Submitted to: Global Aquaculture Advocate
Publication Type: Popular Publication
Publication Acceptance Date: 4/1/2015
Publication Date: 5/1/2015
Citation: Xu, D., Shoemaker, C.A., Lafrentz, B.R. 2015. Parasitism enhances tilapia susceptibility to Flavobacterium columnare. Global Aquaculture Advocate. May/June:32-33.
Technical Abstract: Flavobacterium columnare, a Gram-negative bacterium, is the causative agent of columnaris disease. Many commercially important freshwater fish worldwide are susceptible to columnaris disease that can result in high fish mortality. Ichthyophthirius multifiliis (Ich) is a protozoan parasite in many freshwater fishes worldwide, damages fish gills and skin, and results in high fish mortality. Bacterium F. columnare and protozoan I. multifiliis are two common pathogens of cultured tilapia. The temperature ranges of columnaris disease outbreaks overlap the optimum temperature of I. multifiliis infection at 20-25 degrees C. There is no published information available on whether parasite infection will increase the susceptibility of tilapia to F. columnare. Work in this study evaluated whether hybrid tilapia infected with Ich will increase the susceptibility of tilapia to F. columnare. The results demonstrated that the Ich-parasitized tilapia showed higher mortality when co-infected with F. columnare than non-parasitized fish. The bacterial numbers in Ich-parasitized fish were 10 fold or higher than non-parasitized fish. The results of this study are important to fish health managers and farmers because prevention of parasite infection in fish may not only reduce the direct damage caused by the parasite but may also reduce fish mortality due to bacterial co-infection.