Lassa virus: Iowa man dies from rare fever after recent travel to West Africa

A middle-aged resident of Iowa who had recently travelled to West Africa has died from Lassa fever, state health officials confirmed on Monday.

"I want to assure Iowans that the risk of transmission is incredibly low in our state," said Dr Robert Kruse, the state medical director of the Iowa Department of Health and Human Services, in a news release. "We continue to investigate and monitor this situation and are implementing the necessary public health protocols."

The Centres for Disease Control and Prevention (CDC) and local public health partners are working to identify anyone "who may have been in close contact with the patient, out of an abundance of caution, for monitoring," the release added.

What is Lassa fever?

Lassa fever is a virus predominantly found across Sub-Saharan Africa, spread by West African multimammate rats, which remain the only animals known to carry the Lassa virus, according to health officials. 

The illness can manifest rapidly after infection, with an incubation period of two to 21 days, the World Health Organization (WHO) says. Since 1969, there have been only eight travel-related cases of Lassa fever in the United States; in 2015, a New Jersey man died after contracting the virus.

The CDC estimates that around 100,000 to 300,000 cases of Lassa fever occur annually in West Africa, resulting in about 5,000 deaths.

How is Lassa fever spread?

People can contract Lassa fever from direct contact with infected rats, their saliva, urine, or droppings, which may contaminate food or household items. It can also spread from person to person through contact with the body fluids of an infected individual, though it is not transmissible through casual contact, such as hugging, shaking hands, or sitting nearby.

"People with Lassa fever are not contagious until after their symptoms begin," the CDC notes.

The University of Iowa Health Care system, where the patient was treated, confirmed that the resident was cared for in its Special Pathogen Unit, a specially contained area designed for handling infectious diseases. The hospital reassured the public that it "remains a safe place to receive care."

The CDC also stated that the patient was "not sick while travelling, so the risk to fellow airline passengers is extremely low." Although person-to-person transmission has not been documented in the U.S., the CDC advises heightened isolation measures for viral haemorrhagic fevers like Lassa virus.

Lassa fever symptoms

While Lassa fever can be life-threatening, most people experience only mild symptoms, such as slight fever, tiredness, weakness, and headaches. As these general symptoms resemble other conditions, many mild cases go undiagnosed, according to health officials. 

The WHO reports that about 1 in 5 infected individuals develop a severe form of the disease, which may include bleeding, vomiting, breathing difficulties, facial swelling, and pain in the back, chest, or abdomen. The overall fatality rate for Lassa fever is roughly 1%, but it can rise to 15% or higher in those hospitalised with severe cases.

Treatment options may include an antiviral drug called ribavirin, which is most effective when administered early, alongside supportive therapies such as pain management and rehydration to help ease symptoms.