![]() ![]() Environmental DNA could enable species-level detection and monitoring in aquatic parasitology with important benefits to human health, animal welfare, freshwater fisheries, coastal aquaculture, conservation, and ecosystem health 12. As such, parasite genomic (gDNA) and nucleic (nDNA) can be captured with eDNA samples 12, extracted, and screened for target species using standard molecular genetic techniques like quantitative real-time polymerase chain reaction (qPCR) 11, 13, 14. In the case of microscopic parasites, life stages like eggs, spores, cysts, larvae, juveniles and adults can be present in the water column, in sediment, or in extracellular DNA disassociated from host organisms 12. ![]() Considering the limitation of gross visual inspection under current biosecurity protocols it is important to explore new and complimentary methods to increase biosecurity rigor and the possible integration of molecular genetic techniques.Įnvironmental DNA (eDNA) refers to the DNA that is naturally shed by organisms, such as through epidermal sloughing, metabolic waste excretions or post-mortem decay, into their local environment 11. Despite current biosecurity protocols 9, recent surveys of ornamental fish species imported to Australia have shown that a high diversity of parasites were not detected during inspection at border control, highlighting the need for more detection sensitivity 10. Australia for example, has stringent mandatory pre-export quarantine requirements, biosecurity protocols at border control, and post arrival mandatory quarantine requirements following strict biosecurity import risk assessments of ornamental fish imports 3, 8. To minimize pathogen translocation through the ornamental fish trade, governments can establish quarantine measures based on scientific risk analyses that consider the origin and history of fish stocks, parasite life cycles, host susceptibility to infection, risk of transmission to native species, and the reliability of detection methods 3, 7. Parasites and their infected hosts have been co-introduced to non-native environments with detrimental effects on biodiversity, ecosystems, industries, and dependent local communities 6. ![]() The ornamental fish trade is a known route of exotic pathogen translocations globally 1, 2, 3, 4, 5. Lastly, the proposed predictive framework has a broad utility for minimizing false positive and false negative eDNA detections of aquatic organisms. This study suggests that screening for parasite eDNA within ornamental fish consignments should be tested during pre-export quarantine periods to avoid false positive detections at border control. eDNA in non-target fish consignments demonstrates the possibility of source water contamination, limiting the applicability of eDNA screening methods at border control. Positive detections for Dactylogyrus spp. Both target and non-target consignments were positive for Dactylogyrus spp. A four-step predictive framework was used to predict putative positive and putative negative detections from quantitative PCR assays. infections) imported from Southeast Asia to Australia for the presence of eDNA from five Dactylogyrus species (Monogenea: Dactylogyridae). infections) and seven non-target fish consignments (non-cyprinids, not susceptible to Dactylogyrus spp. We examined water samples from 11 target consignments (cyprinids susceptible to Dactylogyrus spp. Detection of pathogens and parasites in the live ornamental fish trade using environmental DNA (eDNA) techniques has the potential to improve current biosecurity practices. Effective border control relies on stringent biosecurity protocols to detect and prevent introductions of exotic pests and diseases. ![]()
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