The silent toll of Lassa fever is often hidden in plain sight

Health · Published 20 October 2026 Swipe more like this →

In short: For most people, Lassa fever is a mild, almost unnoticeable illness. But for the 20% who develop severe symptoms, it can be devastating. Beyond the immediate risk of death, this West African viral disease leaves behind lasting physical scars that persist long after the fever breaks.

First documented in Nigeria in 1969, Lassa fever is a zoonotic viral illness primarily spread by the multimammate rat (Mastomys). These rodents are ubiquitous across Sub-Saharan Africa, particularly in West African countries like Nigeria, Liberia, and Sierra Leone. They do not fall ill from the virus but shed it through their urine and droppings, often contaminating food supplies or household items where humans live.

The clinical presentation is notoriously variable, making diagnosis difficult. While 80% of infected individuals experience only mild symptoms—such as slight fever, fatigue, and headache—about 1 in 5 infections progress to severe disease. In these cases, the virus can damage blood vessels, leading to uncontrolled bleeding, organ inflammation (specifically the liver, spleen, and kidneys), and even sepsis or acute kidney injury. The overall case fatality rate is approximately 1%, but this jumps to 15% or higher for patients hospitalized with severe symptoms.

One of the most striking long-term complications is hearing loss, which affects about 1 out of 3 cases regardless of whether the initial infection was mild or severe. In many instances, this deafness is permanent. Furthermore, the virus poses a grave risk to pregnant women; if infected, there is a high likelihood that over 75% (with some sources citing up to 95%) of fetuses will not survive.

Prevention centers on rodent control and hygiene, as there is currently no vaccine. While the antiviral drug ribavirin can be effective when administered early, treatment primarily focuses on supportive care like hydration and symptom management. In healthcare settings, the virus can spread via contaminated equipment or body fluids, necessitating strict personal protective equipment (PPE) to prevent transmission between patients.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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