Lassa fever, a viral haemorrhagic illness endemic in parts of Nigeria, Liberia, Sierra Leone, and neighbouring countries, kills thousands each year in West Africa, yet many infections go undiagnosed until it is too late. The disease, primarily spread by rodents, can also be transmitted through contact with infected blood or bodily fluids. Travellers returning from West Africa have occasionally carried the virus abroad, resulting in fatal cases in countries such as the United States and South Africa.
A new study in Liberia, published in Lancet Infectious Diseases, found that 11% of patients admitted with fever—who were not initially suspected to have Lassa fever—were infected. Children and adolescents aged 5 to 17 accounted for approximately 43% of confirmed cases. The research underscores how the disease often goes undetected because its early symptoms—fever, headache, fatigue, and sometimes cough or sore throat—mimic common illnesses, causing delays in clinical suspicion and early intervention.
The PREPARE (Prevalence, Pathogenesis, and Persistence) study, led by researchers at the University of North Carolina School of Medicine, tested 435 patients in two central Liberian hospitals between 2018 and 2024 using PCR diagnostics. Patients with confirmed infections were monitored during hospitalization and for up to a year afterward. Those who died generally had higher viral loads and weaker antibody responses, highlighting the importance of early detection and treatment.
Undiagnosed cases not only endanger patients but also pose risks to other patients and health workers on general wards, as missed infections can lead to unprotected exposure and expanded monitoring requirements. Outbreak investigations in Liberia and Nigeria show that even a single overlooked case can result in large numbers of exposed healthcare personnel.
The study emphasizes the need for improved understanding of Lassa fever’s clinical presentation, better diagnostics, and enhanced hospital testing capabilities. Early PCR testing in regional hospitals in Liberia successfully identified infections that might otherwise have been misdiagnosed as malaria or other febrile illnesses. Such measures, combined with the development of vaccines and therapeutics, are crucial for controlling the spread of Lassa fever and protecting both endemic and global populations.
