Iowa resident dies of suspected Lassa fever: What is the rare viral disease?

(NEXSTAR) — Health officials are investigating the death of an Iowa resident believed to have contracted Lassa fever, a viral disease rarely seen in the U.S.

The resident, who has not been identified, had recently returned to the U.S. after visiting West Africa earlier this month. They were not sick while traveling, making the risk to fellow airplane passengers "extremely low," according to the Centers for Disease Control and Prevention.

The patient had been hospitalized in isolation at the University of Iowa Health Care Medical Center and testing done by the Nebraska Laboratory Response Network early Monday showed that the patient was presumptively positive for Lassa fever.

While the disease is uncommon in the U.S., should the test results be confirmed, this would mark the country's ninth known case of Lassa fever since 1969 among people returning from areas where the disease is found.

Here's what to know about the potentially deadly disease.

What is Lassa fever?

Lassa fever is a viral illness spread by the "multimammate rat" found in Sub-Saharan Africa, according to the CDC. Named after the Nigerian town where the first cases of the disease were detected in 1969, Lassa fever is known to set in quickly once someone has been infected.

About 1 in 3 people develop various levels of deafness, the CDC explains. In many cases, it is permanent. When pregnant people are infected, "there is a high risk of miscarriages."

How is Lassa fever spread?

More specifically, the fever is brought on by the Lassa virus, which is spread by the aforementioned rat. The virus is spread in the rodents' urine and droppings, the CDC explains. Humans are most likely to then get the virus by eating or breathing it in. That could mean touching contaminated objects, eating food with the virus or rodents, having exposed cuts or sores that contact with the virus, or breathing in the air around infected urine or droppings.

Humans are not contagious until the symptoms start. Even then, the CDC says the disease cannot be spread "through casual contact," like hugging. It can, however, be spread through contact with an infected person's bodily fluids.

What are the symptoms of Lassa fever?

Roughly 8 in 10 people infected with the Lassa virus develop mild symptoms, according to the CDC. Those symptoms include a slight fever, a headache, and feeling tired and weak.

More serious symptoms are also possible. Those include bleeding, troubles breathing, vomiting, swelling in the face, shock, and pain in the chest, back and abdomen.

Symptoms typically appear one to three weeks after a person is infected.

Because symptoms can vary and could signify a different disease, diagnosing the viral infection can be difficult, the CDC explains.

Can Lassa fever be treated?

The short answer is yes.

The antiviral drug ribavirin has been successful in treating patients. Ribavirin is also used to treat hepatitis C, alongside other medicines, according to the Cleveland Clinic. It can also be used to treat viral hemorrhagic fevers and severe acute respiratory syndrome (SARS).

However, the CDC notes it should be given soon after a patient becomes sick. Patients may also need supportive care like rest and hydration.

In West Africa, there are about 100,000 to 300,000 cases of Lassa fever every year, and roughly 5,000 deaths related to the infection, according to the CDC. Overall, the World Health Organization says the disease's fatality rate is 1%.

Other U.S. cases

The U.S.'s first case was reported in New York in 1969 after a patient, who had visited Nigeria, developed symptoms and was hospitalized.

More recently, a fatal case was reported in 2015 by the New Jersey Department of Health and the CDC.

One day after arriving in the U.S. from Liberia, the person developed a sore throat, fever, and tiredness, which prompted them to visit a New Jersey hospital, a report by the WHO explains. They were sent home, only to return a few days later with worsening symptoms. Roughly a week after returning home, the patient tested positive for Lassa fever and passed away.

The Associated Press contributed to this report.