Lassa fever, also termed Lassa hemorrhagic fever, is a viral hemorrhagic fever caused by Lassa virus. The disease is classified under ICD-10 code A96.2 and ICD-11 code 1D61. It is endemic to West Africa and represents one of the viral hemorrhagic fevers of concern in that region.
Disease Profile
Lassa
拉沙热
Lassa fever is a viral hemorrhagic illness caused by Lassa virus, endemic to West Africa. While many infections remain asymptomatic, symptomatic cases present with fever and systemic symptoms that can progress to hemorrhage and death in approximately 1% of cases. A distinctive complication is hearing loss, affecting about one-quarter of survivors. The disease represents a significant public health concern in endemic regions, with transmission occurring through both zoonotic and human-to-human routes.
Clinical presentation of Lassa fever is highly variable, with many infected individuals remaining asymptomatic. When symptoms develop, they typically include fever, weakness, headaches, vomiting, and muscle pains. Less commonly, bleeding from the mouth or gastrointestinal tract may occur. The case fatality rate is approximately 1% among all infected persons, and death frequently occurs within two weeks of symptom onset. Among survivors, approximately 25% experience hearing loss, though hearing improves within three months in about half of these cases.
Lassa fever is endemic to West Africa, where it poses a recurring public health challenge. The disease's geographic distribution is linked to the habitat range of the multimammate rat, the natural reservoir. Outbreaks occur regularly in endemic areas, with varying magnitude depending on environmental and social factors. Surveillance burden is significant due to the disease's nonspecific early presentation and the need for specialized diagnostic capacity.
Source-backed detail is not yet available.
Source-backed detail is not yet available.
Source-backed detail is not yet available.
Effective surveillance for Lassa fever requires awareness of the disease's presence in endemic areas and consideration of the diagnosis in patients with compatible symptoms, particularly fever with systemic features. The nonspecific nature of early symptoms necessitates maintaining a high index of clinical suspicion in at-risk populations. Case investigation should include detailed exposure history to identify potential sources and transmission pathways.
- A96.2
- 1D61
Figure 1 | Full historical trajectories across all reporting countries.
Figure 2 | Year-over-year monthly comparison for seasonality and structural shifts.
Dataset Archive
Supplementary Data | Multi-country disease dataset
Machine-readable multi-country disease dataset (JSON/CSV) with source metadata.
Source Register
Official sources and update cadences used to construct the downloadable dataset.
CN
China CDC WeeklyMONTHLYweb
China
Monthly notifiable infectious disease reports published by China CDC.
Official sourceCN
National Disease Control and Prevention AdministrationMONTHLYweb
China
Official China public health bulletin and query portal.
Official sourceCN
PubMedMONTHLYweb
China
Biomedical literature discovery feed used as supplementary context.
Official sourceJP
JP NIID Weeklyweeklyweb
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.
Official sourceUS
US CDC NNDSSweeklyapi
United States
CDC National Notifiable Diseases Surveillance System provisional data.
Official sourceSuggested presentation pattern: cite the data version and coverage window when exporting charts or tables for publication.