KINSHASA, Congo -- Congo's health ministry says the countdown toward the end of its latest Ebola outbreak has begun, as all people who were in contact with the last confirmed case have passed the 21-day incubation period with no sign of the virus.

The ministry announced the milestone Thursday. The outbreak's end can be declared when two incubation periods, or 42 days, pass without any new confirmed cases.

There have been 38 confirmed Ebola cases, including 14 deaths, since the outbreak was declared in early May. Congo has had nine outbreaks of the virus, which was first discovered there in 1976.

The health ministry says rapid international and national mobilization, including a vaccination campaign, helped contain the outbreak that spread to several health zones, including a city of more than 1.2 million.