Lassa fever–induced sensorineural hearing loss: A neglected public health and social burden

Abstract

Although an association between Lassa fever (LF) and sudden-onset sensorineural hearing loss (SNHL) was confirmed clinically in 1990, the prevalence of LF-induced SNHL in endemic countries is still underestimated. LF, a viral hemorrhagic fever disease caused by Lassa virus (LASV), is endemic in West Africa, causing an estimated 500,000 cases and 5,000 deaths per year. Sudden-onset SNHL, one complication of LF, occurs in approximately one-third of survivors and constitutes a neglected public health and social burden. In the endemic countries, where access to hearing aids is limited, SNHL results in a decline of the quality of life for those affected. In addition, hearing loss costs Nigeria approximately 43 million dollars per year. The epidemiology of LF-induced SNHL has not been characterized well. The complication of LF induced by SNHL is also an important consideration for vaccine development and treatments. However, research into the mechanism has been hindered by the lack of autopsy samples and relevant small animal models. Recently, the first animal model that mimics the symptoms of SNHL associated with LF was developed. Preliminary data from the new animal model as well as the clinical case studies support the mechanism of immune-mediated injury that causes SNHL in LF patients. This article summarizes clinical findings of hearing loss in LF patients highlighting the association between LASV infection and SNHL as well as the potential mechanism(s) for LF-induced SNHL. Further research is necessary to identify the mechanism and the epidemiology of LF-induced SNHL.

Animal Models of Lassa Fever

“…Neurological signs such as hearing loss, encephalitis, and tremors also occur [2]. Of note, this hearing loss manifests as sudden-onset sensorineural hearing loss (SNHL) in approximately one-third of patients and is irreversible in two-thirds of those cases [10,18,19]. Infections during pregnancy have a greater risk of death as well as spontaneous abortion [20].…”

Vaccine platforms for the prevention of Lassa fever

“…Neurological complications, including sensorineural hearing loss and encephalopathy, are commonly observed in Lassa fever patients [35,36]. Deafness may occur as a result of mild or severe illness and is estimated to effect 25-30% of cases.…”

“…Deafness may occur as a result of mild or severe illness and is estimated to effect 25-30% of cases. In approximately half of these individuals, hearing loss is permanent; in the remainder, partial restoration of hearing takes place between one and three months after recovery [35,36]. The potential risk of these immune-mediated adverse neurological effects will be a key consideration for Lassa fever vaccine developers.…”

The Impact and Control of Emerging and Re-Emerging Viral Diseases in the Environment: An African Perspective

“…The infection also spreads between humans through contact with body fluids of infected persons or contaminated medical equipment (Fisher-Hoch et al 1995). The Lassa virus infects approximately 500,000 people and causes about 5000 deaths worldwide (Mateer et al 2018). In endemic regions, seropositivity for Lassa virus-specific antibodies could be as high as 55% in populations residing around forested areas harbouring large populations of reservoir rodents (Lukashevich et al 1993).…”

“…Infection in infants can result in "swollen baby syndrome" with oedema, abdominal distension, bleeding and often death (McCormick et al 1987). Neurological problems, including hearing loss and encephalopathy, have been shown to occur in patients who survive the disease (Mateer et al 2018).…”