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United States Department of Agriculture

Agricultural Research Service

Research Project: VACCINOLOGY AND IMMUNITY OF AQUATIC ANIMALS Title: Concurrent Infections (Parasitism and Bacterial Diesease) in Tilapia

Authors
item Shoemaker, Craig
item Xu, Dehai
item Klesius, Phillip
item Evans, Joyce

Submitted to: International Symposium on Talipia in Aquaculture
Publication Type: Proceedings
Publication Acceptance Date: August 1, 2008
Publication Date: October 12, 2008
Citation: Shoemaker, C.A., Xu, D., Klesius, P.H., Evans, J.J. 2008. Concurrent infections (parasitism and bacterial diesease) in tilapia. Proceedings of the 8th International Symposium on Talipia in Aquaculture. Cairo, Egypt October 12-14, 2008. Volume 2: p 1365-1375.

Interpretive Summary: Most laboratory studies to date with respect to disease in tilapia have focused on a single parasite or a single bacterial pathogen. In intensive tilapia aquaculture, the reality of a single disease agent resulting in death loss is probably small. More likely, multiple disease agents are present (i.e., parasites, bacteria and/or a combination) and responsible for disease. This paper will focus on concurrent infections or the potential for concurrent infections in tilapia aquaculture. We will highlight a recent study completed at our laboratory on parasitism with a monogenetic trematode and subsequent bacterial infection with Streptococcus iniae in Nile tilapia (Oreochromis niloticus). Concurrent infection with Gyrodactylus niloticus and S. iniae resulted in significantly higher mortality in tilapia (about 42%) as compared to immersion infection with S. iniae alone (7%) and parasitism with G. niloticus only (0%). Gyrodactylus niloticus provided a portal of entry for invasive bacteria due to damage of the fish epithelium. Interestingly, G. niloticus was also found to harbor viable S. iniae at 24 and 72 h post infection suggesting that G. niloticus may vector S. iniae from fish to fish.

Technical Abstract: Most laboratory studies to date with respect to disease in tilapia have focused on a single parasite or a single bacterial pathogen. In intensive tilapia aquaculture, the reality of a single disease agent resulting in death loss is probably small. More likely, multiple disease agents are present (i.e., parasites, bacteria and/or a combination) and responsible for disease. This paper will focus on concurrent infections or the potential for concurrent infections in tilapia aquaculture. We will highlight a recent study completed at our laboratory on parasitism with a monogenetic trematode and subsequent bacterial infection with Streptococcus iniae in Nile tilapia (Oreochromis niloticus). Concurrent infection with Gyrodactylus niloticus and S. iniae resulted in significantly higher mortality in tilapia (about 42%) as compared to immersion infection with S. iniae alone (7%) and parasitism with G. niloticus only (0%). Gyrodactylus niloticus provided a portal of entry for invasive bacteria due to damage of the fish epithelium. Interestingly, G. niloticus was also found to harbor viable S. iniae at 24 and 72 h post infection suggesting that G. niloticus may vector S. iniae from fish to fish.

Last Modified: 10/24/2014
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