Unusual Larva in the CSF and Unique MRI Findings in a Case of Eosinophilic Meningitis

Eosinophilic meningitis may be caused by non-infectious and infectious agents. Angiostrongylus cantonensis is the commonest causative agent of eosinophilic meningitis. Rats are the primary hosts of this parasite. Humans get infected by ingestion of raw or inadequately cooked hosts (snails or monitor lizard) or food contaminated with the infective third-stage larvae. A 16-year-old boy was admitted to our hospital with history of fever, headache, and altered sensorium. Magnetic resonance imaging of the brain showed unique findings. Cerebrospinal fluid (CSF) examination showed eosinophilia and the CSF wet mount identified a larva. Patient history revealed ingestion of monitor lizard 2 weeks prior to onset of symptoms. Hence, a diagnosis of eosinophilic meningitis caused by A. cantonensis was made. He was treated with oral albendazole and steroids, resulting in gradual improvement. A. cantonensis as a cause of eosinophilic meningitis is a possibility in patients who present with headache and vomiting after eating raw meat (monitor lizard). To the best of our knowledge, this is a very rare case being reported from India where the larva was identified during the microscopic examination of the CSF.