Human Neuroangiostrongyliasis Caused by Angiostrongylus cantonensis in Northern Vietnam: a Clinical-Epidemiological Case Series of Eosinophilic Response and Disease Manifestations.

PURPOSE: Angiostrongylus cantonensis is a major cause of eosinophilic meningitis in Southeast Asia, but clinical data from northern Vietnam remain limited. We describe the clinical spectrum, eosinophilic response and outcomes of patients treated at a national tertiary referral centre.

METHODS

We retrospectively reviewed 30 consecutive patients admitted to Bach Mai Hospital, Hanoi, between January 2018 and December 2021 who met a composite case definition of probable neuroangiostrongyliasis: clinical meningitis, peripheral and/or cerebrospinal-fluid (CSF) eosinophilia, and a reactive serum ELISA for A. cantonensis-specific antibody, with alternative causes excluded. Molecular confirmation by CSF polymerase chain reaction (PCR) was not available at the centre during the study period and no case met a definite (larva- or PCR-based) standard. Data included demographics, exposure history recorded in routine admission notes, clinical and imaging findings, and peripheral and CSF parameters at admission and across serial lumbar punctures, with paired admission-discharge values and a 6-month relapse window.

RESULTS

Mean age was 39.2 ± 17.1 years; 16 (53.3%) were men; 17 (56.7%) came from Nghe An or Thanh Hoa. Headache (30/30), neck stiffness (25/30, 83.3%) and focal neurological deficits (11/30, 36.7%) predominated. Peripheral eosinophilia (> 8%) occurred in 19/30 (63.3%); six (20.0%) had no CSF eosinophils at presentation. CSF hypoglycorrhachia (< 2.2 mmol/L) was uncommon (5/30, 16.7%); low CSF chloride (< 120 mmol/L) was present in 13/30 (43.3%). CSF cellularity, eosinophilia and protein fell progressively across serial punctures. All patients received albendazole and methylprednisolone; 26/30 (86.7%) recovered fully, 3 (10.0%) relapsed, and none died.

CONCLUSIONS

In 6 of 30 patients (20.0%; 95% CI 9.5-37.3), no CSF eosinophils were recorded on the routine differential at presentation; this should not exclude the diagnosis. The proportion is conditioned on a case definition that admits patients on peripheral eosinophilia with a reactive serology, and on the sensitivity of a routine clinical differential; both are properties of a retrospective case series and are set out in the Limitations. All patients received combined albendazole and methylprednisolone and no serious adverse event was attributed to either drug, but in the absence of a comparator group no inference can be drawn about the independent contribution of either agent. Exposure histories were abstracted retrospectively and cannot identify a transmission route. Cases were referred predominantly from the north-central provinces, indicating where prospective surveillance and molecular diagnostic capacity should be directed.