Acanthamoeba myelopathy mimicking tropical spastic paraparesis in immunocompetent hosts: a case series.

BACKGROUND: Acanthamoeba spp. typically causes granulomatous amoebic encephalitis in immunocompromised hosts. OBJECTIVE: [1] To describe an unusual presentation of Acanthamoeba infection manifesting as non-compressive myelopathy in apparently immunocompetent patients.  METHODS: Case series of four patients presenting with progressive spastic quadriparesis at a hospital in Kerala, India. Neuroimaging, cerebrospinal fluid (CSF) analysis, and amoeba-specific PCR were performed. Patients underwent extensive evaluation to exclude common causes of non-compressive myelopathy. RESULTS: All four patients were apparently immunocompetent. Neuroimaging revealed spinal cord lesions without encephalitis in two cases. Amoeba-specific PCR of CSF confirmed Acanthamoeba spp. in all patients. Free-Living Amoeba-associated Parainfectious Neuroinflammation Syndrome (FLA-PINS) was diagnosed. Patients showed significant clinical and CSF improvement following anti-acanthamoeba therapy at 2-5 months of follow-up. CONCLUSIONS: Acanthamoeba infection should be considered as a differential diagnosis for non-compressive myelopathy, particularly in endemic regions. Systematic screening can prevent misdiagnosis of incurable neurodegenerative diseases and enable appropriate treatment.