Perspective

Every dry season, the pattern repeats
Each dry season in Nigeria brings a familiar and ominous public health threat: Lassa fever. Despite more than five decades of awareness, the country remains trapped in a cycle of seasonal outbreaks, delayed detection, underreporting, and preventable mortality [1]. Lassa fever, caused by the Lassa virus, an arenavirus, primarily spreads through contact with excreta from infected Mastomys natalensis rats that thrive in human dwellings [1-2]. The disease is endemic to West Africa, with an estimated 300,000 infections and 5,000 deaths annually, and Nigeria bears the greatest burden [3-4]. In 2023 alone, over 8,000 suspected cases and more than 1,000 confirmed infections were reported in Nigeria, with an average case fatality rate of 17.9% nationally, though some states recorded higher figures [5]. Healthcare workers remain disproportionately affected, largely due to delayed diagnosis and poor access to infection prevention and control (IPC) resources [6-7]. Compounding the issue are environmental and behavioral risk factors, such as bush burning, rodent infestation, and poor food storage, which promote seasonal transmission peaks between November and April [8].

The surveillance gap and the vaccine void
Unlike diseases such as polio or rabies, Lassa fever lacks a defined global eradication timeline. Its zoonotic reservoir makes elimination biologically improbable using current public health tools. However, this biological complexity should not justify policy inertia. Nigeria has made modest progress, most notably, the activation of annual Emergency Operations Centres (EOCs) by the Nigeria Centre for Disease Control and Prevention (NCDC) to coordinate preparedness and response during outbreak seasons [5]. However, these efforts remain largely reactive and seasonal, not part of a sustained, year-round strategic framework.

Meanwhile, international momentum is growing – Lassa fever is recognized by the World Health Organization (WHO) as a priority pathogen under its R&D Blueprint for Action to Prevent Epidemics [9]. In response, the Coalition for Epidemic Preparedness Innovations (CEPI) is supporting several vaccine candidates, including INO-4500 (Inovio) and IAVI’s rVSV-LASV vector, both currently in Phase I and II clinical trials in West Africa [10]. Complementing these efforts, the ENABLE Lassa Research programme, launched in 2019, conducted a multi-country cohort study across Benin, Guinea, Liberia, Nigeria, and Sierra Leone, enrolling over 23,000 participants to estimate Lassa virus exposure and incidence. The study reported a mean seroprevalence of ~30%, ranging from 2% in Benin to 48% in Liberia. Its follow-on phase, ENABLE 1.5, focuses on high-risk populations in Nigeria, Liberia, and Sierra Leone, expanding surveillance to young children and assessing post-infection outcomes such as sensorineural hearing loss [11]. Despite these advances, no licensed vaccine exists, and timelines for regulatory approval and deployment remain uncertain.

Repositioning the national response
There is limited public awareness of Lassa fever risk factors, uneven diagnostic capacity across states, and insufficient rodent control infrastructure [5, 7,12]. Control efforts remain fragmented, with weak integration between human health, veterinary, and environmental sectors, despite growing support for the One Health approach [13].

The challenge today is less a lack of technical knowledge and more the absence of sustained, coordinated investment across sectors. While annual outbreak responses are necessary, they cannot replace year-round preparedness and structural reform. Nigeria requires a comprehensive, multisectoral Lassa fever control strategy that articulates concrete milestones: expanding laboratory capacity with regional diagnostics and mobile platforms; establishing strategic stockpiles of antivirals—since no licensed product exists and early ribavirin treatment remains inconsistent across facilities [14]; improving housing, sanitation, and food-storage infrastructure to reduce rodent-human contact; and scaling community-based surveillance and engagement to identify early cases and shift the paradigm from reactive to preventive control.

Lassa fever remains both neglected and normalized—an unfortunate combination that perpetuates cyclical outbreaks and fragmented responses. To achieve meaningful progress, Nigeria must transition from reactive outbreak control to a sustained, integrated national strategy guided by the following priorities:

1. Surveillance and early detection: Strengthen integrated case-based surveillance through community-level reporting, real-time digital notification systems, and sentinel site expansion across endemic states. Incorporating rodent population surveillance within a One Healthframework will enable early warning of increased transmission risk and improve outbreak forecasting.
2. Laboratory capacity and diagnostic capability: Expand and decentralize diagnostic facilities beyond national reference laboratories to regional hospitals and academic centers. Investment in mobile PCR platforms, regional biobanking, and trained laboratory personnel will improve turnaround time and enhance situational awareness during peak transmission periods [6].
3. Health system preparedness and readiness: Institutionalize Lassa fever preparedness in Nigeria’s national emergency health plans. This includes strategic stockpiling of antivirals such as ribavirin, adequate supplies of personal protective equipment (PPE), and well-trained rapid response teams stationed in hotspot regions. Consistent access to early treatment remains crucial, as ribavirin remains the only widely available therapeutic option, albeit with variable distribution and efficacy [14].
4. Community engagement and risk reduction: Work collaboratively with traditional leaders, faith-based organizations, and community-based groups to strengthen culturally sensitive public health messaging. Campaigns should emphasize behavioral change—discouraging bush rat consumption, improving household sanitation and food storage, and addressing stigma toward survivors—to promote sustainable risk reduction.
5. Coordination, governance, and long-term investment: Establish an inter-ministerial coordination mechanism linking the Ministries of Health, Agriculture, and Environment to promote a unified One Health agenda. Long-term success requires dedicated national funding for rodent control, research, and vaccine preparedness, supported by public–private partnerships and donor collaboration.

Together, these priorities offer a practical roadmap for transitioning Nigeria’s Lassa fever response from episodic containment to sustained prevention, ensuring resilience against future zoonotic threats.

Community and ethical considerations
Effective Lassa fever control must go beyond biomedical measures to address social and ethical factors. In some Nigerian communities, bush rat consumption and burial rites raise transmission risks. Stigma faced by survivors often deters others from seeking care, leading to self-medication and delayed detection. Nigeria’s health system must provide equitable access to protection, clear risk communication, and survivor support. Tackling cultural practices and social determinants through community-led, context-specific strategies is essential for lasting and effective disease control.

A call to action
This commentary calls for a fundamental shift in how Lassa fever is prioritised in Nigeria. The disease should no longer be treated as a seasonal anomaly but as a persistent threat requiring a comprehensive national strategy and stronger international partnerships. Government agencies, research institutions, and global health donors must move beyond emergency response and toward structural change. If we continue to treat Lassa fever as routine, we risk normalising preventable suffering and avoidable deaths. The time to act is between outbreaks, not during them.