Neuropsychiatric complications of clinically mild lassa fever with low viraemia: a case report from a global hotspot in Owo, Ondo State, Nigeria

Abstract

Lassa fever is traditionally classified as a viral haemorrhagic disease characterised by systemic symptoms and potential for catastrophic bleeding. While Nigeria remains the global epicentre, evolving clinical patterns suggest that neuropsychiatric manifestations are becoming increasingly prominent, particularly in Ondo, Edo and Bauchi States. These features often present in patients lacking classic haemorrhagic signs, leading to potential misdiagnosis as primary psychiatric disorders or complicated malaria. A 29-year-old female resident of Owo presented to the accident and emergency department of the Federal Medical Centre, Owo, with a 5-day history of fever, accompanied by vomiting and diarrhoea starting 3 h prior to evaluation, and new-onset focal seizure observed upon arrival. History revealed that she had identified and disposed of a Mastomys species rodent at her residence 7 days earlier. Notwithstanding high cycle threshold values (35 and 36) indicative of a low systemic viral burden, the patient manifested severe, progressive neuropsychiatric distress. This included profound emotional lability, fine tremors, and persistent, refractory insomnia that failed to respond to intravenous benzodiazepine sedation. Subsequent administration of a full course of intravenous ribavirin, coupled with targeted supportive and symptomatic management, achieved complete clinical recovery and resolution of all neurological and psychiatric deficits. This case illustrates that central nervous system morbidity may present early in clinical Lassa fever, even in the absence of an overt systemic crisis. The marked clinico-biological dissociation between low systemic viraemia and severe neuropsychiatric distress suggests direct viral neurotropism or a sequestered neuro-inflammatory response independent of systemic viral burden. Initial misdiagnosis as complicated malaria exemplifies the diagnostic traps present in endemic hotspots, where atypical presentations are increasingly documented. Neuropsychiatric symptoms may be significant in Lassa fever, even without haemorrhage or high viral loads. Clinicians should consider acute psychiatric changes, refractory insomnia, and seizures as critical clinical clues that warrant prompt evaluation. This emphasizes the urgency of integrating neuro-phenotyping and stringent environmental rodent control into revised clinical management strategies to improve patient outcomes. This is a case report not a clinical trial, hence clinical trial number is not applicable.