WASHINGTON, Shawwal 10, 1435, Aug 6, 2014, SPA -- A top U.S. health official will testify at a congressional hearing on Thursday to assess the threat from the Ebola virus ravaging Africa, Reuters reported. Tom Frieden, director of the Centers for Disease Control and Prevention, was the first witness listed for a House of Representatives subcommittee hearing on "Combating the Ebola Threat." Ariel Pablos-Mendez of the global health bureau at the U.S. Agency for International Development and Bisa Williams of the State Department's African affairs bureau were also scheduled to testify, according to the Subcommittee on Africa, Global Health, Global Human Rights, and International Organizations. Two Americans, a doctor and a missionary, were being treated in isolated units at Emory University Hospital in Atlanta after having contracted the disease in Liberia. Missionary Nancy Writebol, 59, and Dr. Kent Brantly, 33, an Ebola-infected American doctor, are believed to be the first Ebola patients treated in the United States. Representatives from Samaritan's Purse and Christian missionary group SIM USA, which ran the joint team in Monrovia where the Americans worked, were also due to appear before the panel. The death toll from the world's worst Ebola outbreak has risen to 932 after 45 patients died between Aug. 2 and Aug. 4, with Liberia, Sierra Leone and Guinea the hardest hit. -- SPA 21:22 LOCAL TIME 18:22 GMT www.spa.gov.sa/w