Shares of Tekmira Pharmaceuticals, one of a few companies to have developed Ebola treatments advanced enough to be tested on people, soared in early August 4 trading, but later slumped after a CNN report suggested that privately held biotech company Mapp Biophamaceutical could be first to see its Ebola treatment used to treat an outbreak in Africa.

CNN said two American missionary workers who had contracted Ebola were treated with varying success by a Mapp drug.

In July, the US Federal Drug Administration had placed a hold on a clinical trial for a Tekmira drug in development, citing safety concerns. Later it said it "stands ready" to work with patients in need of treatment.

Hope that Tekmira's drug might be used in the wake of the outbreak sparked gains of more than 18% in the company's share.  

No drugs as yet have been officially approved by the FDA for human use under normal circumstances, reports say.