detected cases there.
Inside Congo, the response to the outbreak has been hampered by fighting and by small numbers of victims leaving or refusing to go to treatment centers, spreading the virus to new areas.
Also, local politicians exploiting the fear and confusion ahead of December elections were encouraging people to distrust the national government’s efforts, Dr. Peter Salama, the W.H.O.’s head of emergency response, said at a news conference in Geneva, Reuters reported.
In the coming weeks, problems like those could “create a potential perfect storm,” Dr. Salama said.
As of Friday, there have been 155 confirmed or probable cases in the Ebola outbreak. Some 102 patients have died, and 45 cured patients have been released.
In a video statement, Congo’s health minister, Dr. Oly Ilunga Kalenga, said the outbreak was now three times the size of the one this summer in the central Equateur Province. He blamed several factors.
More people live in the affected area, and they are more mobile because they are mostly traders rather than farmers. The region has better roads and water connections, but is more dangerous because many militias operate in it.
Nearly 12,000 health workers and contacts of known victims have been vaccinated.
Although cases of Ebola continued to decline and only about 10 new ones are detected each week, the W.H.O. expressed alarm that one had turned up for the first time in Tshomia, a fishing town across Lake Albert from Uganda.
Refugees often flee across the lake; just this year, 75,000 Congolese crossed it into Uganda to escape fighting in Ituri province, of which Tshomia is a part, according to a report from the European Commission’s humanitarian aid organization.
Officials in Ituri said the case was a woman who had attended the funeral of an early Ebola victim in Beni, where the current outbreak began.
She was being followed as a case contact, but she refused to be vaccinated, slipped away in between visits from medical workers, and traveled about 75 miles north before falling ill. She visited a traditional healer and a rural clinic before ultimately dying in the Tshomia regional hospital on Sept. 20.
More than 100 people in contact with her are now being vaccinated, and the mud-walled local clinic she visited had to be decontaminated.
Although health workers have not been targeted, 21 people were killed last week in Beni. An Islamic fundamentalist militia known as the Allied Democratic Forces was blamed. The group has a history of cross-border fighting with the Ugandan army, attacks on United Nations peacekeepers and massacres of civilians.
After the killings, medical staff were told to stop working for 48 hours; their subsequent efforts were hampered by a four-day mourning period declared by local officials, the W.H.O. said.
Many rumors about Ebola are circulating and must be debunked, according to the health ministry’s Twitter feed. They include reports that prisoners with Ebola had escaped from the Beni prison, that children were being vaccinated without their parents’ consent, and that schoolgirls who had their menstrual periods were being forced into treatment centers.
Four Ebola treatment centers have now been built, and a treatment team has arrived in Tshomia.
Donald G. McNeil Jr. is a science reporter covering epidemics and diseases of the world’s poor. He joined The Times in 1976, and has reported from 60 countries.