Researchers are beginning a highly anticipated study of two possible treatments for the Ebola outbreak in eastern Congo. The World Health Organization said Thursday the first participant has been enrolled in a trial that could take months to tell if either drug helps improve survival. The virus causing this outbreak is less common than others that cause Ebola disease and there are no specific treatments or vaccines for it. The study will test if drugs called remdesivir and MBP134, given alone or in combination, help more than today’s standard supportive care.