JOHANNESBURG (AP) — The deadly Ebola outbreak in eastern Congo has surpassed 2,000 cases and is picking up speed.

The number of confirmed cases reached the milestone three times as quickly as it took to reach 1,000. The outbreak declared in August has killed more than 1,300 people in a volatile region where rebel attacks and community resistance have hurt containment efforts.

World Health Organization spokesman Tarik Jasarevic told reporters in Geneva on Tuesday that the 2,000 figure is a "sad and frustrating milestone. The insecurity is holding us back."

Each attack keeps health workers from the crucial work of vaccinating people and tracking thousands of contacts of victims.

Aid groups including the International Rescue Committee say a "complete reset" is needed in the response to one of the world's most dangerous diseases.