Development and application of an eDNA method to detect and quantify a pathogenic parasite in aquatic ecosystems

Approaches based on organismal DNA found in the environment (eDNA) have become increasingly utilized for ecological studies and biodiversity inventories as an alternative to traditional field survey methods. Such DNA-based techniques have largely been used to establish the presence of free-living or...

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Bibliographic Details
Published in:	Ecological applications Vol. 25; no. 4; pp. 991 - 1002
Main Authors:	Huver, J. R, Koprivnikar, J, Johnson, P. T. J, Whyard, S
Format:	Journal Article
Language:	English
Published:	United States Ecological Society of America 01-06-2015 ECOLOGICAL SOCIETY OF AMERICA
Subjects:	amphibian Amphibians Amphibians - abnormalities Amphibians - parasitology Animals Cercariae disease DNA DNA - genetics DNA - isolation & purification Ecosystem Environmental conservation environmental DNA Infections organismal DNA parasite Parasite hosts Parasites PCR Polymerase chain reaction Polymerase Chain Reaction - methods Polymerase Chain Reaction - veterinary Product category rules Ribeiroia ondatrae Sensitivity and Specificity survey Trematoda - genetics Trematoda - isolation & purification Trematode Infections - parasitology Trematode Infections - veterinary Water samples North America
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Summary:	Approaches based on organismal DNA found in the environment (eDNA) have become increasingly utilized for ecological studies and biodiversity inventories as an alternative to traditional field survey methods. Such DNA-based techniques have largely been used to establish the presence of free-living organisms, but have much potential for detecting and quantifying infectious agents in the environment, which is necessary to evaluate disease risk. We developed an eDNA method to examine the distribution and abundance of the trematode Ribeiroia ondatrae , a pathogenic parasite known to cause malformations in North American amphibians. In addition to comparing this eDNA approach to classical host necropsy, we examined the detectability of R. ondatrae in water samples subject to different degradation conditions (time and temperature). Our test exhibited high specificity and sensitivity to R. ondatrae , capable of detecting as little as 14 fg (femtograms) of this parasite's DNA (1/2500th of a single infectious stage) from field water samples. Compared to our results from amphibian host necropsy, quantitative PCR was ~90% concordant with respect to R. ondatrae detection from 15 field sites and was also a significant predictor of host infection abundance. DNA was still detectable in lab samples after 21 days at 25°C, indicating that our method is robust to field conditions. By comparing the advantages and disadvantages of eDNA vs. traditional survey methods for determining pathogen presence and abundance in the field, we found that the lower cost and effort associated with eDNA approaches provide many advantages. The development of alternative tools is critical for disease ecology, as wildlife management and conservation efforts require reliable establishment and monitoring of pathogens.
Bibliography:	Corresponding Editor: M. E. Hellberg. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1051-0761 1939-5582
DOI:	10.1890/14-1530.1