A New Jersey man has died after being diagnosed with what is known as Lassa fever, an infectious disease from West Africa that he appeared to have contracted after coming back to New York City’s JFK International Airport from Liberia — one of the countries ravaged by Ebola since last year.

The man had returned from Liberia on May 17 but immediately grew ill, and died of multiple organ failure, according to the U.S. Centers for Disease Control and Prevention in Atlanta as reported by the Associated Press.

However, health officials are urging calm as they don’t expect this to be an outbreak on par with Ebola, which has killed thousands in Liberia as well as Sierra Leone and Guinea. Lassa does not spread through casual contact, and past cases of the disease have never involved person-to-person spread.

However, health officials with the CDC and New Jersey are taking precautions by tracking down anyone he was in contact within the past week. That includes workers at two hospitals in New Jersey and those who sat near him on his flight from Morocco to New York.

Lassa is fairly common in West Africa but is extremely rare in the United States. The last time it made its way to the U.S. was last year when someone had it in Minnesota, and the case before that was a person in Pennsylvania in 2010.

Lassa fever, in addition to not being easily spreadable, is also much less fatal than Ebola, with about 80 percent of cases being mild. However, severe cases can be deadly as it was in this case, and it can involve fever, vomiting, organ failure, and bleeding from orifices. It is fatal in about 1 percent of cases, although those who survive can sometimes lose their hearing permanently.

Lassa can be spread through bodily fluids like blood or feces, much like Ebola, and it is carried by rodents in West Africa and typically transmitted when a human comes in contact with the droppings of infected rodents.