Clinical Features and Outcomes of Neuroleptospirosis in French Guiana: Insights from a Retrospective Study (2015-2021)

BackgroundLeptospirosis is a re-emerging zoonosis in French Guiana, with broad and sometimes misleading clinical spectrum. Neurological involvement, referred to as neuroleptospirosis, lacks a consensus definition. Therefore, it is likely underrecognized, raising concerns about missed diagnosis and potentially poor outcomes. This study aimed to characterize the epidemiology, clinical features and outcomes of neuroleptospirosis. Methodology/ Principal findingsA multicenter retrospective study was conducted across all public healthcare facilities of French Guiana (2015-2021). Neuroleptospirosis was defined by the combination of (i) neurological symptoms and (ii) objective evidence of neurological involvement based on cerebrospinal fluid (CSF) analysis and/or neuroimaging. Cases were compared with leptospirosis without neurological involvement. Among 146 consecutive hospital-managed cases of leptospirosis, 18 (12%) met criteria for neuroleptospirosis (incidence 0.88 cases/100,000 inhabitants/year; 95% CI 0.52-1.39). Among them, 78% (14/18) presented a meningeal syndrome, 22% (4/18) an encephalitic syndrome, and 17% (3/18) showed paresthesia. Lumbar puncture was performed in 28/146 (19%) patients, with pleocytosis observed in 18/28 (64%) patients; median CSF leukocyte count was 42 cells/mm3 (range 13-240/mm3), with lymphocytic predominance in 8/13 (62%), a slight protein level (median 0.51 g/l, range 0.32-0.88) and no hypoglycorachia. Brain MRI revealed abnormalities in 2/8 (25%) cases of neuroleptospirosis: one cerebral infarct and one pachymeningitis. Compared with patients without neurological involvement, factors associated with a diagnosis of neuroleptospirosis were an age <30 years (p=0.004, 95% CI 1.72-18), no leukocytosis (p=0.042, 95% CI 1.04-10.39) nor thrombocytopenia (p=0.012, 95% CI 1.39-14.32) during hospitalization. Neuroleptospirosis cases had milder disease: they less often progressed to sepsis (OR 0.28; 95% CI 0.10-0.79); none required intensive care admission nor died. Discussion/ConclusionsThis study provides new insights into the clinical spectrum and outcomes of neuroleptospirosis in French Guiana. Prospective studies incorporating a consensus definition, systematic CSF analysis and microbiological testing are warranted to further characterize the pathophysiology and optimize diagnostic strategies for neuroleptospirosis. Author summaryLeptospirosis is a re-emerging infection in French Guiana, with a broad range of clinical presentations. Yet, its neurological manifestations--referred to as neuroleptospirosis -- remain likely underrecognized, lacking a consensus definition. We conducted a multicenter retrospective study to describe the epidemiological, clinical features and outcomes of neuroleptospirosis. Then, we compared cases with non-neurological leptospirosis. We used a standardized definition of neuroleptospirosis, based on neurological symptoms associated with cerebrospinal fluid analysis and/or neuroimaging. Neuroleptospirosis accounted for one tenth of leptospirosis cases. Clinical presentation was largely dominated by meningitis (three quarters of cases). Laboratory parameters showed lower rates of leukocytosis and renal involvement. CSF profiles revealed moderate lymphocytic pleocytosis, closely mimicking viral infections. Strikingly, compared with non-neurological forms, neuroleptospirosis cases exhibited fewer severity markers and uniformly favorable outcomes, with lower sepsis, no deaths nor need for intensive care admission. Factors associated with a diagnosis of neuroleptospirosis were an age lower than 30, the absence of hyperleukocytosis and thrombocytopenia during hospitalization. Neuroleptospirosis accounted for a non-negligible proportion of leptospirosis cases in French Guiana, exhibiting CSF features mimicking viral meningitis, and carrying excellent outcomes. Increasing awareness and improving recognition of this presentation is essential to reduce underdiagnosis and refine patient management in endemic settings.