Rwandan health authorities will begin a vaccine study against the Marburg hemorrhagic fever as the East African country tries to stop the spread of an outbreak that has killed 12 people.

Rwanda, which received 700 doses of a vaccine under trial from the U.S.-based Sabin Vaccine Institute, will offer it to health workers and emergency responders as well as individuals who have been in contact with confirmed cases. There is no authorized vaccine or treatment for Marburg.

The Rwandan government said there were 46 confirmed cases, with 29 of them in isolation.

Marburg has a fatality rate as high as 88 per cent.

Marburg symptoms include high fever, severe headaches and malaise within seven days of infection and later severe nausea, vomiting and diarrhea.

It is transmitted to humans by fruit bats and then spreads through contact with the bodily fluids of those infected. 

Neighbouring Uganda has suffered several outbreaks in the past.

Rwandan Health Minister Sabin Nsanzimana said the vaccinations started on Sunday. 

"We believe that with vaccines, we have a powerful tool to stop the spread of this virus," Nsanzimana said at a news conference in the capital, Kigali, on Sunday.