A man diagnosed with Lassa fever after returning from a trip to Liberia has died, reports USA Today. The patient, whose name has not been released, got back to the states on May 17. He flew into John F. Kennedy International Airport and did not have a fever at that time. He went to a New Jersey hospital on the 18th with a fever, sore throat, and tiredness. But, he was sent home; hospital staff say the patient did not mention having traveled in West Africa. After his symptoms got worse, the patient went back to the hospital on the 21st and was transferred to a specialized treatment facility. He did not test positive for Ebola, but did test positive for Lassa fever, another viral hemorrhagic fever. According to a release from the Centers for Disease Control and Prevention, the patient died Monday night. Lassa fever is much less likely to spread between people — and less likely to be fatal — than Ebola. This is only the sixth known case of Lassa fever in the States since 1969, but there may be up to 300,000 cases per year in West Africa. The CDC is working with health officials to put together a list of people the patient may have had contact with. The organization has deemed the current risk to others extremely low.