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Title: Status of current Ichthyophthiriasis research

Author
item YU, XIAO-LI - GUANGXI FISH. RES. INST.
item GAN, XI - GUANGXI FISH. RES. INST.
item LIANG, WAN-WEN - GUANGXI FISH. RES. INST.
item Xu, Dehai

Submitted to: Aquaculture Miscellaneous Publications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2004
Publication Date: 3/24/2004
Citation: Yu, X., Gan, X., Liang, W., Xu, D. 2004. Status of current Ichthyophthiriasis research. Modern Fisheries Information 19: 14-17.

Interpretive Summary: Ichthyophthirius multifiliis (Ich) is a severe fish parasite that causes heavy mortality in many cultured fish. The parasite has a life cycle consisting of an infective theront, a parasitic trophont and a reproductive tomont. This study determined mechanisms of disease caused by Ich, compared prevention and treatment, and evaluated immune response and vaccination. Channel catfish immunized with live theronts or sonicated trophonts acquired protection against Ich. The immunized fish showed higher levels of anti-Ich antibodies in the skin and serum than non-immunized fish. Parasite infection and mortality did not occur in fish immunized with live theronts. Fish immunized with sonicated trophonts had a low infection and mortality compared to non-immunized fish. The results of this study show that vaccination against Ich is an alternative to chemical treatments since the surviving fish from an Ich infection develop immunity against reinfection by the parasite. Chemical treatment of the parasitic disease ichthyophthiriasis is limited in effectiveness, costly for fish producers, and causes public concerns for food and environment safety.

Technical Abstract: Ichthyophthiriasis causes high mortalities of fish and leads to heavy economic loss in aquaculture. The disease is caused by a ciliated protozoan Ichthyophthirius multifiliis Fouquet (Ich) that is a major parasitic disease of freshwater fish worldwide. This study determined mechanisms of disease caused by Ich, compared prevention and treatment, and evaluated immune response and vaccination. It is difficult to control the parasite using chemical treatment since the parasite penetrates into fish skin and gills, is costly for fish farmers, and there is concern for food and environmental safety. Channel catfish immunized with live theronts or sonicated trophonts acquired protection against Ich. The immunized fish showed higher levels of anti-Ich antibodies in the skin and serum than non-immunized fish. Parasite infection and mortality did not occur in fish immunized with live theronts. Fish immunized with sonicated trophonts had a low infection and mortality compared to non-immunized fish. The results of this study show that vaccination against Ich is an alternative to chemical treatments since the surviving fish from an Ich infection develop immunity against reinfection by the parasite.