A Texas health care worker who was in full protective gear while providing hospital care for an Ebola patient who later died has tested positive for the virus and is in stable condition, health officials said Sunday. If the preliminary diagnosis is confirmed, it would be the first known case of the disease being contracted or transmitted in the U.S. Meanwhile, a top federal health official said the health care worker's Ebola diagnosis shows there was a clear breach of safety protocol and all those who treated Thomas Eric Duncan are now considered to be potentially exposed.