CNN
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An eastern Iowa resident who recently traveled to West Africa died after contracting Lassa fever, state officials said Monday. The virus, which falls in the same category of viral hemorrhagic fever as Ebola, is rarely seen in the United States.

The Iowa Department of Health and Human Services announced the death Monday, but did not release the person’s name and released few details about him. Preliminary tests came back presumptive positive for the virus, and the U.S. Centers for Disease Control and Prevention is working to confirm the diagnosis.

The department said the person was middle-aged and had traveled to West Africa, where he is believed to have contracted the virus.

The current risk of transmission in the United States is “incredibly low,” according to Iowa State Medical Director Dr. Robert Kruse.

According to the University of Minnesota’s Center for Infectious Disease Research & Policy, about 100,000 to 300,000 people become infected with Lassa fever each year in West Africa, where the disease is endemic. Since 1969, there have been only eight known cases in the U.S., all of them travel-related.

It is even rarer for someone to die from Lassa fever. According to the World Health Organization, the disease has an overall mortality rate of just 1%.

In severe cases, the patient may bleed; difficulty breathing; pain in the chest, back and abdomen; and vomiting.

Someone with milder symptoms may develop a mild fever, feel tired or get a headache. Most people infected with the Lassa virus have no symptoms at all.

Lassa fever can spread between people, but not through casual contact. Normally, the virus only spreads when someone comes into contact with the bodily fluids of an infected person.

Lassa fever usually spreads through the multifarious rat in West Africa. People can become ill after touching objects contaminated with rat feces or urine, or after eating contaminated food. Some people also get sick after eating the rats themselves, according to the CDC.

Prompt treatment is considered key for Lassa fever. Ribavirin, a broad-spectrum antiviral drug that works well against RNA viruses and is also used to treat hepatitis C, is the primary treatment.

Kruse said his department is investigating and monitoring the situation in collaboration with the CDC and local public health partners. Authorities are trying to determine who may have had close contact with the patient, who was treated in isolation at the University of Iowa Health Care Medical Center.

The CDC says the patient was not sick while traveling, so the risk to other airline passengers is extremely low.