Infectious Causes of Eosinophilic Meningitis in Korean Patients: A Single-Institution Retrospective Chart Review from 2004 to 2018

Eosinophilic meningitis is defined as the presence of more than 10 eosinophils per μl in the cerebrospinal fluid (CSF), or eosinophils accounting for more than 10% of CSF leukocytes in patients with acute meningitis. Parasites are the most common cause of eosinophilic meningitis worldwide, but there is limited research on patients in Korea. Patients diagnosed with eosinophilic meningitis between January 2004 and June 2018 at a tertiary hospital in Seoul, Korea were retrospectively reviewed. The etiology and clinical characteristics of each patient were identified. Of the 22 patients included in the study, 11 (50%) had parasitic causes, of whom 8 (36%) were diagnosed as neurocysticercosis and 3 (14%) as Toxocara meningitis. Four (18%) patients were diagnosed with fungal meningitis, and underlying immunodeficiency was found in 2 of these patients. The etiology of another 4 (18%) patients was suspected to be tuberculosis, which is endemic in Korea. Viral and bacterial meningitis were relatively rare causes of eosinophilic meningitis, accounting for 2 (9%) and 1 (5%) patients, respectively. One patient with neurocysticercosis and 1 patient with fungal meningitis died, and 5 (23%) had neurologic sequelae. Parasite infections, especially neurocysticercosis and toxocariasis, were the most common cause of eosinophilic meningitis in Korean patients. Fungal meningitis, while relatively rare, is often aggressive and must be considered when searching for the cause of eosinophilic meningitis.