NOMAAN MERCHANT, Associated Press

DALLAS (AP) — Health officials are intensifying the monitoring of hospital workers who cared for the first person diagnosed with Ebola in the U.S. after one of them was infected with the virus despite wearing protective gear.

The first known Ebola transmission in the U.S. has raised questions about health officials' assurances that the disease will be contained and any American hospital should be able to treat it.

Dr. Tom Frieden, head of the Centers for Disease Control and Prevention, said Sunday there was a breach of protocol that led the worker to become infected while treating Thomas Eric Duncan. But officials are not sure what went wrong.

Duncan, who traveled from Liberia to visit family, did not get sick until he arrived in the U.S. He died Wednesday.

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