The World Health Organization on Sunday declared an Ebola outbreak in the Democratic Republic of Congo and Uganda a “public health emergency of international concern.”

The latest epidemic, which has been caused by the Bundibugyo virus, does not yet meet the criteria of a “pandemic emergency,” the organization said.

But with a rising number of cases, at least 80 suspected deaths and no approved vaccine, fears are mounting over how effectively the outbreak can be contained. Here’s what to know.

Ebola is a severe and often fatal disease that is spread through direct contact with the bodily fluids of an infected person, according to the Africa Centres for Disease Control and Prevention (Africa CDC).

It can also be spread through contact with contaminated materials or a person who has died from the disease.