LIVINGSTON - A New Jersey hospital says it twice treated a patient who died this week of an infectious disease that is rarely seen in the United States.

Saint Barnabas Medical Center in Livingston said in a statement Wednesday that the 55-year-old man came to the emergency room on May 18 and was treated and released.

He returned three days later with a sore throat, fever and tiredness. He was later transferred to University Hospital in Newark where he died Monday after being diagnosed with Lassa fever.

Saint Barnabas said the man did not initially disclose that he had recently traveled abroad, but later said he had been in Liberia.

Lassa does not spread easily from person to person.