The deadly Ebola virus has been contracted by someone inside the United States for the first time . A nurse who had worn protective gear during her `` extensive contact '' at a Dallas hospital with an Ebola patient who died tested positive during a preliminary blood test , officials said Sunday . The woman had on a gown , gloves , mask and a shield during her multiple visits with Thomas Eric Duncan , but there was a breach in protocol , health officials said . The patient is a nurse at Texas Health Presbyterian Hospital in Dallas , an official who is familiar with the case told CNN . The Centers for Disease Control and Prevention in Atlanta conducted testing on the blood sample , and confirmed the results Sunday , marking the first known transmission of Ebola in the United States and the second diagnosis in the country . She was involved in Duncan 's care after he was placed in isolation -- his second trip to the hospital after coming to the United States from Liberia -- said Dr. Tom Frieden , the director of the CDC . The nurse is in stable condition , Texas Health Resources chief clinical officer Dan Varga said . Duncan , the first person to be diagnosed with Ebola in the United States , died Wednesday . What 's a hospital supposed to do if an Ebola patient shows up ? The nurse had `` extensive contact '' on `` multiple occasions '' with Duncan , Frieden said . `` At some point , there was a breach in protocol , and that breach in protocol resulted in this infection , '' he said at a news conference Sunday . `` The ( Ebola treatment ) protocols work . ... But we know that even a single lapse or breach can result in infection . '' Also , Varga said that someone who is a `` close contact '' of the nurse has been `` proactively '' placed in isolation . The hazardous materials unit of the Dallas Fire Department has cleaned up and decontaminated the public areas of the health worker 's apartment complex , Mayor Mike Rawlings said . Police are keeping people out of the area and are talking to residents nearby . `` We have knocked on every door on that block , '' the mayor said . Hazardous materials units have also cleaned out the nurse 's car and will work on her apartment Sunday . `` This development is understandably disturbing news for the patient , the patient 's family and colleagues and the greater Dallas community , '' the CDC said in a statement , announcing the nurse 's test results . It sought to play down a wider risk . `` The CDC and the Texas Department of State Health Services remain confident that wider spread in the community can be prevented with proper public health measures , including ongoing contact tracing , health monitoring among those known to have been in contact with the index patient , and immediate isolations if symptoms develop , '' the CDC said . Complete coverage on the Ebola outbreak . Case was anticipated . `` We knew a second case could be a reality , and we 've been preparing for this possibility , '' Dr. David Lakey , commissioner of the Texas Department of State Health Services , said in a statement Sunday morning . `` We are broadening our team in Dallas and working with extreme diligence to prevent further spread . '' The nurse reported a low-grade fever Friday night and was isolated , the health department said . The preliminary test result came in late Saturday . President Barack Obama received two briefings Sunday on the second Dallas Ebola case , including one from Health and Human Services Secretary Sylvia Burwell . According to a White House statement , the President wants federal authorities to immediately take further measures to ensure health care professionals are able to follow protocols for treating Ebola patients . ' A sign the system is working ' The news that a health care worker might have the disease is not completely unexpected , an infectious disease specialist told CNN 's `` New Day . '' `` I think we 've always expected that there may be another individual who will come down with the Ebola from the transmission of this one particular person , and we always felt that it was going to likely be one of his close contacts or one of the health care workers , because that 's the way this virus works , '' Dr. Frank Esper said . For Ebola caregivers , enormous fear , risk and bravery . Esper said Texas officials have been keeping a close eye on people who had contact with Duncan . `` I will tell you that the fact that we identified this individual so quickly is actually to me a sign that the system is working , '' he added . Globally , the disease has wrought catastrophic consequences . The World Health Organization estimates more than 8,300 people have contracted Ebola during this year 's outbreak . Of those , more than 4,000 have died . Ebola not very contagious . Ebola is actually difficult to catch . People are at risk if they come into very close contact with the blood , saliva , sweat , feces , semen , vomit or soiled clothing of an Ebola patient , or if they travel to affected areas in West Africa and come into contact with someone who has Ebola . Those stricken with Ebola suffer ghastly symptoms , including vomiting , diarrhea , muscle pain , fever and internal bleeding . Three countries -- Sierra Leone , Guinea and Liberia -- have been hardest hit . And many of those who care for the ill have also come down with the disease . The World Health Organization estimates at least 416 health care workers have contracted Ebola , and at least 233 have died . In Liberia , health care workers are threatening to strike if their work conditions do n't improve . The first infection outside of Africa happened in a nurse 's aide in Spain , Teresa Romero Ramos . She became sick after she helped treat an Ebola-stricken Spanish missionary . Her case has prompted questions from fellow medical professionals about whether they are properly equipped to safely treat Ebola patients . Spanish Ebola patient 's condition worsens , doctor says . Another search begins . For weeks , health officials have been monitoring those who had contact with Duncan before he was hospitalized and isolated . Duncan left Liberia on September 19 and arrived in Dallas on September 20 . Four days later , he began feeling ill ; the following night , he went to Texas Health Presbyterian Hospital . But despite telling a hospital worker that he had arrived from Liberia , Duncan was sent home with antibiotics . He returned a few days later and tested positive for Ebola . And now , the search begins for all the contacts whom the nurse came in contact with . `` We need a whole new crew of people to do contact tracing , '' said Elizabeth Cohen , CNN senior medical correspondent . Because Ebola 's incubation period can last up to 21 days , the health nurse 's contacts will have to be monitored for three weeks . The Texas health department said officials have interviewed the patient and are identifying any contacts or potential exposures . `` This is not an easy thing , '' Cohen said . `` Keeping track of large numbers of people , taking their temperature twice a day , making sure they do n't ... leave town , all of that is a lot of work . ''
A ` ` close contact '' of the nurse is being monitored , says CDC . The nurse helped care for an Ebola patient multiple times , the director says . He said there was a breach in protocol and his office is closed . Nurse was wearing protective gear when she helped care for patient Eric Duncan .