Iowa resident dies of suspected Lassa fever after travel

On Oct. 28, 2024, the United States CDC issued a statement regarding a suspected case of Lassa fever in Iowa. According to the CDC statement, the patient -- who is now deceased -- returned to the U.S. from West Africa earlier this month.

Although the condition is quite rare in the U.S., 100,000 to 300,000 cases occur in West Africa annually, making travelers more susceptible. An estimated 5,000 individuals die of Lassa fever in West Africa each year. It most commonly occurs in West Africa, including Sierra Leone, Liberia, Guinea, and Nigeria. However, other neighboring countries might also be at risk.

Lassa fever is a viral infection caused by the Lassa virus that commonly spreads through Mastomys natalensis, also called multimammate rats, native to sub-Saharan Africa. These rodents carry Lassa virus in their droppings or urine.

Infected individuals might have been exposed to the virus when touching contaminated objects, eating food with the virus, getting the virus in open cuts or sores, eating rodents or breathing in air with infected urine or droppings from the rats.

According to the CDC, many cases of this infection are mild, with 80% of individuals contracting the disease going undiagnosed because they only have mild symptoms. Patients begin to exhibit symptoms within three weeks of contracting the virus.

Mild symptoms include a slight fever, fatigue, weakness and headache. However, in some cases, patients might have more severe symptoms, including bleeding, difficulty breathing, vomiting, facial swelling, chest, back or abdominal pain, and shock.

Lassa fever can also cause hearing loss, triggering various levels of deafness in one-third of patients regardless of the severity of the symptoms. Often, this hearing loss is permanent and cannot be reversed. Furthermore, infected individuals who are pregnant have a high risk of miscarriage, with 95% of cases resulting in the death of the fetus.

The serious and sometimes permanent side effects of this condition underscore the importance of identifying and monitoring cases of Lassa fever.

Although the virus is most commonly spread from rats to humans, humans can also contract it from other humans when they come in contact with an infected individual's bodily fluids. Humans are typically only contagious when symptomatic and cannot spread the disease through casual contact; however, it is possible that the virus can spread rapidly in healthcare settings without proper personal protective equipment.

CDC officials are still in the process of confirming Lassa virus in the Iowan resident; however, initial testing conducted by the Nebraska Public Health Laboratory suspects that the virus contributed to the middle-aged individual's death. If confirmed, this would only be the ninth case of Lassa virus in the U.S. since 1969, when the disease was first documented.

"This is a difficult time for the family of this individual, and I want to express our deepest condolences," said Robert Kruse, M.D., MPH, FAAFP, state medical director of the Iowa HHS, in the department's press release. "I want to assure Iowans that the risk of transmission is incredibly low in our state. We continue to investigate and monitor this situation and are implementing the necessary public health protocols."

The CDC is also investigating how the person might have contracted the virus, as well as identifying and monitoring others who were in contact with the patient when they were symptomatic.

Veronica Salib has covered news related to the pharmaceutical and life sciences industry since 2022.