Officials are investigating how a Dallas health worker who treated an Ebola patient ended up with the disease herself.

They say the worker wore full protective gear while treating Thomas Eric Duncan, a Liberian man who died Wednesday at Texas Health Presbyterian Hospital. The worker doesn't know how she became infected, and officials suspect a breach in infection control protocols.

They are looking into how the worker removed her personal protective gear, which includes a gown, two sets of gloves, a face mask and an eye shield.

They also are examining the intensive medical procedures Duncan received. Those procedures include kidney dialysis and a breathing machine.

Both involve inserting tubes into blood vessels or an airway and can raise the risk of contact with bodily fluids.