A West African traveler died in New Jersey of a rare disease resembling Ebola that alarmed federal health officials.

The Centers for Disease Control and Prevention (CDC) confirmed late Monday that the man had died from a disease called Lassa fever, which is extremely rare in the United States but more common in parts of West Africa where he had traveled, reported The Hill.

The man admitted himself to a hospital on May 18 with a sore throat, fever and fatigue. He indicated travel to West Africa and was sent home the same day. He returned three days later in worse condition and died shortly thereafter.

"In rare cases it can be transmitted from person to person through direct contact with a sick person's blood or bodily fluids, through mucous membrane, or through sexual contact," the CDC said according to The Washington Post. "The virus is not transmitted through casual contact, and patients are not believed to be infectious before the onset of symptoms."

Lassa fever is typically less deadly than Ebola, but CDC together with New Jersey health officials are looking for any potential contacts including health workers, family members and people who shared his plane from Liberia to Morocco to JFK International Airport on May 17. Those considered at risk will be monitored for 21 days.

Lassa fever has never been spread from person-to-person in the United States, and there have only been six documented cases in the last 40 years. 

This case echoes the tale of Thomas Eric Duncan, a Liberian man who died of Ebola after being discharged and readmitted to a Dallas hospital.