World Health Organization

The first large-scale outbreak of the C strain in decades has already killed 800 of 12,000 infected people in Nigeria and in neighboring Niger this year, according to the World Health Organization.

"We've never seen this before with meningitis C," William A. Perea, coordinator of WHO's Control of Epidemic Diseases Unit, said of the resurgence of the strain.

There is currently no licensed treatment or vaccine for Ebola, which has so far killed more than 11,000 people in West Africa since the world's biggest outbreak began in the forest region of Guinea last year.

"If proven effective, this is going to be a game-changer," said Dr. Margaret Chan, Director-General of the World Health Organization, which sponsored the study. "It will change the management of the current outbreak and future outbreaks."