Diagnostic methodology is critical for accurately determining the prevalence of ichthyophonus infections in wild fish populations

Journal of Parasitology
By: , and 

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Abstract

Several different techniques have been employed to detect and identify Ichthyophonus spp. in infected fish hosts; these include macroscopic observation, microscopic examination of tissue squashes, histological evaluation, in vitro culture, and molecular techniques. Examination of the peer-reviewed literature revealed that when more than 1 diagnostic method is used, they often result in significantly different results; for example, when in vitro culture was used to identify infected trout in an experimentally exposed population, 98.7% of infected trout were detected, but when standard histology was used to confirm known infected tissues from wild salmon, it detected ~50% of low-intensity infections and ~85% of high-intensity infections. Other studies on different species reported similar differences. When we examined a possible mechanism to explain the disparity between different diagnostic techniques, we observed non-random distribution of the parasite in 3-dimensionally visualized tissue sections from infected hosts, thus providing a possible explanation for the different sensitivities of commonly used diagnostic techniques. Based on experimental evidence and a review of the peer-reviewed literature, we have concluded that in vitro culture is currently the most accurate diagnostic technique for determining infection prevalence of Ichthyophonus, particularly when the exposure history of the population is not known.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Diagnostic methodology is critical for accurately determining the prevalence of ichthyophonus infections in wild fish populations
Series title Journal of Parasitology
DOI 10.1645/GE-2589.1
Volume 97
Issue 2
Year Published 2011
Language English
Publisher American Society of Parasitologists
Contributing office(s) Western Fisheries Research Center
Description 5 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Parasitology
First page 344
Last page 348