The majority of people infected in Rwanda ’ s Marburg virus outbreak are health workers, and some illnesses have been reported in districts that border three other African nations, both of which are among a number of concerning features of the event, the World Health Organization (WHO) said yesterday in its initial risk assessment.

Rwanda has reported nine deaths from its first-ever Marburg virus outbreak and confirmed 18 patients are in isolation, according to its health ministry.

Rwanda says eight people have died so far from the Ebola-like and highly contagious Marburg virus, just days after the country declared an outbreak of the deadly hemorrhagic fever that has no authorized vaccine or treatment.