Lassa Fever Epidemiology Forecast 2026-2035

Parameter

Insight

Largest Patient Pool

France

Fastest Growing Country

France

High-Risk Population

Within the specified countries, higher-risk groups include people returning from areas where Lassa fever circulates, healthcare workers caring for suspected or confirmed cases, laboratory personnel handling potentially infectious specimens, and close contacts exposed to a patient’s blood or other bodily fluids.

Key Diagnostic Method

Reverse-transcription polymerase chain reaction (RT-PCR) is a key method for detecting Lassa virus in suspected acute infection. Depending on the laboratory and clinical context, diagnostic approaches may also include antigen detection and antibody-based assays.

Major Risk Factor

The principal risk factor in the eight-country scope is exposure associated with travel to an area where Lassa virus circulates, followed by delayed recognition of illness after return. Secondary risk arises from unprotected contact with infectious bodily fluids during healthcare or caregiving.

Major gap in the market

A central gap is the lack of comparable, publicly available 2023-2026 country-level data on suspected cases, confirmed infections, diagnostic turnaround times and outcomes across all eight countries. Because infections are rare and surveillance systems may report suspected, confirmed and imported cases differently, national prevalence comparisons are not currently supportable.

Epidemiology Segment

Key Insights

Diagnosed Prevalent Cases of the Disease

A reliable diagnosed-prevalence estimate is unavailable for the eight countries. Lassa fever is an acute infection, and isolated imported cases cannot be used to calculate the number of people living with the disease at a given time. In May 2024, France reported one confirmed case in a returning military serviceman. In October 2024, US authorities investigated a suspected case in an Iowa resident who had returned from travel; the initial public report described presumptive rather than final confirmatory testing. These reports should not be treated as equivalent confirmed-case counts.

Gender-Specific Cases of the Disease

The available reports of individual imported cases do not provide a sufficient basis for estimating the distribution of Lassa fever by sex. Pregnancy is a clinically important risk context because infection can lead to serious maternal and fetal complications, but this does not establish a higher overall prevalence among women in the specified countries.

Age-Specific Cases of the Disease

Age-related patterns of Lassa fever should be assessed through documented cases and their clinical characteristics across the eight countries. The age distribution of reported infections can help identify affected population groups and inform clinical assessment. However, imported cases alone cannot establish age-specific disease prevalence or indicate that a particular age group faces a higher risk of infection. Country-level comparisons should therefore distinguish individual case reports from representative epidemiological findings.

Ethnicity-Wise Cases of the Disease

The distribution of Lassa fever across ethnic groups should be interpreted in the context of geographic exposure and documented epidemiological evidence. Ethnicity alone does not determine infection risk, as exposure is more directly associated with contact with infected individuals, contaminated materials, or environments in endemic regions. A meaningful assessment requires reliable population-level data and appropriate consideration of travel, residence, and exposure history. These factors are essential for avoiding misleading comparisons between demographic groups.

Mortality and Survival Analysis of the Disease

Lassa fever outcomes vary according to disease severity, the timing of diagnosis, access to medical care, and the development of complications. Mortality findings from individual imported cases should be interpreted cautiously and distinguished from country-level case-fatality estimates. Early clinical recognition and supportive management, including fluid and electrolyte correction and treatment of complications, remain important aspects of care. Ribavirin has been used in treatment, although uncertainty remains regarding its efficacy and optimal dosing. The absence of a licensed vaccine and a proven specific antiviral treatment continues to present challenges for disease prevention and management.

Country

Key Insights

United States

In October 2024, the CDC announced an investigation of a suspected case in an Iowa resident who had recently returned from West Africa; the initial report described presumptive positive testing, with confirmation planned. This event is evidence of travel-associated clinical concern, not a basis for estimating national prevalence.

Germany

In Germany, effective public health surveillance and timely clinical assessment remain important for identifying and managing potential Lassa fever cases. International travel and exposure to infected individuals are key factors to consider when evaluating suspected infections. Strengthening healthcare professionals’ awareness, maintaining appropriate infection prevention and control measures, and ensuring timely reporting can support early detection and preparedness against potential imported cases.

France

France reported one confirmed imported case in May 2024 involving a serviceman returning from abroad. Public health authorities initiated epidemiological investigation and contact tracing. A single imported case establishes that travel-associated infection can occur but does not indicate sustained domestic transmission or measurable population prevalence.

Italy

In Italy, preparedness for Lassa fever relies on the timely recognition of potential cases and effective coordination between healthcare providers and public health authorities. Assessing travel history and possible exposure in individuals presenting with compatible symptoms can help guide diagnostic decisions. Appropriate clinical protocols, infection control practices, and prompt communication with relevant health authorities are important for managing suspected infections and limiting the risk of further transmission.

Spain

In Spain, maintaining readiness for travel-associated infectious diseases involves effective clinical assessment and public health coordination. Healthcare professionals should consider relevant travel patterns and potential exposure when evaluating individuals with symptoms consistent with Lassa fever. Early identification, appropriate isolation precautions, and adherence to infection prevention protocols can help reduce transmission risks and support an effective public health response to suspected cases.

United Kingdom

In March 2025, the UK Health Security Agency initiated contact tracing after being notified that a person with Lassa fever had travelled to England while unwell and subsequently returned to Nigeria, where the diagnosis was made. The event prompted a public health response but was not reported as a confirmed diagnosis made in the UK. It should not be counted as a UK laboratory-confirmed case without further evidence.

Japan

Japan’s geographic separation from Lassa fever-endemic areas makes international travel and imported infections important considerations in disease preparedness. Healthcare facilities should remain equipped to recognize unusual febrile illnesses in individuals returning from affected regions. Clinical awareness, access to confirmatory testing, and coordination with public health authorities can help distinguish Lassa fever from other infectious diseases and ensure appropriate management of suspected cases.

India

India’s international connectivity and movement of people highlight the importance of considering travel-related infections within its broader infectious disease surveillance framework. For Lassa fever, clinical evaluation should account for travel to affected regions and potential contact with infected individuals. Strengthening diagnostic readiness, improving awareness among healthcare professionals, and establishing clear reporting pathways can support timely investigation and appropriate public health action when suspected cases arise.