ARS | Publication request: Ich parasite serves as vector to transmit bacteria to fish

Submitted to: Global Aquaculture Advocate
Publication Type: Popular Publication
Publication Acceptance Date: November 10, 2012
Publication Date: November 30, 2012
Citation: Xu, D., Shoemaker, C.A., Klesius, P.H. 2012. Ich parasite serves as vector to transmit bacteria to fish. Global Aquaculture Advocate. November/December:82-83.

Technical Abstract: Protozoan Ichthyophthirius multifiliis (Ich) and bacterium Edwardsiella ictaluri are two common pathogens of cultured channel fish, which result in high mortality and decreased profits. Previous studies have indicated that parasite infection act as potential portals of entry for bacterial pathogens due to skin parasite-mediated injuries. This study determined whether Edwardsiella ictaluri was able to survive and replicate in Ichthyophthirius multifiliis (Ich) and become infectious in healthy channel catfish exposure to Ich using a fluorescent tagged Edwardsiella ictaluri. Healthy channel catfish were shown to become infected after the parasite was exposed to E. ictaluri. E. ictaluri was able to survive and replicate in Ich. We able to determine that 50-100% of Ich were infected with E. ictaluri. Greater than 60% of channel catfish were positive tested for E. ictaluri infection following exposure of Ich to E. ictaluri. This study indicated that healthy catfish infected with Ich be responsible for the cause of enteric septicemia of catfish. Understanding the potential ability of parasites to transmit bacterial disease is important to fish farmers and health managers particularly because parasites introduced via wild fish or fish from other farms could concomitantly involve the introduction and/or transmission of microbial disease agents.