Abstract
Baylisascaris procyonis is a helminth parasite commonly found in North American raccoons (Procyon lotor) that is a cause of clinical neural, ocular, and visceral larva migrans in humans when infective eggs are ingested. Rapid detection of B. procyonis eggs in contaminated soil and water would assist public health analysts in evaluating risks associated with public exposure to areas of known raccoon activity. In this study, a molecular beacon probe-based real-time polymerase chain reaction (PCR) assay was developed to enable rapid and specific detection of eggs of Baylisascaris spp. The molecular beacon assay targeted the cytochrome oxidase subunit 2 (cox-2) gene of B. procyonis. To determine method sensitivity, experiments testing various egg levels (250, 25, and five eggs) were performed by seeding into 0.5-g soil samples or 0.5-mL water samples. Different soil sample types were extracted using a commercial nucleic acid extraction kit. Specificity testing using previously characterized helminth tissue specimens indicated that the assay was specific to Baylisascaris spp. Little real-time PCR inhibition was observed for most of the soil and water samples. A seed level of 250 eggs was detected for all soil types, and two seed levels (25 and five eggs) were detected for surface water samples. These results demonstrate that the reported real-time PCR assay was effective for the sensitive detection of B. procyonis in a wide range of soil types, and should be a useful tool for investigations of soil or water potentially contaminated with eggs of this parasite.
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Acknowledgments
The authors thank Brian Schumacher (USEPA/NERL) for assistance in providing soil panel specimens for this study. This publication was supported in part by funds made available through the Centers for Disease Control and Prevention, Coordinating Office for Terrorism Preparedness and Emergency Response. The use of trade names and names of commercial sources is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention or the US Department of Health and Human Services. The findings and conclusions in this presentation are those of the authors and do not necessarily represent those of the Centers for Disease Control and Prevention. Experiments performed for this study comply with the current laws of the USA.
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Gatcombe, R.R., Jothikumar, N., Dangoudoubiyam, S. et al. Evaluation of a molecular beacon real-time PCR assay for detection of Baylisascaris procyonis in different soil types and water samples. Parasitol Res 106, 499–504 (2010). https://doi.org/10.1007/s00436-009-1692-6
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DOI: https://doi.org/10.1007/s00436-009-1692-6