Top federal health officials said Sunday that the Ebola diagnosis in a health care worker who treated Thomas Eric Duncan at a Texas hospital clearly indicates a breach in safety protocol.

Dr. Tom Frieden, head of the Centers for Disease Control and Prevention, said the worker had treated Duncan on multiple occasions after the Liberian man, who died Wednesday, was diagnosed in late September.

Frieden said the worker was doing self-monitoring. “Immediately when they developed symptoms, they isolated themselves, they were promptly isolated at the hospital so that any further spread from that individual was stopped,” he said.

As a result of this new infection, Frieden said all health care workers who treated Duncan were now considered to be potentially exposed.

“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.

The identity of the health care worker was not disclosed.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said there “certainly had to have been an inadvertent, innocent breach of protocol of taking care of a patient within the personal protective equipment.”

Frieden said the CDC will begin a full investigation of procedures, from before someone enters a patient’s room, to caring for a patient, through the time that person leaves the room and removes protective gear. Removing it incorrectly can lead to contamination.

The CDC also will look at “the interventions that were tried desperately to keep the index patient alive,” including dialysis and intubation, which can spread infectious material.

The virus that causes Ebola is not airborne and can only be spread through direct contact with bodily fluids — blood, sweat, vomit, feces, urine, saliva or semen — of an infected person who is showing symptoms.

In Spain, a nursing assistant diagnosed with the virus after caring for an Ebola patient recalled touching her gloved hand to her face while removing equipment and health authorities there are looking at that as a possible cause of infection.

“We know from many years of experience that it’s possible to care for patients with Ebola safely without risk to health care workers,” Frieden said. “But we also know it’s hard. Even a single breach can result in contamination.”

Frieden was interviewed on CBS’ “Face the Nation” and Fauci was on ABC’s “This Week.”

(AP)