Rwanda has said it will begin vaccine trials for the fatal Marburg virus, which has already killed at least 12 people in the country - most of them health workers. The east African country has received 700 doses of the vaccine from the Sabin Vaccine Institute, a US-based non-profit organisation.

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.