Ultraviolet irradiation inactivates the waterborne infective stages of Myxobolus cerebralis: A treatment for hatchery water supplies

Ronald Hedrick, T. S. McDowell, G. D. Marty, K. Mukkatira, Dolores Baxa, K. B. Andree, Z. Bukhari, T. Clancy

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


The effects of ultraviolet (UV) irradiation on the viability of the waterborne triactinomyxon stages of Myxobolus cerebralis were evaluated by vital staining and the infectivity for juvenile rainbow trout Oncorhynchus mykiss. A dose of 1300 mWs cm-2 was required to inactivate 100% of the triactinomyxons held under a static collimated beam of UV as determined by vital staining. Juvenile rainbow trout were protected from infections with M. cerebralis when exposed to 14 000 or 1400 triactinomyxon spores per fish that had been treated with the collimating beam apparatus (1300 mWs cm-2). Among all fish receiving UV-treated triactinomyxons, none had clinical signs of whirling disease, or evidence of microscopic lesions or spores of M. cerebralis after 5 mo at water temperatures of 15°C. In contrast, 100% of the fish receiving the higher dose of untreated triactinomyxons developed clinical signs of whirling disease and both microscopic signs of infection and spores were detected in all of the high and low dose trout receiving untreated triactinomyxon exposures. Two additional trials evaluated the Cryptosporidium Inactivation Device (CID) for its ability to treat flow-through 15°C well water to which triactinomyxons were added over a 2 wk period. CID treatments of a cumulative dose exceeding 64 000 triactinomyxons per fish protected juvenile rainbow from infections with M. cerebralis. Rainbow trout controls receiving the same number of untreated triactinomyxons developed both microscopic lesions and cranial spore concentrations up to 104.6 per 1/2 head, although no signs of clinical whirling disease were observed. UV (126 mWs cm-2, collimated beam apparatus) was also effective in killing Flavobacterium psychrophilum, the agent causing salmonid bacterial coldwater disease, as demonstrated by the inability of bacterial cells to grow on artificial media following UV treatment.

Original languageEnglish (US)
Pages (from-to)53-59
Number of pages7
JournalDiseases of Aquatic Organisms
Issue number1
StatePublished - Aug 10 2000


  • Disease control
  • Flavobacterium psychrophilum
  • Ultraviolet
  • Whirling disease

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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