Seroprevalence of Angiostrongylus cantonensis in suspected human angiostrongyliasis cases and clinical manifestations in a tertiary care hospital in Thailand: a retrospective 18-year longitudinal study

Human angiostrongyliasis, a foodborne parasitosis caused by Angiostrongylus cantonensis, is primarily characterized by eosinophilic meningitis (EOM), meningoencephalitis or myelitis. This study reports the seroprevalence of A. cantonensis among suspected cases of angiostrongyliasis and describes the clinical manifestations in patients with positive serological tests at a Thai tertiary care hospital over an 18-year period (2006–2023). Among 768 patients suspected of eosinophilic meningitis related to A. cantonensis infection, 353 (46 %) tested positive for A. cantonensis IgG antibodies. Most seropositive patients were from the northeast region of Thailand (308/353; 87.2 %). Among the seropositive patients, 13 % reported a history of consuming uncooked freshwater snails or other paratenic hosts. Headache was reported in 23.5 % of the patients, with 31.3 % (n = 26) experiencing acute severe headache. Fever and neck stiffness were present in 6.8 % and 6.5 % of the patients, respectively, while nausea and vomiting were observed in 7.9 %. In a subset of 56 seropositive patients who underwent lumbar puncture, cerebrospinal fluid (CSF) examination was clear in 49 (87.5 %), cloudy in six (10.7 %), and xanthochromic in one case (1.8 %). The highest recorded CSF opening pressure was 600 mmHg, with a median pressure of 210 mmHg. The average CSF white blood cell count was 200 cells/mm³ (range: 0–2250 cells/mm³), with eosinophils constituting an average of 35 % (range: 1–90 %). These findings may be useful for clinicians in endemic regions as supportive information for clinical diagnosis.