Lassa Fever: US Traveler Death Under Investigation | CDC News
The Centers for Disease Control and Prevention (CDC) and the Iowa Department of Health are investigating a suspected case of Lassa fever that resulted in the death of an Iowa resident who recently returned from West Africa. Officials emphasize the risk to the general public remains extremely low, as the patient did not exhibit symptoms although traveling.
The case, diagnosed earlier this month, is being treated with the utmost seriousness. The patient was hospitalized in isolation at the University of Iowa Health Care Medical Center and initial laboratory testing by the Nebraska Laboratory Response Network indicated a presumptive positive result for Lassa fever. Confirmatory testing is currently underway.
Understanding Lassa Fever
Lassa fever is a viral illness endemic to parts of West Africa. It’s spread by the multimammate rat, Mastomys natalensis, and humans become infected through contact with the rat’s urine or feces. While less common, person-to-person transmission can occur through direct contact with an infected person’s blood, body fluids, mucous membranes, or sexual contact. The CDC explains that the virus is not spread through casual contact, and individuals are not considered infectious until they begin to show symptoms.
The World Health Organization (WHO) notes that approximately 80% of Lassa fever infections are mild or asymptomatic. However, in about one in five cases, the illness can progress to a severe form affecting multiple organs, including the liver, spleen, and kidneys. A particularly concerning complication is hearing loss, which can occur in both mild and severe cases and is often permanent.
A Rare Occurrence in the United States
Lassa fever is uncommon in the United States. According to the CDC, this suspected case would represent the ninth instance of Lassa fever diagnosed in travelers returning to the U.S. Since 1969. The scale of the disease in West Africa is significantly larger, with an estimated 100,000 to 300,000 cases and around 5,000 deaths occurring annually.
Public Health Response and Contact Tracing
The CDC is actively collaborating with Iowa state and local public health officials to determine how the patient contracted the virus. Preliminary information suggests potential contact with rodents during their time in West Africa. The CDC and other federal agencies have offered assistance to Iowa in managing the situation.
A key aspect of the response is identifying and monitoring individuals who may have had close contact with the patient after the onset of symptoms. These contacts will be monitored for up to 21 days, the typical incubation period for Lassa fever. The CDC emphasizes that the patient was not ill during travel, minimizing the risk to fellow passengers.
What We Realize About Transmission and Risk
The primary reservoir for Lassa virus is the Mastomys rat, which is widespread throughout Sub-Saharan Africa. The virus is shed in the urine and feces of these rodents. Human infection typically occurs through inhalation of aerosolized particles of these excretions or through direct contact. The WHO highlights that preventing rodent infestation in homes and food storage areas is crucial for reducing transmission risk.
While person-to-person transmission is possible, it requires direct contact with infected bodily fluids. This is why healthcare workers are at increased risk in settings where Lassa fever is prevalent, and strict infection control measures are essential.
Looking Ahead: Continued Surveillance and Investigation
The CDC is continuing to investigate the circumstances surrounding this case to better understand the potential exposure pathways and refine public health recommendations. This includes detailed analysis of the patient’s travel history and activities in West Africa. Further updates will be provided as more information becomes available. Individuals concerned about potential exposure should consult with a healthcare professional and stay informed through official public health channels.