According to the WHO and medical professionals in the DRC, most cases had a 48-hour lag between the onset of symptoms and death. The WHO says the outbreak is ‘a significant public health threat’.

As of Monday, there have been 419 cases reported, including 53 fatalities, and officials believe the outbreak started on January 21.

There is a “exceptionally high fatality rate” in one area, where two-thirds of those who got the mystery disease are known to have died.

The first outbreak began in the town of Boloko after three kids allegedly consumed a dead bat, according to the WHO’s Africa office.

They passed away 48 hours after the onset of hemorrhagic fever symptoms, which include fever, bleeding, headache, joint pain, and other symptoms.