Angie-LAMP for diagnosis of human eosinophilic meningitis using dog as proxy: A LAMP assay for Angiostrongylus cantonensis DNA in cerebrospinal fluid

Background: Angiostrongylus cantonensis (rat lungworm) is recognised as the leading cause of human eosinophilic meningitis, a serious condition observed when nematode larvae migrate through the CNS. Canine Neural Angiostrongyliasis (CNA) is the analogous disease in dogs. Both humans and dogs are accidental hosts, and rapid diagnosis is warranted. A highly sensitive PCR based assay is available but often not readily accessible in many jurisdictions. An alternative DNA amplification assay that would further improve the accessibility is needed. This study aimed to assess the diagnostic utility of a newly designed LAMP assay to detect DNA of globally distributed and invasive A. cantonensis and Angiostrongylus mackerrasae, the only other neurotropic Angiostrongylus species, which is native to Australia. Methodology/Principal Findings: Cerebrospinal fluid (CSF) from dogs (2020-2022) with a presumptive diagnosis of A. cantonensis infection were received for confirmatory laboratory testing and processed for DNA isolation and ultrasensitive Angiostrongylus qPCR. A newly designed LAMP assay targeting AcanR3390 in a diagnostic laboratory setting was directly compared to the reference ultrasensitive qPCR for determination of presence of A. cantonensis DNA to aid the diagnosis of CNA. The LAMP assay (Angie-LAMP) allowed the sensitive detection of A. cantonensis DNA from archived DNA specimens (Kappa=0.81, 95%CI 0.69-0.92; n=93) and rapid single-step lysis of archived CSF samples (Kappa=0.77, 95%CI 0.59-0.94; n=52). Only A. cantonensis DNA was detected in canine CSF samples, and co-infection with A. mackerrasae using amplicon deep sequencing (ITS-2 rDNA) was not demonstrated. Both SYD.1 and AC13 haplotypes were detected using sequencing of partial cox1. Conclusions/Significance: The Angie-LAMP assay is a useful molecular tool for detecting Angiostrongylus DNA in CSF of dogs and performs comparably to laboratory Angiostrongylus qPCR. Adaptation of single-step sample lysis improved potential applicability for effective diagnosis of angiostrongyliasis in a clinical setting for dogs and by extension for humans.