Updated — Oct. 12, 11:15 a.m. ET:
A health care worker who provided care to the Ebola patient treated at the Texas Health Presbyterian Hospital has tested positive for the disease, the Texas Department Of State Health Services has confirmed in a statement.
The health care worker came down with a fever on Friday night, and was moved into isolation. The person was then tested for Ebola, and on late Saturday, it came back positive.
"We knew a second case could be a reality, and we've been preparing for this possibility," said Dr. David Lakey, who is the commissioner of the Texas Department of State Health Services. "We are broadening our team in Dallas and working with extreme diligence to prevent further spread."
On Sunday, health officials said that the Ebola diagnoses indicted a breach in safety protocol among health care workers, the Associated Press reports.
The director of the National Institute of Allergy and Infectious Diseases, Dr. Anthony Fauci, said there must "have been an inadvertent, innocent breach of protocol of taking care of a patient within the personal protective equipment."
The CDC will now be investigating how hospitals are treating Ebola, from before a healthcare worker enters a patient's room, to caring for the patient, through when the patient leaves the hospital. Removing protective gear incorrectly can lead to contamination and put a healthcare worker at risk for contracting the disease.
Dr. Tom Frieden, the head of the Centers for Disease Control and Prevention, said that all other healthcare workers who came in contact with Duncan may now be at risk.
"We'll be determining how many of those potentially have had contact that would have resulted in a breakdown in protocol and possible contamination," Frieden said.
"It is possible that in the coming days we will see additional cases of Ebola," Frieden said during a press conference Sunday morning, adding that the infected health care worker was not on the original list of 48 people who could have come in contact with Duncan.
The mayor of Dallas, Mike Rawlings, said action had been taken to "decontaminate" several areas the patient had been in contact with.
He said a pet found at the address is being cared for, but had not shown any signs of the disease.
According to CNN: "The World Health Organization estimates more than 8,300 have contracted Ebola during the current outbreak. Of those, more than 4,000 people have died."
The Texas health authority had said it was monitoring the situation two days ago.
Here is the entire statement released by the Texas Department Of State Health Services:
A health care worker at Texas Health Presbyterian Hospital who provided care for the Ebola patient hospitalized there has tested positive for Ebola in a preliminary test at the state public health laboratory in Austin. Confirmatory testing will be conducted by the Centers for Disease Control and Prevention in Atlanta.
The health care worker reported a low grade fever Friday night and was isolated and referred for testing. The preliminary test result was received late Saturday.
"We knew a second case could be a reality, and we've been preparing for this possibility," said Dr. David Lakey, commissioner of the Texas Department of State Health Services. "We are broadening our team in Dallas and working with extreme diligence to prevent further spread."
Health officials have interviewed the patient and are identifying any contacts or potential exposures. People who had contact with the health care worker after symptoms emerged will be monitored based on the nature of their interactions and the potential they were exposed to the virus.
Ebola is spread through direct contact with bodily fluids of a sick person or exposure to contaminated objects such as needles. People are not contagious before symptoms such as fever develop.
This is a developing story.