Monitoring Ceratomyxa shasta infection during a hatchery rearing cycle: comparison of molecular, serological and histological methods.

TitleMonitoring Ceratomyxa shasta infection during a hatchery rearing cycle: comparison of molecular, serological and histological methods.
Publication TypeJournal Article
Year of Publication2004
AuthorsBartholomew JL, Ray E, Torell B, Whipple MJ, Heidel JR
JournalDiseases of aquatic organisms
Volume62
Issue1-2
Pagination85-92
Date Published2004 Nov 23
ISSN0177-5103
KeywordsAnimals, Aquaculture, Body Constitution, Epithelium, Eukaryota, Fish Diseases, Fluorescent Antibody Technique, Indirect, Histological Techniques, Oncorhynchus, Ozone, Polymerase Chain Reaction, Prevalence, Protozoan Infections, Animal, Rivers, Washington
Abstract

The prevalence of Ceratomyxa shasta infection in production stocks of steelhead Oncorhynchus mykiss and cutthroat trout O. clarki was monitored using a parasite-specific polymerase chain reaction (PCR) assay. For all 4 stocks of fish followed through their 1 yr rearing cycle, C. shasta infection was detected despite their genetic resistance to the disease and the treatment of the incoming water with ozone. Infection was confirmed using serological methods and standard histological procedures, except when prevalence was low (<10%). This suggests that at the lowest infection levels PCR is more sensitive than other methodologies, and can be used as an early indicator of infection. Results of the PCR assay continued to correlate with histological and serological detection as the numbers of parasites and the lesion severity increased over the rearing cycle. For both steelhead and cutthroat trout, early infections were characterized by large numbers of parasites on the epithelial surface, but with little associated inflammation. At release as yearlings, the infection prevalence in all stocks was greater than 90 % and the inflammatory response in many fish was extensive, with tissue necrosis and mucosal damage. Although C. shasta infections no longer result in high mortality at this facility, results of this study indicate that the parasite remains a contributor to low condition indices in these fish, despite their genetic resistance and ozone disinfection of the water supply.

Alternate JournalDis. Aquat. Org.