3.4 Detection of the parasite from intermediate and paratenic
hosts
Surveys of known definitive, intermediate, and paratenic hosts are
instrumental in the tracking and quantifying of Angiostrongylus
cantonensis prevalence in the environment, and also to develop an
accurate risk assessment. Currently, surveys have been known to employ
visual methods for detection in hosts (Xie et al., 2023), as well as
molecular methods (Gamiette et al., 2023). Molecular tools such as
PCR-based detection and analysis are accurate and have the additional
benefit of being effective with both fresh and frozen snail tissue, and
with low parasite numbers (high ct value in qPCR) (Qvarnstrom et al.,
2010). The assay developed by Qvarnstrom et al. (2010) demonstrated
specificity of detection when tested against Angiostrongylus
costaricensis and A. vasorum , both known mammalian parasites,
and was thus a commonly used protocol in many subsequent studies.
However, a relatively cheaper and more accessible qPCR assay using SYBR
green was more recently developed by Jakkul et al. (2021), which
bypasses the need for probes. Apart from PCR, loop-mediated isothermal
amplification (LAMP) assays have been developed for providing low-cost
and sensitive detection of Angiostrongylus cantonensis from
invasive P. canaliculata hosts, which is an effective strategy
for large scale prevalence detection (Chen et al., 2011). However, the
specificity of this protocol against other species ofAngiostrongylus remains to be tested.
Rapid and accurate methods of identifying Angiostrongylus
cantonensis larvae within mollusk hosts as well as patient samples have
gained a substantial amount of interest as the number of outbreaks of
eosinophilic meningitis continues to rise (Rollins et al., 2021).
Furthermore, newly developed environmental DNA (eDNA) based methods may
be applied to detect many infectious diseases from environmental samples
(eg: standing water from paddy fields) which could also be applied forAngiostrongylus cantonensis detection and quantification (Bass et
al., 2023).