Objectives Encephalitis is a complex and challenging condition with a broad differential diagnosis including infectious and inflammatory causes, often the aetiology is unknown. Eosinophilic meningoencephalitis is rare and most commonly caused by helminthic parasites although other infections and non-infectious causes are reported.
Case A 31 year old healthy Caucasian female patient was admitted via the emergency department with suspected meningitis. She had a past history of ulcerative colitis and was on mesalazine, there was no history of exposure or risk factors to suggest an underlying cause for the meningitis. There was photophobia and neck stiffness but neurological examination was otherwise normal. Initial CT brain imaging was normal. CSF examination revealed raised protein of 0.89 and 640 mononuclear cells. Subsequent serology was normal for commonly tested pathogens. MRI showed significant meningeal involvement and changes in the left superior cerebellar peduncle. Repeat CSF examination looking for possible haematological abnormalities demonstrated raised protein, cell count of 256 (lymphocytic) with normal flow cytometry and cytology. The patient improved spontaneously and was discharged but was soon readmitted with recurrence of headache and new peripheral eosinophilia. MRI again showed significant meningeal hyperintensity. Repeat CSF analysis revealed raised protein of 1.43 and 246 cells, 25% of which were now eosinophils. Again flow cytometry and cytology were unremarkable and oligoclonal bands were present unique to CSF. CT chest showed pulmonary nodules which were thought to be reactive and further neurological and haematological investigation was unrewarding. Serology was strongly positive for angiostrongylus infection. On further questioning the patient specifically denied ingestion of slugs/snails and had no immediate history of being overseas. She was managed conservatively and has remained well on follow-up.
Discussion Our patient had angiostrongyliasis with eosinophilic meningoencephalitis. Despite no known exposure, testing of angiostrongylus should be performed for eosinophilic meningoencephalitis in Australia.