An outbreak of Marburg, a contagious virus similar to Ebola, has impacted Rwanda and is causing concern of international spread.

Marburg has caused small, episodic outbreaks since first being identified, most recently last year in Tanzania and Ghana. It is one of the deadliest known viruses, with no approved vaccines or specific treatments.

Gilead Sciences said on Thursday it would donate about 5,000 vials of its antiviral drug remdesivir to the Rwanda Medical Supply for emergency use in response to the Marburg virus outbreak. The drug is being supplied in conjunction with Rwanda's health ministry and the Africa Centers for Disease Control,