Project Detail
Project: Epidemiology of Whirling Disease: An Integrated Study of the Rock Creek Drainage, Montana
Primary Investigator: Willard GranathProject Summary: This study continued a long-term project that began in 1998. The main objectives are to assess the overall epidemiology of whirling disease throughout this ecosystem including the relationship of M. cerebralis-infected T. tubifex to infection rates and severity of whirling disease in trout. The effect of water flow and habitat conditions on the transmission of the parasite were also examined and work was continued to genetically-characterize T. tubifex recovered from this drainage. Overall, the results indicated that infected T. tubifex are found throughout the drainage, but they are present in much greater numbers and are more widely dispersed in areas with degraded riparian habitat. Also, trout become infected at many locations where infected T. tubifex were not recovered, and it is possible that the fish at some of these sites were being infected by parasites originating several hundred or even thousands of meters upstream. Results also indicated that infection rates in sentinel fish have increased throughout the course of this study, with one exception, when a less susceptible test strain of rainbow trout was used for the exposures. It also appears that the range of M. cerebralis within the Rock Creek drainage is still expanding, more than 5 years after its initial detection. Heretofore no timeline concerning the spread of whirling disease, after the introduction of the parasite into a river drainage, has been established. Preliminary data do not reveal a correlation between localized streamflow and the severity of infection in sentinel fish; however, total water flow appears to affect the severity of disease as an apparent dilution effect on TAMs was observed in the upper portion of the drainage. All three T. tubifex genotypes (as determined using RAPD's) that are present in the study reaches are susceptible to infection.
Funding Period: 2002-2003
Final Report: Granath_02-03.pdf
Dataset(s) associated with this project:
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