The world's second-largest Ebola outbreak hit another milestone December 11, as the Democratic Republic of the Congo (DRC) recorded two new cases, raising outbreak totals to 500, including 289 deaths.

Healthcare workers have been attacked, vaccination campaigns halted, and experts from the US Centers for Disease Control and Prevention (CDC) were recalled from an outbreak zone due to security fears. This is all despite the DRC hosting the UN’s largest peacekeeping force.

As an Ebola outbreak in a conflict-plagued region of the Democratic Republic of the Congo continues to spread after four months, there’s a glimmer of hope: An experimental Ebola vaccine appears to be helping the communities it reaches.

Efforts to trace contacts of people with Ebola in the Democratic Republic of the Congo have been hampered by mistrust in conflict-ridden outbreak zone.

Attacks by armed groups happen on a daily basis across Congo’s North Kivu province, where the Ebola virus has been spreading since August, infecting almost 500 people and killing more than 270.

Lab tests confirmed Ebola virus infections in five more people in the Democratic Republic of the Congo (DRC). The new cases lift the outbreak total to 458, which includes 410 confirmed and 48 probable cases. Health officials are still investigating 75 suspected cases.

The 16 cases reflected in the health ministry's daily updates for Dec 1, 2, and 3 and were from eight different locations: Beni, Katwa, Vuhovi, Kalunguta, Mutwanga, Komanda, Butembo, and Masereka.

Should the outbreak spread more widely in cities, the scale of the outbreak could tax the available supplies of an experimental vaccine being used to help contain spread, said Peter Salama, who heads the World Health Organization’s (WHO) emergencies program.

After nearly five months and now 426 cases, the Ebola outbreak in North Kivu and Ituri provinces of the Democratic Republic of the Congo (DRC) has become the world's second largest outbreak of the disease ever recorded.

Since September, the incidence of Ebola has more than doubled, according to World Health Organization (WHO) situation reports. The majority of people with recently identified Ebola were not on existing lists of contacts of people with previously identified cases — which indicates a high degree of unrecognized transmission in the community.